Journal of Engineering Geology

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Introduction
The rock block volumes are formed due to the intersection of discontinuities in the jointed rock mass. The block dimensions affected by joint spacing, joint orientation, joint sets, are taken to be the most important parameters determining the rock mass behavior, strength parameters, and deformations. In the numerical modeling using distinct element method, the creation of the discontinuities can affect the final results very much. Using 3DEC software, it is possible to create joint sets in four conditions: regular and persistent, regular and non-persistent, non-regular and persistent, irregular and non-persistent. As an important point to consider, the major effect of block dimensions on rock mass behavior, strength parameters and deformation modulus can help to decide which one is most suitable to indicate the real conditions of rock mass. As explained in the previous studies, the use of persistent joints leads to the block dimensions being considered as small ones. In this way, due to the high strength of intact rock compared to the joints, the possibility of instability increases.
Material and methods
In this research, from quantitative point of view, Geological Strength Index (GSI) is calculated, based on block dimensions as an influential parameter, to consider the most appropriate case for creating joints in the numerical method. In this regard, according to valuable studies in Bakhtiari dam structure, the characteristics of discontinuities system and GSI of rock mass are utilized to come up with real conditions. Then, the modeling is done with different conditions of joints, block volume distribution, GSI for each case, and the results are compared with quantitative ones. And then the most suitable case for creation of joints in numerical modeling is suggested by using 3 DEC software, regarding the blocks volumes, type of distribution function, and GSI value. Also, the accuracy of this finding is investigated for other structures, independently of input parameters, by making changes in spacing, and joints persistence as two effective parameters in rock blocks dimensions. Owing to the difficulty in the accurate definition of joints persistence, which is related to dimensions of the location, the numerical models for joint persistence are done in an acceptable level in order to create blocks with high conformity in terms of the dimensions. Then, the comparison is made between block dimensions from perspectives of numerical models and GSI values, to choose the best ones showing high conformity with real conditions.
Results and discussion
The comparison of the modeling results using creation of joints in different cases with quantitative results obtained according to geological strength shows that the created block volumes are not properly distributed due to the creation of joints as irregular ones in the two cases of persistent and non-persistent. In this case, the blocks volume changes from a few centimeter to cubic meter, and as the block dimensions increase, the created blocks become bigger. Thus, according to the created blocks volume and the obtained GSI range, the creation of joints is not a suitable method as an irregular one. The creation of regular and persistent joints is not an appropriate method either, as the most created blocks are small, and blocks volume distributions do not comply with quantitative distribution. But with creation of joints as regular and persistent ones, the distribution function of blocks volume in numerical method and quantitative method is log normal. Therefore, according to the created blocks dimensions and GSI range using 3DEC software, the most suitable case is the creation of joints as regular and non-persistent ones. 
Conclusion
According to the obtained results in the four cases, when the joints are considered only as regular and non-persistent ones, the blocks volume range is more compatible with real conditions and follows log normal distribution. Thus it can be concluded that the suggested method for creation of joints in the numerical modeling using 3DEC software is more suitable than others considering the rock blocks dimensions and their distributions. This method can be utilized in any structure to accurately define the persistence of joints regarding created blocks dimension.

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Introduction
When saturated sandy soils are subjected to seismic loadings, the pore water pressure gradually increases until liquefaction happens and settlement occurs during and after an earthquake. The mentioned problem is attributed to rearrangement of grains and redistribution of voids within the soils. Over the years many methods have been presented to increase liquefaction resistance. However, the main methods utilized in liquefaction mitigation are classified as densification, solidification, drainage and reinforcement techniques. Utilizing scrap tires in soils is a kind of soil reinforcement which has a wide range of application.
Waste material expulsion is one of the environmental problems each country faces. Accumulation of non-degradable polymeric materials in landfills has serious environmental consequences. Efforts to find new ways of soil reinforcement have drawn the attention of researchers towards the use of new recycled materials like scrap tires derivatives. Derivatives of scrap tires have different applications in civil engineering such as reinforcing soft soil, as a drainage layer in landfills and as filler materials.
Material and methods
In this paper a series of 1g shaking table tests were performed to investigate on the effect of tire powders-sand mixture in reducing liquefaction potential, settlements after earthquake and pore water generation. Shaking table is made of Plexiglas with inner dimensions of 200×50×70 cm. At bottom of the container a void chamber is made by using a number 200 sieve so that the saturation process could be done gradually and uniformly. A plastic plate was rigidly fixed at the center of container to separate reinforced and unreinforced samples from each other and waterproofing carefully. Therefore two models (reinforced and unreinforced) can be tested at once with the same input acceleration. An absorbing layer of foam with 2 cm thickness was employed to decrease the effect of boundary conditions in order to avoid a direct confrontation model with a rigid container. Firoozkuh No. 161 sand and tire powders were used for the mixture in reinforced side, and pure sand in unreinforced side. In this study 4 mixture ratio (TC=5%, 10%, 15% and 20%) were done. Both of unreinforced (pure sand) and reinforced (tire powders-sand mixture) models were prepared by wet tamping method, in which soil is mixed with 5% water. Each model was prepared in six layers. The required weight for each layer was considered based on the desired density (relative density is zero) and exact volume of the layer. Each portion was placed into the model container and then tamped to reach desired level. Carbon dioxide (CO₂) was allowed to pass through the specimen at a low pressure in order to replace the air that trapped in the pores of the specimen. Then water was allowed to flow upward through the bottom of the container at low pressures in order to flush out the CO₂ that cause increasing the final degree of saturation. Vibration with approximate uniform amplitude and 2 Hz frequency was applied to the container.
Results and discussion
Results indicate that acceleration within the soil tends to be increased towards the soil surface. On the other hand, after initial liquefaction (that occurred at un-reinforced models), acceleration is decreased due to the increase in excess pore water pressure. Also, it can be seen that the increase in tire powders ratio remarkably reduces the maximum excess pore-water pressure ratio. The settlement of the tire powders-reinforced models is significantly less than the unreinforced models, and with the increase of the tire powder percentage shows a very small increase of volume. The outcomes show that the value of the mean damping ratio versus the shear strain range of 0.01 is increased with the increase in tire powder content. Shear modulus is obtained from the ratio of the difference in maximum and minimum stress and strain developed in desired loop. The maximum of the shear modulus in reinforced models is more than the unreinforced models.
Conclusion
The main aim of the present paper was to investigate the influence of reinforcing a saturated sandy soil with tire powders on the soil dynamic properties and the mitigation of liquefaction potential. The following conclusions were drawn from this research.
- The increase of pore-water pressure leads to a reduction in soil shear stiffness and acceleration amplitude.
- Reinforcing sand with tire powders reduces the excess pore-water pressure ratio because of liquefaction and increases liquefaction resistance. 
- Reinforcing sand with tire powders decreases settlement caused by liquefaction.
- The damping ratio decreases at large shear strain as liquefaction occurs.
- Maximum shear modulus and mean damping ratio of reinforced soil has been increased with increasing tire powder content in the mixture../files/site1/files/123/3BahadoriFarzali.pdf

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Introduction
Many studies have shown that the lime stabilization method can increase the strength and hardness of cohesive soils. Increasing these parameters is dependent on several factors such as curing time, lime content, clay minerals, soil particle size and moisture content.
When lime is added to moisture clay soils, a number of reactions occur to improve soil properties: 1- short-term and 2- long-term reactions. The short-term reactions include cation exchange, flocculate and carbonation; whereas, the long-term reactions include pozzolanic reactions. Since adding lime changes clay particles structure, it can change shear strength parameters.
Using geogrids as reinforcement in soil mass creates a composite system in which the soil tolerates compressive stresses. The elements of the reinforcement are also responsible for tensile stresses and interaction the reinforcement elements and soil increases the strength and ductility. The mechanism of stress transfer is based on interaction between soil and reinforcement. Accordingly, one of the most important issues in the analysis and design of reinforced soil structures is determination of frictional resistance parameters in soil-geogrid interface (adhesion and friction angle) which is discussed in this paper.
Stability and performances of reinforced earth structures significantly depend on the shear behavior of interface soil-geogrid in different weather conditions. Factors such as rainfall, seepage of groundwater and seasonal changes influence on soil moisture content. Changes in moisture content or soil dry density change interface soil-geogrid resistance. Increasing moisture content reduces the shear strength of reinforced soil and sometimes leads to large deformation or failure of system.
In this study, clayey soil with low plasticity (CL), hydrated lime for soil stabilization and two types of geogrid with different aperture size for reinforcing were used. In order to improve the brittle behavior of lime stabilized soils and to increase ductility of the samples, in the present study, lime stabilization and geogrid reinforcement was investigated, simultaneously. The interface shear strength parameters of treated soil with different lime content-geogrid and reinforcement coefficient were determined by direct shear tests. In addition, to study the effect of moisture content on interface shear strength soil-geogrid, all samples were subjected to shear in optimum and higher moisture content because the long-term performance of reinforced cohesive soils exposed to seasonal variations is evaluated.
Material and methods
The selected soil for the study is clayey soil from south region of Tehran, Iran. According to Unified Soil Classification System (USCS), the soil was classified as CL (clay of low plasticity).
In this study, three series of specimens were prepared and tested as follows:

