Journal of Engineering Geology

---

A new approach is suggested to determine the permanent deformation of slope under seismic loading based on the horizontal slices method and limit equilibrium analysis. A comparison of the analytical results obtained from the proposed method for 3 sample slopes with those of previous research results is performed. The analytical method presented can be used to calculate yield acceleration, seismic coefficient of horizontal acceleration, permanent deformation and angle of failure wedge for slopes. Also, the stability analysis can be performed by proposed method. It was concluded that the horizontal slices method by analytical procedure proposed reliably calculates the permanent deformation of slopes.

---

The ever increasing growth and development of the metropolitan city of Karaj in recent years has placed implementation of basic studies on Alluvium of Karaj Plain on the top of significant priorities of the region’s development projects. Therefore, in the present paper, the alluvium of South Karaj was studied based on relevant numerous geotechnical laboratory and field tests. In this regard, an area from Pol-e Fardis to Serāh-e Andishe with a length of 10 km is selected and the geotechnical engineering features of this area were taken into careful consideration and study. The carried out studies divide South Karaj Alluvium into five independent parts whose engineering description are presented. On the other hand, since the results of most of relevant laboratory and field tests have been collected, some relations for calculating Elasticity Modulus, Soil Inner Friction Angle as well as other geotechnical parameters in South Karaj Alluvium are introduced. Finally, the process of soil classification in South Karaj Alluvium is compared with the same process in other regions of Karaj, and, given the soil engineering features of Southern part of South Karaj Alluvium, some suggestions are presented for optimization and facilitation of future development projects in south Karaj Alluvium. Geotechnical studies.

---

Desiccation cracking commonly occurring in compacted clayey soils typically used as landfill liners can result in poor hydraulic performance of the liner. In this research, a simplified image processing technique was developed in order to characterize desiccation cracking intensity in compacted clayey soils. Three pairs of compacted clayey soils were studied in a relatively large scale experiment to evaluate the effect of geotextile cover on desiccation cracking under real-time atmospheric conditions. Digital images were taken from the surface of soils at certain time intervals for 10 months and were analyzed to determine crack intensity factor (CIF). The key parameter in identification of cracks as accurately as possible was found to be sensitivity. Calibration process was based on using %20 of the images with different crack intensities whose crack dimensions and therefore CIF values have been already measured to compare to program output. A calibration coefficient for sensitivity was accordingly determined based on the average difference between the sensitivity introduced by the program and the actual sensitivity calculated based on an overlaying process. Result of verification of this methodology indicated that it can be reliably used to determine CIF of compacted clay soils in a simple yet accurate manner.

---

All rockfill materials subjected to stresses above the normal geotechnical ranges exhibit considerable particle breakage. Particle breakage and crushing of the large particles to smaller ones result in a lower strength and higher deformability. The breakage of particle that is observed in the large scale triaxial tests, is usually expressed quantitatively by the Marsal breakage index, . This paper presents a method for calculating at any axial strain level in the large triaxial tests. The model used Rowe’s minimum energy principle ratio. The key parameter in modeling , is the friction angle which excludes dilation and breakage effects, . The results indicate that the internal friction angles at confining pressure equal and less than 200 kPa at the constant volume state is a unique value. Moreover, there is a linear relationship between the variation of energy spent on particle breakage to Marsal Breakage index with confining pressure, at failure axial strain.

---

Tunnel boring machines (TBM) are widely used in excavating urban tunnels. These kinds of machines have different types based on supporting faces and tunnel walls. One type of these machines, is the Earth Pressure Balance (EPB) type that was used in excavating the Line 1 Tunnel of Tabriz Metro. Different parameters such as geological conditions, rock mass properties, dip and machine specifications affect the efficiency of the machine. One method of predicting the efficiency of these machines is to estimate their penetration rates. In this study the value of TBM penetration rates are predicted by an artificial neural network. Predicting of this parameter is so effective for conducting in high risk regions by understanding the time of facing to these regions. The main result of this study is to forecast the penetration rate with an acceptable accuracy and to determine the effective parameters through sensitivity analysis measured by an artificial neural network.