• Stabilized samples with 0, 2, 4 and 6% lime for 7 days curing time
• Reinforced samples by geogrid (with and without transverse ribs of geogrid)
• Reinforced stabilized samples with different lime contents (0, 2, 4, 6 and 8%) by geogrid (with and without transverse ribs of geogrid) for 7 days curing times

To investigate the effects of bearing resistance provided by the transverse members of the geogrid and their contribution to the overall strength for reinforced soil sample, numerous tests were conducted with the geogrid without transverse members (all the samples had the same number of longitudinal members of the geogrid).
Direct shear tests were carried out on specimens based on ASTM D5321 at constant horizontal displacement rate of 1 mm/min.
Results and discussion
The results reveal that the shear strength of the stabilized soil increased and there are maximum values in an optimum lime content which is about 4%. Increasing lime content to an optimum lime content of clay caused the maximum changes in clay minerals because of cementitious and pozzolanic reactions and increases the strength of the clayey soil. Reduction of strength by adding lime to the soil more than the optimum content may be caused by the following reasons:
1. Stopping pozzolanic reactions because of finishing reactance during reaction
2. Making difficult the release of limewater (Ca OH ₂) in the cementitious context of soil.
Until SiO₂ and AL₂O₃ are not finished, pozzolanic reactions continue and produce cementitious product, thus the shear strength increases and improves the long-term performance of the stabilized soils.
Reinforced soil samples have higher shear strength relative to samples without reinforcement subjected to the same normal stress. This increase in shear strength is mainly attributed to the interlocking of soil particles that penetrate through geogrid apertures. In addition, geogrids restrain particles´ movement and thus increase the mobilized frictional resistance at particle contact points.
Increasing in lime content to 4% (optimum lime content in this study) has significant effect on the development of adhesion and then decreases gradually with increasing of lime content from 4 to 6%, while friction angles remain constant approximately.
Adhesion and friction angles decrease with increasing moisture content.
The results show that the reinforced stabilized specimen with 4% lime has the maximum value of reinforcement efficiency. The increase in moisture content can significantly reduce the reinforcement efficiency.
It is clearly observed that the reinforcement coefficient of reinforced stabilized sample by geogrid that has smaller aperture opening size (4Í4 mm) is higher than reinforced stabilized sample by another geogrid (10Í10 mm) in optimum and higher than optimum moisture content.
Conclusion
One hundred and twenty samples in 3 specimen categories including lime treated, reinforced and reinforced treated samples were prepared for the current study for 7 days curing time in optimum content and higher than optimum content. The main results can be concluded as:
The test results indicate that the shear strength of stabilized clayey samples increases after 7 days curing time due to pozzolanic reactions.
The results show that reinforced samples have higher shear strength relative to unreinforced samples.
Adhesion and friction angles and reinforcement efficiency decrease with increasing moisture content.
The reinforcement coefficient of reinforced stabilized sample by geogrid 1 that has smaller aperture opening size is higher than by geogrid 2. In general, interaction between particles and geogrid with smaller mesh size is stronger because of matching the size of soil particles and meshes../files/site1/files/123/8Extended_Abstract.pdf
 

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Introduction
     Ground-penetrating radar (GPR) method is a pretty new, non-destructive and high-resolution geophysical method that is widely used to identify the thickness of snow and ice layers and glaciers bed, because snow and ice are transparent for electromagnetic (EM) waves. Therefore, this method has been used to determine the thickness and basement topography of Alam-kooh glacier. In this research, only the GPR acquired data using unshielded antenna with central frequency of 25 MHz along one line in Alam-kuh glacier, Kelardasht- Mazandaran, have been processed and interpreted. The GPR data acquisition has been done by using common offset method, and transmitter-receiver separation of 6 meters. The final real radargram related to one of the surveyed GPR profiles in this region has been prepared after applying various processing operations containing signal saturation correction, amplitude gain, f-k migration filtering and static (topography) correction on the raw data. After applying processing sequences on the acquired data, the EM waves reflection off the interfaces of different layers including the reflections from the glacier basement have been detected, and by assigning a suitable EM wave velocity in the ice (0.16 m/ns), the thickness of 50 m for the ice layer laid under the survey line has been estimated. Also, in present research, forward and inverse modeling of GPR data have been performed to employ for snow, ice and glaciological investigations in the AlamKooh region of Mazandaran. To achieve this goal, GPR response of synthetic model corresponding to the real radargram was simulated first, by 2-D finite-difference time domain (FDTD) method. Afterward the inversion method by solving an optimization problem was employed to validate the interpretation of real GPR data.
Methodology and Approaches
     Based on the nature, physical and geometric properties of the subsurface target in the field data, their synthetic model have been built and their two-dimensional GPR responses forward modeling using ReflexW software and finite difference algorithms improved in the frequency domain, have been obtained. Also, it has been used an effective algorithm, coded in GUI environment of MATLAB programming software and as a result, a reliable and accurate inverse modeling has been carried out. In the present study, to simulate the behavior of the propagation of EM waves in GPR method, two-dimensional finite difference method has been used. The main advantage of this method is its comparative simplicity of the concept, high accuracy and simple implementation for complex and arbitrary models as well as easily adjusting the antenna when applied. In this study, acquisition of GPR field data and synthetic data modeling have been carried out in TM mode. The radargrams of the GPR data have been demonstrated using ReflexW software after performing necessary processing sequences.
Results and Conclusions
     The obtained results reveal that moraine materials covering the surface of the area are mainly fine-grained granite. The bed-rock or basement in the area is also granite. The polarity representing ice-bed rock is clearly seen on the GPR profiles. The topography of the glacier basement has successfully been detectable using just by GPR method. The electrical resistive nature of the glacier has caused large penetration depth of GPR pulses in this research. Furthermore, the results of the research for presented profiles on the basis of forward and inverse modeling output of GPR data in comparison with real GPR radargrams in the region validated the accuracy of GPR investigations in the area. Although with a quick glance, the error obtained by the inverse modeling for real GPR data seems unexpected and unacceptable, absolutely the high rate of error depends on many factors influencing on the real earth models containing various limitations existing in all forward modeling algorithms and software packages, impossibility of making forward modeling exactly according to the real models (due to the complex nature of the ground), taking into account the homogeneity and uniform host environment and targets in the modeling process unlike the diversity, the presence of different types of noises and so on. Therefore, making a controlled geophysical test site and trying performance of inverse modeling algorithm for field GPR data in this site, as well as determining the important physical parameters such as dielectric permittivity and electrical conductivity by experimental method through sampling from different depths for complex geological environments are suggested../files/site1/files/124/1ahmadpur%DA%86%DA%A9%DB%8C%D8%AF%D9%87.pdf

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Introduction
One of the main problems in the Golestan province watersheds is the high degree of erosion and soil degradation, so that the equilibrium between the soil process and the soil erosion is unbalanced, and the erosion rate increases from west to east. Among these, the gully erosion and piping have the highest role. Gully is a canal or stream with the headcut with active erosion, sharpened slope and steep walls that results from the destruction of surface flow (usually during or after the occurrence of precipitation), dissolution movements, and small mass movements. The extent of gully in the eastern parts of Golestan province has caused the land degradation of arable land and landscape and has increased the conservation cost and etc. Because of connecting upstream areas of the basin to the downstream areas, gully has particular importance, which provides the possibility of sediment and pollutant transport, road destruction and financial losses to agricultural lands. In order to prevent and control the development of gully processes from a small scale to large one, it is a versatile utility to identify and extract the areas prone to gully erosion.
Due to the high intensity of gully erosion and its increasing growth in the Gharnaveh watershed, the Garnaveh River has an unstable status and severe eroded gully, and in some areas it has a great depth and vertical lateral walls, as well. Therefore, in this research, the watershed of Garnaveh was selected to prepare the risk areas of gully erosion.
The aim of this research is to determine Gully Erosion Hazard zoning using Frequency Ratio and Gupta & Joshi methods (Gully Nominal Risk Factor-GNRF) in the Garnaveh watershed (Golestan province). Ultimately, the accuracy of the model has been evaluated using quality sum method and Kappa coefficient.
Material and methods
The study area is located in the northern part of Iran, Golestan province. The Garnaveh watershed with an area of about 78430 hectares lies between longitudes 370360 E and 414472 E, and latitudes of 4183819 N and 4155267 N (UTM Zone 40).
At first, gully erosion inventory map with the scale of 1:75,000 (dependent variable) for the Gharnaveh watershed has been prepared using multiple field surveys and satellite images. From total gullies, 70% have been selected randomly for building gully erosion hazard zoning model and the remaining ones (30%) have been used to validate the provided model.
In this research, seven data layers including slope percent, slope aspect, plan curvature, lithology formation, land use types, distance from rivers and distance from roads have been selected as gully erosion controlling factors (covariates/ independent variables) and then they have been digitized in ArcGIS software. The amount of Gully density of each factor class has been calculated from a combination of independent and dependent variables, and the rating of classes have done based on Frequency Ratio and Gully Nominal Risk Factor equations. Finally, the Gully erosion hazard zoning map has been drawn from the summation of weighting maps in ArcGIS. In this map, the value of each pixel is calculated by summing the weights of all the factors in that pixel. The pixel values are categorized based on the natural breaks classifier into very low, low, medium, high and very high hazard zones. Then, an accuracy of zoning map has been evaluated by quality sum method and Kappa coefficient.
Results and discussion
The result of affecting factors classification of the gullies shows that loess deposits formation, rangeland, areas with low distance from road and rivers, northwest aspect, low slope amplitude and concave slopes contain the most susceptibility to gullying. The results of frequency percent comparison of gullies in hazard classes show that from all gully zones in the validation step of the GNRF and frequency ratio models %74.52 and %78.11 of zones are located in the high and very high risk classes, respectively. The result of model validation using the quality sum method and a Kappa coefficient show that the frequency ratio model is a more appropriate model for gully erosion hazard zoning (with the quality sum and a Kappa coefficient of 3 and 0.89, respectively) than the GNRF model (having the quality sum and Kappa coefficient of 1.27 and 0.74, respectively).
Conclusion
In this research, the areas susceptible to gully erosion in the Gharnaveh watershed have been mapped with the frequency ratio and GNRF (for the first time) models. For this purpose, 7 affecting factors (independent variable) and 805 gully zones (dependent variable) were provided to measure the hazard maps of gully erosion. The following results are obtained from this study.
- The geology factors were identified as the most effective factors in the occurrence of gully erosion in the Gharnaveh watershed.
- Based on the gully erosion zoning hazard map of the Gharnaveh watershed, more than 70 percent of gullies are situated in the very high and high hazard classes.
- The produced gully erosion hazard map is useful for planners and engineers to reorganize the areas susceptible to gully erosion hazard, and offers appropriate methods for hazard reduction and management, as well../files/site1/files/131/4Extended_Abstract.pdf
 

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Introduction
Ground-penetrating radar (GPR) is a high-resolution geophysical method which uses electromagnetic waves with high-frequency in order to map structures and objects buried in subsurface without any destruction of the medium. In present research, choice of optimum parameters of real data acquisition for this method has been studied. The governed behavior on the GPR fields can be simulated by solving the Maxwell’s equations and the appropriate boundary conditions that form the basis of electromagnetic theory. Among the variety of available numerical methods, the finite-difference time-domain (FDTD) method has paid more attention due to having the simple understanding of the concepts, flexibility, simulation and modeling of complex environments and the acceptability of its responses in the applied cases. The purpose of this study is to identify what reasonable information can be obtained from field data under different environmental conditions and different survey parameters.
 
Materials and methods
To achieve the goal, first forward modeling of GPR data has been carried out for several synthetic models corresponding to common targets in subsurface installations, using 2-D finite-difference time-domain method by means of GPRMAX, ReflexW and Radexplorer softwares. The main purpose of the simulations is investigation of the effect of survey parameters such as spatial sampling intervals (trace interspacing) and temporal sampling frequency on the GPR response of targets with various physical and geometrical parameters. Also to select and design the most appropriate conditions and survey parameters for real GPR data, numerous field traverses were performed in Isfahan University of Technology campus over the pre-known buried cylindrical targets containing power cable, petro-gas pipe, water pipeline and waste water pipeline with diverse host media. In this operation due to having one monostatic GPR system equipped by shielded antenna with central frequency of 250 MHz, some of the survey parameters containing central frequency, antenna separation and antenna directivity are invariant. The most important investigated survey parameters are temporal sampling frequency, spatial sampling distance (trace intervals), time window and number of stacked traces.
 
Results and discussion
Regarding carried out investigations through field data acquisition, in only one case the GPR system failed to detect any understated targets which this mode is related to choice a sampling distance of 1 cm and a sampling frequency of 504 MHz. The sampling frequency of 504 MHz is just capable to detect the surface water pipeline (due to its low burial depth). Also only in three cases the GPR system is capable to detect all subsurface targets so that the first mode of the trace interval is 2 cm and the sampling frequency is 1954 MHz, whereas in the latter two, the trace interval is 1 cm and the sampling frequencies have been selected 1563 and 1954 MHz. At the end success or failure of the targets detection was investigated on the basis of selected survey parameters and the probability of successful target detection was determined depending on the temporal and spatial sampling frequency so that the maximum probability of target detection is regarding to temporal sampling frequency of 1954 MHz and trace interval of 1 cm. Regarding GPR field data acquisition, considering the relations between the central frequency of GPR measurement systems, the depth of penetration and resolution, the diversity of materials and various components of the host media of targets and their surface overburdens a range of dierse equipments with a variety of frequencies is needed, which all of them are not generally available.
 
Conclusion
As a general conclusion of this study, in order to reduce the risk in GPR data acquisition operation, optimal survey parameters are suggested as follows:
The sampling frequency should be about 7 to 8 times the central frequency of the employed system (should not be less than this value in order to avoid aliasing and on the other hand, due to reduction in the amount of data and thus the memory needed for storage and processing), trace interspacing equal to 1 cm (in order to detect all buried targets especially targets with small size), the number of stacked traces equal to 16 (to reduce the amount of computer memory required for processing and storing data) and time window according to the computational-empirical relation (1).
                                                                                                                                                                (1)
Where W is time window, D is the maximum depth and V is the minimum velocity.
The results of this research are not restricted to the investigated case, but in practice are applicable for cases with similar host environments, especially in urban areas (which application of non-destructive methods such as GPR is necessary)../files/site1/files/131/6Extended_Abstract(1).pdf

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Introduction
Retaining walls are geotechnical structures built to resist the driving and resistant lateral pressure. In terms of serviceability life, these walls are divided into two groups including short-term structures (temporary), such as urban excavation project, and long-term (permanent) structures, such as Mechanically Stabilized Earth Walls (MSE Walls). Retaining walls are implemented by two main methods including Top-down and Bottom-up. Among the reinforcements applied in the Bottom-up walls, one can name geocells, geogrids, metal strips, and plate anchors. On the other hand, the common reinforcements applied in the Top-down walls are grouted soil nails and anchors and helical (screw) soil nails and anchors.
Plate anchors are burial mechanical reinforcements that have one or multiple bearing plates with a bar or cable to transfer the load to an area with stable soil. Among different types of plate anchor applied in onshore and offshore projects, one can name simple horizontal, inclined, and vertical plate anchors, deadman anchors, multi-plate anchors, cross-plate anchors, expanding pole key anchors, helical anchors, drag embedment anchors, vertically loaded anchors (VLAs), suction-embedded plate anchors (SEPLAs), dynamically-embedded plate anchors (DEPLAs) like Omni-max and torpedo anchors, and duckbill, manta ray and stingray anchors.
The present research reports the results from physical modeling of plate anchor retaining walls under static loading. The evaluation parameters in this work include the geometry, dimension, and reinforcement configuration of plate anchors on wall stability. PIV technique was employed to observe critical slip surface. It is worth mentioning that PIV is an image processing technique firstly used in the field of fluid mechanics to observe the flow path of gas and fluid particles. This method was used in geotechnical modeling by White et al. (2003) and few reports are already available about its application to observe wedge failure of mechanically stabilized retaining walls.
Material and methods
To carry out tests at a laboratory scale, a dimensionality reduction ratio of 1/10 was applied. Thus, all dimensions of the designed retaining wall were divided by 10. As a result, a retaining wall with a height and length of 3000 mm was reduced to a wall with 300×300 mm² dimensions. To build a retaining wall, a chamber was designed with a length, width, and depth of 1000 mm, 300 mm, and 600 mm, respectively.
The soil used in all tests was the sandy soil supplied from Sufian (in Eastern Azerbaijan, Iran). According to the Unified Soil Classification System (USCS), the soil is classified as poorly graded sand with letter symbol ‘SP’.
To create a perfect planar strain condition and prevent any friction between the footing and the lateral sides of the test box, the footing length was selected 1 mm smaller than the 300 mm width of the test chamber. Therefore, the length, width, and thickness of footing were selected as 299, 70, and 30 mm, respectively.
The length and diameter of applied tie rods were respectively 300 mm and 4 mm, which are the smaller scales of 3000 mm length and 40 mm diameter tie rod. The two sides of the tie rods were threaded to plate anchors and wall facing. Four polished square and circular anchor plates with two different areas were used. The area of small and medium circulars are respectively equivalent to the area of small and medium square plates.
Because no post-tensioning occurs in these plate anchors, the horizontal and vertical distances were both selected as 1500 mm. By applying a dimensionality reduction coefficient of 1/10, a 150 mm center-to-center distance was obtained for reinforcements in the wall. Accordingly, three applied reinforcement configurations including 5-anchor, diamond, and square configurations were used.
To construct permanent retaining wall facing, prefabricated or precast concrete blocks with a thickness of 300 mm were used. Wood (2003) conducted a dimensional analysis and introduced four types of material with different thicknesses for a 300 mm concrete facing in laboratory modeling. Accordingly, a 0.9 mm thick aluminum plate was used in the experiments performed in the present work.
Results and discussion
With an increase in dimensions of anchor plates, an increase in bearing capacity of footing and a decrease in horizontal displacement of the wall are noticed. By comparing the 24 mm footing settlement in three configurations, with changing dimension of the plates from C1 to C2 and S1 to S2 respectively, 63% increases are observed in bearing capacity of the wall.
An increase in anchor plate dimensions results in a significant decrease in wall displacement. Therefore, changing the plates from C1 to C2, S1 to S2 leads to 24% and 28% declination in wall displacement.
By changing reinforcement configuration from square to diamond, diamond to 5-anchore, and square to 5-anchor, respectively, 27%, 31%, and 67.5% increases in bearing capacity for small plates, 9.2%, 27%, and 38% for medium plates are achieved using a comparison of the final loading steps in experiments. An analogy of percentages shows that a decrease in the effect of changing the reinforcement configurations on the bearing capacity of the wall with an increase in plate anchors dimensions is reached. 
Conclusion
In the present research, a set of laboratory experiments were carried out to evaluate the stability of mechanical retaining walls reinforced with plate anchors with different geometries (square and circular), sizes (small and medium), and configurations (diamond, square, and 5-anchor). The main results of the present work can be outlined as follows:
• The maximum bearing capacity is for the 5-anchor configuration since it has one more reinforcement. After 5-anchor configuration, the diamond configuration results in a higher bearing capacity compared to the square configuration.
• Circular anchor plates compared to square anchor plates provide a higher wall stability and in the most of the experiments lead to higher bearing and lower displacement in the wall.
• Wall displacement in a diamond configuration with one less reinforcement shows a little difference with 5-anchor configuration. The maximum wall displacement occurs in a square configuration and more wall swelling is observed in the wall middle height due to inefficient anchors configuration in the wall.
./files/site1/files/132/2Extended_Abstracts.pdf