---

In the karstic areas, detailed studies of phenomena such as seepage of water from hydraulic structures and land subsidence in the residential and quarry areas  is of  higher importance. In this study, the dissolution rate constant of gypsite samples of Gachsaran Formation, obtained from the Chamshir dam reservoir, were measured equal to 0.24×10^-3 cm/sec. Then, the changes of amounts of joint apertures using theoretical and experimental (by changes of joint water flowing and direct measurement) methods were calculated. The results showed that the predicted aperture for joints calculated through theoretical method is less consistent with the measured value of the changes of joint water flowing while the value measured by direct method (measured using a caliper) compliance is higher. Also based on research findings, if gypsites of the dam reservoir are exposed to the water flow, the amount of aperture of a joint with 0.5 cm initial opening will increase to 10 cm after about 278 days. This increase in joint aperture compared with the useful life of the dam draws for special attention to water tightening of dam reservoir.

---

In this paper, using Mononobe & Okabe method, seismic force and its effects on thin masonry retaining wall inside structural frame (Masonry retaining infill) are presented. In this method, retaining wall has been assumed to be rigid and the prevailing failure mode is sliding of wall bed joint or wall rotation around its toe, whereas the prevailing failure mode of masonry retaining infill is usually flexural cracking in middle zone of wall under out of plane seismic force. In this case, the seismic force distribution is important. Accordingly in this paper, a distribution for seismic forces on masonry retaining infill has been proposed. Also with regard to out of plane behavior of masonry retaining infill in terms of strength and acceptance criteria aspect, failure in body of wall due to out of plane loads has been analyzed. Then, the desired seismic rehabilitation method in case of vulnerable masonry retaining infills has been presented and as a practical example, results of the proposed method with the results of numerical software have been controlled. Finally, according to various conditions predicted for masonry retaining infills, Seismic Retrofit solutions are presented for practical applications.

---

With respect to development of underground structures and their high construction costs in intra- and inter-municipal transportation, it is necessary to study the stability of such structures. In this research, tunnel stability of Mashhad Metro line 2 with 17 km length is studied. First, the type of sediments and geotechnical properties in Mashhad Plain are investigated. The SPT profiles were prepared using Rock Work 2006 software. The soil classification tests and XRD results show that the soils in this line are mostly clay such as Illite and Kaolinite types. Afterwards, because most of the soils in this line are characterized as fine grained, the ground settlement using PLAXIS V8 software was performed. According to the numerical modeling and the depth of tunnel, the optimum depth for tunnel was determined.

---

The shape of slip surface of the wedge creating lateral thrust on rigid retaining walls plays an important role in the magnitude, distribution, and height of point of application of lateral thrust.  Considering the shape of slip surface as linear, circular, logarithmic spiral, or a combination of them has been used in the literature. In the Coulomb lateral earth pressure method, a linear distribution of soil pressure on retaining walls is tentatively assumed and thus the point of application of total thrust is placed at one third of the wall height from the wall bottom. However, some experimental studies have revealed non-linear distribution of lateral earth pressures and that the point of application of resultant thrust is placed upper than one third of the wall height. In the present study, a plasticity equation is used to determine the reaction of the stable soil on cohesionless backfill supported by a retaining wall using an empirical equation derived from experiments performed in the field by others. A new analytical solution for determining the total resultant thrust on the wall is introduced and the distribution of pressures and the point of application of total thrust are computed. The results have been compared with some analytical methods, experimental data, and also with available data reported from field, demonstrating the accuracy and capability of the developed method. The results show that the distribution of the active lateral earth pressure is nonlinear and the point of application of total thrust is located about 0.42H from the wall bottom (H=wall height). In addition, the application point of total thrust is nonlinear function of soil-soil, wall-backfill soil friction angels and the height of the wall