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In this research, the relationship and reaction between quantitative and qualitative Shahre Rye spring’s karstic water (Cheshme Ali) and spring’s adjacent alluvium aquifer have been considered to determine the relationship between alluvial and karstic aquifers and to study the connections between the two different groundwater environments. The results of the present research suggest geological conditions, hydrogeology and different hydraulic condition between Cheshme Ali karstic water with its surrounding alluvium’s aquifer. However the study results show the lack of a hydraulic connection between the two different groundwater environments (karst and alluvium) that are formed by north Rye fault.
Introduction
There have been many studies in the field of the present research, some of which are mentioned below.
(Tobarov, 1966). The N. Massei et al. (2002). (Robert E. 2005). (Ezatollah Raeisi 2008). (Cholami et al. 2008). (N. Goldscheider and C. Neukum 2010). (Dusan Polomcic et al. 2013).
The aim of this research is to identify the hydraulic relation between the alluvial aquifer and the karstic aquifer of the Cheshme Ali, during which the geographic, topographic and geologic situations and the changes in water discharge of Cheshme Ali and the changes in water table of the observation wells of the aquifer to the north of the spring have been reviewed simultaneously.
The results indicate a lack of relation between the alluvial aquifer and the karstic aquifer of the Cheshme Ali in Shahre Rye.
The general specification of the study area
The surface area of Shahre Rye equals to 2,293 km² and the city is limited to the north by Tehran, to the south by Qom, to the east by Varamin and Pakdasht and to the west by Islamshahr, Robat Karim and Zarandieh (Fig. 1). The Cheshme Ali is located in the eastern parts of the city and southeast of Tehran. From a geographic point of view, the Cheshme Ali spring is situated in the southern part of the Cheshme Ali hill, and after leaving the ground, the spring's water flows to the south of Shahre Rye.
Methodology
1. Topography
The topographic specifications of the Cheshme Ali and its surrounding are as follows:
The highest points of the Cheshme Ali's surroundings are the Sepaye Hills with an altitude of 2,085 m above the sea, which are located to the east of Cheshme Ali. The height of Bibi Shahbanoo hill to the southeast of Cheshme Ali is about 1,498 m. The altitude of the northern hill of Cheshme Ali, where the spring is located is about 1,077 m and the lower sloped land surrounding it have an altitude of 1,072 m above the sea. This means that the opening of the Cheshme Ali spring is located at 1,072 m above the sea.
2. Geology
From the geological point of view, the existing units around Cheshme Ali of Shahre Rye consist of Precambrian, Mesozoic and Cenozoic sediments and rocks as geological specifications of Cheshme Ali and its surroundings are shown in Fig. 2.
From the structural geology, and geological specifications two geological sections AB, CD Were prepared and presented in Figure 3.
The Figure 3 shows, Cheshme Ali spring appears from Cretaceous thick layered limestone (Tizkooh formation Kt1) and the shahre Rye fault mechanism on either side of layering. However the water flow of cheshme Ali is nearly east – westerly after spring’s openings (A) and then spring water flow direction is to the south (Fig. 4).
The hydrogeology of the spring and the wells
1. The Cheshme Ali in Shahre Rye is a karstic spring, with few hydrogeological specifications that are concluded from the result of geological and hydrogeological review and analysis of the spring’s water quality.                                                           
Therefore, the karstic Cheshme Ali spring has a varied range of discharge which is from medium (25 to 100%) to high (>100%). Moreover in the curves of the spring’s discharge and simultaneous rainfall, shown in figure 5, the peak volume of water discharge of the spring corresponds fully with the peak rainfall, underlining the influence of simultaneous rainfall on the spring.                
The study of the hydrographic makeup of the spring (curve 2) shows the difference in the period between the upward curve (seven and a half months) and the downward curve (four and a half months) underlining the lower permeability of the spring’s intake area versus the grounds conducting spring water to the openings.
2. The hydrogeology of the surrounding wells:
For the purpose of studying the fluctuation of water tables of the observation wells around the spring and in its adjacent alluvial aquifer, the isobaths maps of groundwater level and groundwater table of the spring’s surrounding areas were drawn ( Fig.6). The level of groundwater table to the north of spring is 5.9 m and 6.6 m to the south of it, while the spring water is at ground level. In order to have a better understanding of the potentials of groundwater table in Shahre Rye’s Cheshme Ali and its surrounding environments from south to north, the potential profile is provided in figure 7 using the potential figures of witness wells and the Cheshme Ali spring. In the potential profile, the groundwater level of the Cheshme Ali is higher than the groundwater potential level of the witness wells, which seems to suggest the recharge of the plain by the spring.
The review of the groundwater quality in wells and the Cheshme Ali spring
The groundwater quality characters of the Cheshme Ali and the wells to the north and south of the spring are presented in table 2,that shows three differences and similarities in the results of the chemical analysis of water from Cheshme Ali and from wells located to the north and the south of the spring. The difference between the chemical composition of water from the spring and the chemical composition of the well located to the north is considerably more than the difference between the chemical compositions of the spring and the well located to the south.
Summary and conclusion
Based on the geological studies of this research, the Cheshme Ali spring in Shahre Rye appears from the Karstic Tizkooh formation (Fig. 2) and the geological structure shows a northerly direction for the slopes of the layers in Tizkooh formation, and an east-westerly direction for the appearance of the spring water (Fig. 3 and Fig. 9). The spring’s flow is disseminated and the spring is of Karstic - fault type (table 1). The discharge of Cheshme Ali corresponds entirely to rainfall and is influenced a lot by it (Fig. 5). The condition of groundwater table of the well and the spring (Fig. 6, A) and the water level potential of the spring and its surrounding wells underlines the existence of two different hydraulic environments (Fig. 6, B). Moreover, from the aspect of potential groundwater column, there is a large difference between the groundwater table potential of the spring and the potentials of the two wells to the north and south of the spring (Fig. 7and8). From a qualitative aspect, the quality of spring water differs greatly from the quality of water from the wells located to the north and south (table 2).
The results of this research are as follows:
1. The study of geologic, structural geology and the geological section shows the water in the Cheshme Ali of Shahre Rye is originating from the Karstic formation of Tizkooh that layers sloping are to the north, the spring water appears from the site of the Rye fault and then flows to the west.
2. The studies have proven that Cheshme Ali to be a Karstic – fault spring with disseminated flow, whose discharge is influenced by rainfall and condition of groundwater level and the table which underlines the alluvial aquifer shows lack of relation between two alluvial and karstic aquifers.
3. The water quality analyses show a great difference between the specifications of the spring water and its surrounding wells groundwater.
4- The north Rye fault mechanism are formed two different groundwater environment ( Karstic and alluvium) and however different groundwater conditions between north and south of alluvium.

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Introduction
The dispersivity phenomenon occurs due to the dissolution of some of the ions in clay soils or against the shear stress of normal water flow in cohesion-less soils. Water surface flows in low slopes cause surface erosion of dispersive soils. Dispersivity in the soil starts from a point and gradually expands; the starting point can be the holes from the activity of the animals, the existing cracks or the growth path of the roots of the plants. There is a lot of field evidence to recognize the dispersivity of the loess soils. In field investigations, soil dispersivity can be detected according to the following parameters: geological origin of the loess soil, mineralogical composition, gradation, drainage pattern, slaking of agglomerates, specific morphology, high permeability, geographical area (length and width relative to origin), soil color, relationship between slope and soil erosion, precipitation, erosion of column cracks, heeling, mud flowing runoff and the presence of salt crystals in loess soils. In terms of sedimentological characteristics and engineering geological properties, Golestan loesses have been dispersed in three areas 1, 2 and 3, which are consistent with the loesses of clay, silt, and sand types, respectively.
Material and methods
Loess soils in three regions of east and northeast of Golestan province were sampled. Sampling was conducted in two forms of wax-coated agglomerates and metallic cylindrical tubes. Depth of sampling follows the foundation of the buildings located on the Mehr Housing site and the Cheshme Lee village, varying from 0.5 to 2 meters. On the path of the Beqqeje Bala village, sampling was carried out from the path trench. After transferring to the laboratory, samples were subjected to gradation testing, Atterberg limits test to determine the unit weight of the volume and density.
The pinhole test was done on samples with the unit weight of normal volume (g_n) and maximum volume (g_dmax) and its rate of dispersion was determined. The research background, field evidence and the results of laboratory experiments indicate the dispersion of soil sampling areas. The results show that soil compaction reduces the severity of dispersion and decreases the flow rate, so that the flow rate has decreased in the Maravehtapeh sample by 38%, in the Cheshmeli sample by 13% and in the Beqqeje Bala sample by 43%. Compaction cannot eliminate the dispersion of soil. Adding nanoclay decreases the severity of soil dispersion and eliminates its dispersion properties in most cases.
In order to evaluate the effect of nanoclay on severity and to decrease the dispersion property of soil with ratios of 0.5, 1, 2, 3, 4 and 5 wt%, of Montmorillonite Nanoclay was added.
The nanoclay used in the present research was selected from the Sigma-Aldrich America Company called montmorillonite nanoclay and was purchased from its domestic representative, i.e. Iranian Nanomaterials Pioneers Company. The product has a density of 300 to 370 kilograms per cubic meter and a particle size of between 1 and 2 nm. The specific surface area of the nanoparticle is about 250 square meters per gram. Its color in normal light and in 1 to 2% moisture is yellow to yellowish buff.
Results and discussion
The rate of dispersion of samples with nanoclay was measured in Pinhole Test Apparatus. Also, the method of mixing nanoclay with dispersive soil shows different behaviors in severity of dispersion and its reduction. Given that the specific surface of nanoclay is high and this property can include the whole surface of soil grains as a sticky coating and increase soil cohesion, the mixing method is practically one of the most important steps in examining the effect of nanoclay on soil stabilization. At ratios of 0.5, 1, 2, 3, 4 and 5 wt% of nanoclay, nanoclay was mixed with soils of sampling regions by four methods:
In the method A, they were completely mixed with the preparation of a homogeneous mud from soil and nanoclay via an electric mixer.
In the method B, mixing of loess soil with nanoclay was performed in optimum water content.
In the method C, mixing of loess soil with nanoclay was conducted in the form of dough by hand mixer. In the method D, mixing of loess soil with nanoclay was carried out in the form of vibration dry by grading sieve shaker.
After mixing with nanoclay in the desired method (four methods A, B, C, D), the samples were first stored in sealed plastic containers for 24 hours. Then, the samples containing nanoclay were reconstructed in cylindrical mold of the pinhole device with the unit weight of maximum dry volume and moisture of two percent higher than the optimum moisture content and a hole was created in the middle of it. The samples remained in this position for 24 hours, and then the test was performed. Testing was carried out on each sample according to the standard D4647-93, and flow rate reading was done over a period of two minutes to 18 minutes.
Conclusion
The conclusion of this study shows that the three loess samples taken have a dispersivity potential and the flow rate is low in the unit weight of maximum volume, but the dispersivity potential does not eliminate. Adding nanoclay with any weight ratio reduces the flow rate and eliminates the soil dispersivity potential.
The results of this survey showed that 1% nanoclay weight ratio is technically and economically the most appropriate mixing ratio. With this weight ratio, the method of preparing homogeneous mud with an electric mixer (method A) produces the lowest flow rate, so that the flow rate from 1.3 ml per second in pure soil to 0.3 ml per second in the soil containing nanoclay is reduced by 50 mm. Therefore, it can be said that this method is more suitable, but it is not operationally efficient and the method B is more appropriate. In the method B, the flow rate reaches from 1.3 to 0.55 ml per second.

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Introduction
The main objective of this contribution is to focus on the portion of the comminution process which deals with the prediction of the energy consumption due to the comminution portion of the milling processes.
The comminution energy in mineral processing and cement industry is usually determined by empirical Bond Work Index (BWI), regardless of the mechanical properties of a rock. The BWI is a measure of ore resistance against grinding and is determined by using the Bond grindability test. Determining the BWI value is quite complicated and time consuming. Its value constitutes ore characteristic and is used for industrial commination plants designing and optimization. The BWI is defined as the calculated specific energy (kW h/t) applied in reducing material of infinite particle size to 80% passing 100 µm. The higher the value for BWI, the more energy is required to grind a material in a ball mill. The energy consumed in the process of comminution depends on both the mechanism of comminution and the mechanical properties of the materials being ground. It is interesting to study the effect of the essential ones of these properties on the energy efficiency of grinding process.
Material and methods
Several attempts have been made to obtain and optimize the comminution energy. An efficient Response Surface Method, (RSM)-based method for the BWI approximate value determination, which is based on physico-mechanical tests, is presented in this paper.
BWI and some physico-mechanical tests on 8 typical rock samples and its correlation are studied; it would be beneficial to examine this relation based on physical concept. The database including Uniaxial Compressive Strength (UCS), Abrasion (AT), Hardness (HT) and Modulus of Elasticity (ME) are assembled by collecting data from Haffez experiments.
Results and discussion
The determination of the BWI from RSM- based multivariate model is almost matched with measured Bond’s work index. As a result of analysis the best equation obtained from RSM-based model is formulized in Equation 1:
                                      (1)
Standard statistical evaluation criteria are used to evaluate the performances of predictive models.
Conclusion
The performance of the estimator models can be controlled by R², VAF, RMSE, MAPE, VARE and MEDAE. The RSM- based model with higher VAF as well as lower RMSE, MAPE, VARE, MEDAE shows better performance in comparison to the Haffez single-variable models. AT and ME have the greatest effect on the value of BWI; and also HT has the least impact../files/site1/files/134/6.pdf

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Because of the diversity in petrography, peridotites have variable physical and mechanical properties. For this reason, knowledge of resistance properties and their deformation will help with the prediction of engineering behavior of these rocks. Due to the large spread of igneous rocks, especially peridotite, in Zagros, northeastern and central Iran, special attention has been paid to their petrographic, physical and mechanical characteristics. The construction of the structure within or on the peridotites and the choice for the purpose of the stone borrow depends on the recognition of its engineering geology characteristics. In this paper, in addition to the field and laboratory study, the geological characteristics of peridotite engineering has been investigated.                                    
Material and methods                    
In order to study the geological characteristics of the peridotites of Harsin region, 15 suitable blocks were selected and transferred to the laboratory. Accordingly, from collected rock samples, 150 cylindrical cores of diameter 54 mm were prepared and physical and mechanical tests were performed according to (ISRM, 2007) and (ASTM, 2001) guidelines. In this research, after sampling of the study area and preparing the core for the lithological characteristics of the samples by providing thin sections of them with polarizing microscopy was studied.
Results and discussion
By considering the results of laboratory tests and analysis from Harsin peridotites in Kermanshah province, we can acclaim that with increasing the percentage of minerals in olivine and pyroxene in rock, the strength was decreased and the levels weaknesses, which is due to the weak structure of the mineral-olivine and pyroxene. According to the physical properties test and Anon classification, the porosity percentage in porosity percentage is low and as a result the amount of water absorption index is low. Based on the Gamble classification, all peridotites are very resistant to durability and based on the Franklin and Chandra classification, all samples are extremely resistant. The results of this study showed that the single axial compressive strength, elasticity modulus, point load index and tensile strength were decreased with an increase in humidity content of peridotite samples. This is due to the fact that with the increase of humidity pore pressure of water increases. According to the Anon classification, the peridotites are very high in terms of the length of the longitudinal passage through the rock. The highest compliance between the Brazilian Tensile strength test (BTS) and Schmidt hammer (SHV) was achieved in the dry condition and the determination coefficient (R²) equals to 0.95 was obtained. Also there is an acceptable relation between the Brazilian Tensile Strength Test (BTS) and the dry volume unit weight (γ_d) with the determination coefficient (R²) of 0.93. In addition, there is an admissible relationship between durability test and single-axial compressive strength, with a coefficient determination (R²) of 0.94. Regarding the obtained regressions in this study, the physical and mechanical properties show good agreement and most of the equations have an acceptable coefficient determination.