---

Construction of asphaltic core dams is a relatively novel method especially in Iran. Iran is located in a region with high seismicity risk. Therefore, many researchers have focused on the behavior of such types of dams under earthquake loading. In this research, the behavior of asphaltic core rockfill dams (ACRD) has been studied under earthquake loading using nonlinear dynamic analysis method and a new method is presented to assess seismic stability of these types of dams in earthquake conditions. Based on nonlinear dynamic analysis, the current study attempts to provide an appropriate criterion for predicting the behavior of earth and rockfill dams considering real behavior of materials together with actual records of earthquake loading. In this method, the maximum acceleration of the earthquake record (PGA) increases until instability conditions. Finally, a new criterion is presented for evaluating seismic safety of ACRDs via demonstrating curves of the crest's permanent settlement and maximum shear strain against maximum earthquake acceleration. Results of the proposed criteria can assist designers of asphaltic core dams to predict dam stability during earthquake event

---

One of the geotechnical hazards in the tunnels under high overburden and high in situ stresses is the phenomenon of rock burst. Rock burst is a typical geologic phenomenon caused by excavation in rock masses. In this phenomenon, because of stress released and explosion in rock masses, they are broken as large and small pieces and are distributed, so that leads to damage of peoples or equipments. Therefore, familiar with this phenomenon and its mechanism of occurrence, is need to analyze this issue. The second part of water supply Karaj-Tehran tunnel with a length of 14 km and about 4.5 m diameter is located in Tehran province. Rock burst analysis has been carried out in the tunnel from kilometer 6 to 9.5 that is critical section because of high overburden (up to 800 m) and presence of faults and crushed zones. In this paper, for predicting rock burst in the critical section of second part of Karaj-Tehran tunnel, four criteria including, Strain energy, Rock brittleness, Seismic energy and Tangential stress criterion are used. Analysis results show that units with high overburden have high possibility of rock burst. 

---

In this research, one of the new methods for seismic landslides hazard zonation (CAMEL) to predict the behavior of these types of landslides have been discussed.  It is also tried to eveluate this method with the proposed Mahdavifar method.  For achieving this result, the influence of  Sarein earthquake (1997), have been selected as a case study. In order to apply seismic hazard zonation, the methodology of Computing with Words (CW), an approach using fuzzy logic systems in which words are used in place of numbers for computing and reasoning is employed. First, the required information which includes disturbance distance, ground strength class, moisture content, shake intensity, slope angle, slope height, soil depth, terrain roughness, and vegetation have been collected using air photos, Landsat Satellite images, geological and topographic maps, and site investigation of the studied region. The data is digitized and weighted using Geological Information System (GIS). At the next step, the hazard rate and areal concentrations with respect to landslide types are calculated using CAMEL program and then, landslides hazard map produced by the above mentioned method is compared with landslides occurred as a result of Sarein earthquake. Finally, for evaluating on prediction of the earthquake-induced landslides, empirical comparison have been done between CAMEL and Mahdavifar methods.

---

Wave velocity and attenuation are among the most important attributes of stress waves that propagate through geomaterials. Utilizing these attributes, it is possible to acquire useful information about porous geomaterials such as soil and rock and also the fluids that saturate the pores of geomaterials. The key point in order to gain this information is to establish an accurate link between field measurements of wave attributes and physical properties of geomaterials’ skeleton and pore fluid. The pore fluids and their inhomogeneous distribution fluid are among factors that affect wave velocity and attenuation to a considerable extent. Patchy saturation of pores which occurs on the scale larger than grains size but smaller than wavelength is one of the reasons that causes inhomogeneity in pore fluid distribution. The influence of such inhomogeneity is studied in present paper. Two different attenuation mechanisms including relative movement of fluid with respect to solid phase and also attenuation caused by grain to grain contact are implemented to fully assess wave attenuation. It is observed that the former attenuation is more dominant at higher frequencies compared to the latter attenuation.

---

One of the major challenges in tunneling is the excavation in regions with high potential of squeezing and in the case of application of full face boring machines evaluation of the required thrust in these regions is inevitable. The Beheshtabad water conveyance tunnel with 65 km in length is considered for transferring one billion cubic meter of water annually to the central part of Iran.  According to geological investigation there is a high potential of squeezing in the 19^th section of tunnel. In this article, the thrust evaluation methods are investigated and the required penetration force is calculated. Then the numerical procedure applicable to thrust evaluation in the 19^th section is discussed and the results are analyzed.  In addition, the required thrust to overcome shield skin frictional resistance using Ramoni's method (2010) is computed and the outputs are compared to numerical ones. As a result of numerical simulation, in order to utilize double shield TBM for the sections of 29030-31600 km and 34900-37490 km, it is required to overcut 3 cm for the favorable geomechanical locations and 10 cm for the unfavorable geomechanical conditions. Decision on the application of full face boring machines in the section of 31600-34900 km could be made providing long term parameters of host rock were determined via performing additional in situ tests in the exploration gallery.  