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Introduction
Drilling has various methods that from different aspects such as crushing mechanism, type of used energy etc., is divided to several types containing hand held drilling, percussive drilling, cable-tool drilling, rotary (or circular) drilling, percussive-rotary drilling and core drilling. Unlike the direct circulation drilling system (DC) in the reverse circulation drilling system (RC), the drilling fluid moves the annulus between borehole wall and the drilling pipe and comes back with the drilled pieces along inside the drilling pipe. The exploratory drilling system of RC by conducting powder samples with high purity and fast drilling rate, is a great help to the velocity and accurate of exploration of ore deposits. Samples produced in this method are in the form of soil and rock powdered and rock fragments of the drilled part, which may be dry or with little moisture. The air flow inside the cycle causes the collected powder sample to be often dry but sometimes is wet due to groundwater or drilling mud. Drilling is one of the most costly mining processes. Therefore, the most important goal in drilling engineering is to reduce costs, and the best possible decision to optimize the cost of drilling is to choose the best possible drilling method. Based on the field data, cost of drilling for each meter of a soft rock (e.g. travertine) by core drilling and direct drilling methods are about 3.3 and 1.2 times of the RC method, respectively. Also the cost of drilling, for each meter of a hard rock (e.g. granite) by core drilling and direct drilling methods are about 2.6 and 1.3 times of the RC method, respectively.
Materials and methods
In the present research, reverse circulation drilling (RC) has been compared with other important, common and practical drilling methods, such as direct circulation and core drilling methods in terms of various criteria containing drilling (time) rate, price (cost), type and quality of acquired samples and performance efficiency of drilling. Also, as a field study in this research, deep drilled boreholes with RC and core drilling methods in the gold mine of Khomein-Akhtarchi located in the Markazi province, were investigated and compared from different aspects. At the end, the ability to select the most appropriate drilling method among the variety of methods was studied. The study region is located at 25 km northeast of Khomein city in the Markazi province. This region consists of two exploration areas of Zarmadan-Akhtaran1 with the area of 13.21 square kilometers and Zarmadan-Akhtaran2 with the area of 2.85 square kilometers. Access to the Akhtarchi gold region is possible through the Khomein-Shahabiyeh (Goldsat)-Mahallat road. In the mining region, the Permian rock complexes include dolomite, dolomitic limestone from brown to dark gray, black Irony sandstone and white to milky limestone known as p^ds, p^dl and p^l units in the geological maps.
In the studied region, several deep boreholes, most of them by RC and some of them by core drilling methods have been drilled. In general, by now in the Akhtarchi gold zone in the Zarmadan-Akhtaran2 area 54 powder boreholes have been drilled through RC method called by RC1 to RC54. Also, there are 25 core drilling boreholes, 18 boreholes called by BH1 to BH18 in the Zarmadan-Akhtaran1 area and 5 boreholes called by BH1 to BH5 in the Zarmadan-Akhtaran2 area. During drilling operations, Permian and Cretaceous rock units have been encountered. The details of drilling via RC method for 4 boreholes with numbers 50, 51, 53 and 54 have been accurately taken. The measured drilling times were obtained from drilling personnel of the mine through the questionnaire which they were weighted mean if needed.
Results and discussion
The average drilling time for each meter of rock in boreholes 53 and 54 is 2:12 and 2:54 minutes, respectively. In both cases, the time duration is very short and this feature is one of the advantages of the RC drilling method. The longer average duration of drilling for each meter of rock in the borehole 54 than 53, is due to the depth of the borehole 54 and the hammer problem of the drilling machine during the drilling this borehole. In Table 1, the average duration of drilling operation per meter of rock in the Akhtarchi gold mine is given according to the type of rock (lithology) at definite depth intervals, on the basis of field studies. According to this table data, the duration of the drilling for each meter of rock in the greater depths increases that the reasons for increasing the duration of drilling for each meter of rock in greater depths are the difficulty of drilling due to the increasing length of rig, the reduction of transient energy to the bit, the probability of greater borehole declination, compaction increasing and as a result increasing the strength of rocks and more hydrostatic and lithostatic pressures in the great depths meanwhile at a great depth, the probability of capturing the drilling rig is too high. Also the cost (the time price) of drilling per meter of rock in this mine based on the dip and depth of drilling is about 1300 to 2000 thousand Rials by the RC method, against 2620 to 4250 thousand Rials by the core drilling method.
The results of the present research indicate that the RC drilling in comparison with other drilling methods, especially conventional and applied ones in terms of drilling costs and drilling rate (time) is highly desirable while is desirable regarding depth of drilling, the type and quality of the acquired samples and the overall efficiency of drilling performance. Although the core drilling method with the ability to drill very deep boreholes obtaining cores in terms of the type and quality of the acquired samples, as well as the depth of the drilling is the most desirable, but for exploration drilling (especially in the detailed exploration stages), deposits with low-grade and very little mineral indices (like gold mine of Khomein-Akhtarchi), and hence the large sample sizes are needed, employing RC drilling method having comparative advantages is economic.
Conclusion
Regarding the use of RC drilling method in the case study, the gold mine of Khomein-Akhtarchi, it was found that the RC method compared to the core drilling method, in terms of the duration of drilling operations or the speed of advance (the rate of penetration in the rock), drilling costs and efficiency of performance is desirable. Also, according to the type of mineral deposit (gold type), which is low-grade and the indices of the mineral are very low, therefore the large sample sizes are needed, thus, in terms of the type of obtained samples, employing RC drilling method in this case, is accounted a very important advantage related to the DC method (in terms of accuracy) and core drilling method (in terms of cost). The results of this research are useful for all users of drilling operations, including drilling engineers and technicians, engineering geology and geotechnical practitioners, mineral exploration engineers, groundwater aquifers and hydrocarbon reserves (oil and gas) to choose the optimal drilling method under different environmental and economic conditions based on criteria such as the purpose of drilling operations, costs, progress rate, type and quality of the yielded samples and the efficiency of drilling operation. Also, the use of RC drilling method has the advantages over the other drilling methods to be suggested for exploration of low-grade deposits such as gold, silver and copper, especially in the final stages such as detailed and mining exploration.
 

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Introduction
Dispersive soils are problematic and they cause a great many of local damages and destructions in hydraulic structures such as dikes and irrigation channels. The correct identification and recognition of divergence are fundamental measures taken in line with preventing the early destruction of the hydraulic structures. The soil improvement using lime, especially in clayey soils (CL), brings about an increase in the optimum moisture percentage, reduction of the maximum dry unit weight, reduction of swelling potential, increase in the strength and elasticity module. The effect of lime on soil can be classified into two groups, namely short and long-term stabilization. Raise of the soil’s workability is counted amongst the short-term modification measures and it is the most important factor in the early improvement stages. The increase in the strength and stability can be considered as the lime utilization on long-term results occurring during curing and afterwards. Also, according to the reports, swelling and damages occur in the lime-stabilized soil containing sulfate. The effective role of the iron furnace slag has been well recognized in increasing the strength against sulfates and corrosive environment conditions of the mortar containing lime and sulfates.
Material and methods
Adding the slag products of the melting furnaces and lime is a method used to stabilize dispersive soils. The present study makes use of a mixture of clay featuring low plasticity with 1% and 2% lime and slag, for 0.5%, 1%, 3% and 5% of the weight, to improve dispersivity, shear strength and plasticity. The samples were kept in constant temperature and humidity for a day and then were subjected to direct shear, uniaxial strength and pinhole tests.
Results and discussion
It was observed based on pinhole experiment of the initial dispersive soil sample, denoted as D1, that the sample, shown by ND2, containing lime, for 2% of the weight, and slag, for 5% of the weight, turned out to have become non-divergent. The results of the direct shear test showed that the adhesion coefficient of the slag-free samples stabilized using 1% lime has been increased from 0.238 kg/cm² to, respectively, 0.251 kg/cm², 0.373 kg/cm², 0.41 kg/cm² and 0.48 kg/cm²  per every 0.5%, 1%, 3% and 5% slag added. The adhesion of the samples stabilized using 2% lime as determined in the direct shear experiment were 0.615 kg/cm², 0.671 kg/cm², 0.724kg/cm² and 0.757kg/cm² per every 0.5%, 1%, 3% and 5% slag added. Also, the internal friction angle of the samples stabilized using 1% lime was found an increase from 14.3° for slag-free samples to 18.11°, 21.3°, 21.86° and 21.92° per every 0.5%, 1%, 3% and 5% added slag. As for the samples stabilized using 2% lime, the internal friction angles were found in direct shear test equal to 23.15°, 23.53°, 23.76° and 24.12° per every 0.5%, 1%, 3% and 5% slag added. The uniaxial strength of the slag-free samples stabilized using 1% lime was found an increase  from 1.0014 kg/cm² to, respectively, 1.0616 kg/cm², 1.0782 kg/cm², 1.2127 kg/cm² and 1.2246 kg/cm² per every 0.5%, 1%, 3% and 5% slag added. The uniaxial strength rates has been determined in the direct shear test of the samples stabilized using 2% lime were 1.1367 kg/cm², 1.1885 kg/cm², 1.2322 kg/cm² and 1.2872 kg/cm² per every 0.5%, 1%, 3% and 5% slag added. The amount of axial strain of the slag free samples stabilized using 1% lime was found decreased from 9.6842% to, respectively, 9.3333%, 9.2683%, 9.6364% and 8.4444% per every 0.5%, 1%, 3% and 5% slag added. Moreover, the axial strain amounts obtained for the samples stabilized using 2% lime were 7.7333 kg/cm², 7.6316 kg/cm², 7.1517 kg/cm² and 4.7619 kg/cm² per every 0.5%, 1%, 3% and 5% slag added.
The study results indicate that slag and lime have the capacity of improving the studied soil’s dispersivity. Furthermore, it was figured out that adding slag to the soil causes an increase in the soil strength and improves the shear strength parameters. It can be stated according to the observed results that the use of slag, a byproduct of iron smelting industry, as a substitute for a given percentage of lime is effective on the reduction of the clay soil’s divergence potential. The results of the experiments carried out to determine Atterberg limits are suggestive of the idea that the increase in the slag and lime fractions brings about a decrease in the liquid limit and plasticity and improves the plasticity properties of the soil. The reason why the soil plasticity has been reduced after being mixed with lime and slag is the cationic exchange and coarsening of the soil texture. Addition of lime to the soil causes an increase in the plasticity limit and a reduction in the liquid limit. Therefore, the plasticity index is decreased and the plasticity characteristics of the soil are improved. Adding 1% lime to the dispersive soil leads to small reduction of the liquid limit from 32.43% to 31.73%, a small increase in the plasticity limit from 13.42% to 14.66% and a insignificant decrease in the plasticity index from 19.01% to 17.07%.

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Introduction
Pavement layers as a part of road structure play an important role and provide a flat and secure surface. Subgrade layer could act as a compacted embankment, natural or stabilized ground. Subgrade is a foundation of pavement layers, and it withstands all of loads due to vehicles that are transferred from upper layers (i.e., subbase, base and asphalt layers).Therefore, constructing pavements with bearing capability, high durability, quality, and maintenance in proper operating conditions is very important. However, suitable materials for constructing pavement layers are not available, and improvement techniques should be employed for them. Generally, different methods such as mechanical or chemical are available for improvement. Nowadays, geosynthetic materials such as geotextile and geogrid are used to optimize and enhance the bearing capacity of pavement layers. The present study is aimed to investigate the effects of geotextile applications on bearing capacity of clay-gravel mixtures in pavement layers.
Material and Methods
In this research, materials were prepared from Barandouz area. Clayey soil was mixed with gravel in 25, 50 and 75 percentages (by weight). Geotextile was woven and made of polypropylene (with commercial name Fibertex-F-32). Geotextile effects in mixture were evaluated in two conditions. Position number one indicates the arrangement of geotextile.  This means, at first, one geotextile layer was embedded in the middle of materials. Then, two and three geotextile layers in equal depths from each other were used in soil mixtures. Position number two shows the mixing pieces randomly. This means that geotextile pieces in 1×1 and 5×5 cm² were prepared and were randomly mixed with materials in 1, 2 and 3 percentages (by weight). For evaluating geotechnical behavior of improved clay-gravel mixtures, compaction and California bearing ratio test (CBR) (in dry and saturate conditions) based on ASTM were performed.        
It should be noted CBR test in dry and saturate conditions were carried out in three different compaction energies (i.e. 10, 25 and 56 blow count for per layer). Moreover, CBR was evaluated for piston penetration at 2.5 and 5 cm in the specimen.
Results and discussion
The findings of this study could be summarized as:
1. Results of compaction test showed that, in the unimproved position, with increasing gravel content in clay, maximum dry unit weight (γd_max) has been increased, while simultaneous optimum water content (w_opt) decreased.
In the improved position, in the first mode, when a geotextile layer was embedded in the middle of the specimens, γd_max reached to its upper value, whereas w_opt reached to its minimum value. On the other hand, with an increase in the number of geotextile layers in clay-gravel mixtures, dry density has been decreased, but optimum water content increased. Furthermore, in the second mode, when geotextile pieces with 1×1 and 5×5 cm² were randomly mixed in the specimens, the findings revealed that geotextile pieces with 1 cm² areas and 1% by weight in clay-gravel mixtures increases γd_max and reduces w_opt.
2. In dry and saturate conditions, California bearing ratio (CBR) test result displayed that in the unimproved condition, with an increase in gravel content in the clay, CBR value has been increased. In the improved situation, in the first mode, when a geotextile layer was embedded in the samples, CBR had a maximum value in all of the compaction energies even though it is reduced as the number of layers increased. In the second mode, when geotextile pieces in 1×1 cm dimensions with 1% (by weight) were randomly mixed with the specimens, CBR value reached at high.  In contrast, with increasing dimensions of pieces and percentages in the presence of geotextile in clay-gravel mixtures, CBR values declined.  Therefore, it can be concluded that, according to Code 234 (Iran Highway Asphalt Paving Code), the application of one geotextile sheet in the middle of materials or geotextile pieces in 1×1 cm dimensions with 1% (by weight) random mixing  is suitable for subbase and base layers in pavement design.
3. CBR test results in the saturate condition in clay-gravel mixtures illustrated that, in the non-reinforced condition, with an increase in clay content in specimens, swelling value keeps rising sharply. On the contrary, in the reinforced position with embedding a geotextile layer in the middle sector of samples or through adding geotextile pieces (1 cm²) with 1 % content  (by weight) to the specimens, the rate of swelling significantly decreased.   
Conclusion
To sum up, the main objective of the present study was to investigate the impact of geotextile applications on bearing capacity of clay-gravel mixtures in pavement layers. The findings demonstrated that when geotextile as a layer was embedded in the middle part of specimens or as pieces with 1×1 cm dimensions and 1% content (by weight) was randomly mixed with the mid materials, the bearing capacity of the reinforced specimens was enhanced.  In contrast, in the saturate condition, swelling potential significantly was reduced. It is noteworthy to mention that 1 cm² pieces of geotextile is more effective than the layers. This is due to the fact these pieces make aggregates closer to each other. Thereby, minimum void ratio (e_min) reaches its least value, the structure of grading improves, and the contacts between particles and geotextile pieces rise. As a suggestion for further research, it looks promising to evaluate the dynamic properties and the behavior of the improved materials with other geosyntheticses.
 

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Introduction
Drill-bit selection is one of the most important aspects of well planning due to the bearing it can have on the overall cost of the well. Bit selection in conventional and slightly inclined wells is a very delicate and complex process. In high angle and horizontal wells it is even more difficult. Historically, drilling engineers have selected bits on the basis of what has been worked well in the area and what has been determined to have the lowest cost run from offset bit records. Often the best bit records were not available for evaluation, because the best bit may not yet have been run, may have been run by a competitor or the engineer was new to the area. As a result the bit program was generally developed by trial and error and at significant additional costs for a large number of wells. In most cases the optimum program was never reached because there was nothing to predict that a bit selection change could further reduce the cost of the well. In this study, an alternative solution approaches using the concept of the power of data mining algorithms to solve the optimum bit program for a given field is proposed.
Material and methods
It has been considered an offset well to be drilled outside the known boundaries of a known field. For this purpose, the seventh well (X-7) of the same field was used as a verification point. The data was trained using the well log and rock bit data of six wells located in the field and the real well log data of well 7 was input as unknown data. These depths are selected based on reported rock bit program. When compared to the real data, it could be observed that the models (adaptive neuro fuzzy inference system, K-nearest neighbors, decision tree, Bayesian classification theory and association rules) estimates the formation hardness accurately. This minor discrepancy was also present with the company’s suggested rock bit program, which was based on the previous wells’ rock bit data.
Results and discussion
In this paper, data mining algorithms for optimum rock bit program estimation is proposed. The accuracy and efficiency of the developed data mining algorithms (adaptive neuro fuzzy inference system, K-nearest neighbors, decision tree, Bayesian classification theory and association rules) that requires sonic and neutron log data input was tested for several real and synthetic cases. In the case of a development? well to be drilled outside the known boundaries of a field the model estimated rock bits with properties that consider the formation hardness correctly but slightly underestimated further rock bit details. The models also produced reasonable rock bit programs for an advance well to be drilled within the known boundaries of a field and a wildcat well drilled in a nearby field with similar rock properties to the training field. Thus it was concluded that the developed adaptive neuro fuzzy inference system is suitable as a front-end system for rock bit selection that could help engineers in decision-making analysis.
Conclusion
Optimum bit selection is one of the important issues in drilling engineering. Usually, optimum bit selection is determined by the lowest cost per foot and is a function of bit cost and performance as well as penetration rate. Conventional optimum rock bit selection program involves development of computer programs created from mathematical models along with information from previously drilled wells in the same area. Based on the data gathered on a daily basis for each well drilled, the optimum drilling program may be modified and revised as unexpected problems arose. The approaches in this study uses the power of data mining algorithms to solve the optimum bit selection problem. In order to achieve this goal, adaptive neuro fuzzy inference system, K-nearest neighbors, decision tree, Bayesian classification theory and association rules were developed by training the models using real rock bit data for several wells in a carbonated field. The training of the basic models involved use of both gamma ray and sonic log data. After that the models were tested using various drilling scenarios in different lithologic units. It was observed that the adaptive neuro fuzzy inference system model has provided satisfactory results.
 
 

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Introduction
 Analysis of time, location and magnitude of foreshocks and aftershocks has been one of the most important cases for experts in various scientific fields such as: seismology, structural engineering and crisis management, and other interrelated fields. Since this analysis and the result of studies on seismotectonic and cases of earthquakes help us identify the foreshocks and aftershocks with the goal of decreasing losses and nervious stress of the injured community in quake-stricken areas and skilled crisis management. The cause fault of earthquake plays the important role in foreshocks and aftershocks of the earthquake. So, study on fault behaviour is a suitable method for analyzing and routing the basic parameters of foreshocks and aftershocks. Also, foreshocks and aftershock are important parts of any earthquake in a seismic area. The analysis of the basic parameters of the foreshocks is one of the most practical researches for reducing the risk of earthquakes. The identification of behavioral pattern of foreshocks can help researchers detect the active fault conditions for the occurrence of earthquakes in different areas. The present study is concerned with the study of behavioral patterns earthquakes, foreshocks, and aftershock of Zohan earthquake. Experience of large aftershocks in different parts of the world indicates that, following earthquakes and depending on seismic-tectonic conditions, large aftershocks are likely to occur in the earthquake-effected zone, which will aggravate the damage caused by earthquakes (Omi et al., 2013). The main factor contributing to the worsening of damage caused by aftershocks is the performance of structures that are weakened but not destroyed by main earthquakes and are, thus, highly likely to be destroyed by large aftershocks (Saket and Fatemi Aghda, 2006).
Material and methods
The present paper makes use of data collected in a real earthquake and similar expriences in other earthquakes for presenting a practical pattern for predicting primary earthquake patterns, determining the location, magnitude, and time of aftershocks. The target of this case is decreasing the effects of earthquake. To this end, we used the results from studies on basic parameters of foreshocks and aftershocks of Zohan earthquake, and 2012 earthquake in South Khorasan province. The rationale for selecting the aforementioned studies is: location of event, the Zohan earthquake, had been identificated as an area with high risk for the occurrence of earthquakes, although there has been no wide-scale earthquake in this area in the last two decades. These conditions are important causes for more concentrated studies on this area because there is a high chance for wide-scale earthquakes striking this area.
Result and Discussion
In this part of research, we conduct a study on the location, magnitude and depth of foeshocks. Some of the world-wide research suggested that these data can help to predict the time of  mainshocks. Studies conducted on the variations of frequency in foreshocks can follow this goal.
In this paper, the available statistical data such as periodical variations of seismicity in the weeks leading up to the main shock can be used as a tool for estimating the approximate time of a future important earthquake. The weekly variations of seismicity before Zohan earthquake indicate a relative increase and then decrease within a 100 km radius around the epicenter of the main shock.
 
Table 1: Variations of frequency of foreshock based magnitude before Zohan earthquake

Week before main shock	Frequency of foreshock in the Radius of 100Km from main shock	Frequency of foreshock(with M>2.5) in the Radius of 100Km from main shock
6	0	0
5	1	1
4	1	0
3	2	0
2	5	3
1	2	0

 
Studies on numerous earthquakes in Iran and other regions in the world show that the distribution of aftershocks can be related to fault type or the direction of principal stress (Saket and Fatemi Aghda, 2006) and (King et al., 1994). Whereas maximum Coulomb stress change is related to maximum principal stress in earthquakes, the concentration of aftershocks can coincide with the direction of maximum principal stress (σ₁) of the causative fault in mainshock. Considering the direction of maximum principal stress and its adaptation to the scattering of aftershocks, the above hypothesis is confirmed.
Also studies on frequency changes and seismic quiescence of small aftershocks help us in predicting future aftershocks. The results the of presented research by Itawa (2008) on the World earthquake catalogue suggest that seismic quiescence theory is true for different regions of the world. Based on the results of the  study mentioned above, this case can be used as a tool for predicting large aftershocks in Zohan earthquake.

Fig 1. Adaptation of direction of maximum principal stress with scatering of the aftershocks of Zohan earthquake. a: direction of maximum principal stress (σ₁) of the causative fault in mainshock. b- scaterring of the aftershocks
Table 2: Seismic sequience versus magnitude of aftershocks

Row	Seismic Quiescence for aftershocks	Aftershock Magnitude	Data and Time of aftershocks
1	13	3.0	2012/12/05 17:21:03
2	36	3.4	2012/12/05 17:57:03
3	161	3.1	2012/12/05 20:38:09
4	3906	3.9	2012/12/08 13:44:19

In addation, frequency of aftershocks and certain time distance (seismic quiescence) between their can use precursors for detecting the time of large aftershocks. The relevant analysis in this study showed that methods such as: time series beside seismic quiescence can help in conducting a more accurate time forecast of large aftershocks.
Conclusion

• The results of this research suggest that we can identify some of the charactristics of the main shock by focusing on location, magnitude and depth of foeshocks.
• In Zohan earthquake, the direction of maximum principal stress is adpated to the scattering of aftershocks, and this case suggests that there is a specific relationship between them.
• The relevant analysis in this study showed that the methods such as: time series beside seismic quiescence can help conduct a more accurate time forecast of large aftershocks../files/site1/files/144/saket.pdf

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In Yazd Darreh-Zereshk copper deposit geophysical data containing magnetic, resistivity and induced polarization have been surveyed and 25 boreholes have been drilled in the area. In the present research, inversion and processing of geophysical data as well as their qualitative and quantitative accordance with boreholes assay data have been carried out. To achieve the goal first, total magnetic intensity map after applying necessary filters and processing, was mapped to identify surface and deep expansion of anomalies on it. Drawing the anomaly profile of magnetic stations surveyed along 4 geoelectric profiles shows that most of the magnetic anomaly zones have high chargeability and low resistivity that indicates the qualitative compatibility of magnetic and geoelectric data, as a result increasing the probability of mineralization in the area. Afterward  on the basis of qualitative interpretation of geoelectrical sections, optimal locations of drilling on the each profile were proposed. Plotting mineral deposit cross-section along the geoelectrical profiles using the boreholes assay data, revealed that drilling of some boreholes located on the geophysical profiles haven’t been based on the results of geophysical operation, carried out without any right logic, purpose and design. In general, the qualitative accordance of the results of geoelectrical operation with the boreholes assay data showed a pretty good qualitative accordance. Also investigation of linear correlation coefficient value between inverted geophysical data and borehole assay in a specific same range after a same definite gridding and interpolation of their values, overall indicated a relatively good quantitative accordance (between 0.4 and 0.7)../files/site1/files/151/1.pdf

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Chahar-Gonbad region of Kerman province is geologically located in the southern part of central Iran zone, dominantly in Uromieh-Dokhtar volcanic belt. In this region, many high potential prospects, specially Cu-Au mineralization, have been detected during large scale exploration and reconnaissance phases. In this paper, remote sensing and field geophysics were used for alteration mapping on the surface and ore body delineation on the subsurface, respectively. To this end, we used an ASTER satellite image and different maps were generated by spectral technics such as false color composites and spectral ratios. Results showed argillic (and phillic) alteration in Bab-Zangoeie area is surrounded by propylitic alteration, which could be a promising evidence for Cu mineralization. Integrating these results with previous exploration studies led to selecting target area selection for ground study and field geophysics. We used both induced polarization (IP) and resistivity (RS) methods as two powerful geoelectrical methods by a pole-dipole array along four profiles. After preprocessing analysis, forward and inverse models were constructed in 2D section and 3D overlay model of joint IP/RS anomalies were constructed. Based on the obtained results, the deposit in depth where we proposed drilling targets. Further drilling operation have proved the mineralization in our proposed targets../files/site1/files/152/%D9%86%D8%B8%D8%B1%DB%8C.pdf
 

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Existence of sodium elements in fine-grained of some soils causes dispersive phenomenon in them.  Failure to accurately identify dispersive clays leads to damage because dispersive clay soil particles disperse under certain conditions and wash away quickly. This research assesses dispersive degree of outcropped soils in southeast of Yazd. Finally, the modification of soil dispersive potential was investigated by using nanocellulose.  After performing a series of physical, chemical and mechanical tests, characterization/ specification of the studied soils were determined. Then dispersive degree was specified by conducting chemical, pin hole, crumb and double hydrometer tests. Finally, soil dispersivity stabilization was performed using sample preparation with 0.5, 1 and 1.5% nanocellulose. The results showed that the studied soils have moderate dispersive in borehole A and extreme to slightly dispersive in borehole B. Therefore, it can be concluded that the closer we get to the center of the plain, the greater the dispersibility. The results of the dispersibility stabilization soil tests indicate that the optimum moisture content and dry specific gravity increases and decreases. Uniaxial strength and CBR increases. Also, it shows that the increase in nanocellulose has a positive effect on the modified samples and improves the soil dispersibility in this area../files/site1/files/152/%D8%B2%D8%A7%D8%B1%D8%B9.pdf
 

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Extended Abstract