---

Marl rocks are from weak rocks which cause some problems due to high swelling and efflorescence capability, low resistance and durability in construction of engineering structures. Creation of these problems is due to inadequate recognition of engineering geology properties of these rocks. Hence, in this research for determination of the physical and mechanical parameters of marl rocks of Safa dam site, Aterberg limits, density, porosity and moisture percent, uniaxial compressive strength (UCS), direct shear, swelling and three axial compressive strength tests and X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses were performed on available samples from excavated bores. Results of experiments indicate that the type and contents of minerals and percentage of calcium carbonate in marl rocks, especially clay minerals are effective factors on engineering geology properties of these rocks

---

Tunneling in complex geological and geotechnical conditions is often inevitable, especially in urban areas. The stability analysis and the assessment of ground surface settlement of a shield tunneling are of major importance in real shield tunneling projects. The objective of this research is to determine the collapse pressure of a shallow circular tunnel driven by a Tunnel Boring Machine (TBM) of the Earth Pressure Balance (EPB) type.  In this study, analytical methods and three-dimensional numerical modeling with ABAQUS software were implemented to examine the effect of face pressure on the behavior of the tunnel. The parameters were calculated using data from Karaj subway-line 2 as a case study. The analytical method used in this study is Leca-Dormiex which is based on limit analysis theory.  The method is based on a translational multiblock failure mechanism.  Also, elastic and Mohr-Coulomb constitutive model have been used for soil behavior. The results of analytical method and numerical modeling were then compared. Based on the obtained results, face pressure assessed from the analytical method of Leca-Dormiex (upper bound) is the minimum pressure that can be implemented on the face tunnel. It also indicates that with implementation of suggested pressure of analytical method, Karaj subway face tunnel is stable and consequently execution of pre-consolidation methods in this section of the tunnel does not seem to be necessary

---

A slope overlooking conveyor-belt system in Sungun copper mine complex has been downfall in 2006 and the buildings located on the upper part of the slope has been moved and destructed. Since the conveyor-belt system is an important part of the production process that transports excavated material from original stock to the rock-crusher equipment and to have continuous and firm production in the mining process, this slope must be stable during exploitation period safely. For this purpose, in this paper, first the structural and engineering geology of the area was studied and then the stability risk analysis is performed on the slope. According to the results of the stability analyses, the slope may be unstable against slip and probable instability may lead to damage or destroy conveyor-belt and its tunnel. Therefore, considering technical and cost conditions, slope geometry modification method with incorporation of the other methods are suggested to stabilization of the part of slope above conveyer belt. In addition, in the part of slope under conveyor-belt it is suggested to use other slope stabilization methods

---

Determining the precise shear strength parameters of the fine grained soils is always a difficult task. In order to conduct the shear strength tests and determine the mechanical parameters of the soil, achieving an untreated high quality sample is a problem with a high degree of importance. Therefore, during the recent decades many researchers have attempted to provide relations between strength parameters and soil physical characteristics in a specific structure and so to provide the possibility of estimating the strength parameters based on these characteristics. The aim of this research is to estimate the shear strength parameters of a wide region of fine grained alluvial soil located in southern Tehran, Iran. In this regard, the geotechnical data including physical and shear strength parameters of 294 boreholes were firstly collected from the site. Then, the obtained data were statistically and independently analyzed. Based on the results of analyzes, the soil geotechnical parameters were presented for various depths with an acceptable level of reliability. Moreover, they were considered as a basis for providing a nonlinear regression model to estimate the soil shear strength parameters and based on the index physical characteristics of the fine grained soil (water content and plasticity index). The developed model is capable to predict the soil drained shear strength parameters and also other similar soil properties with a very good accuracy

---

Comprehensive laboratory tests were performed to assess fatigue behavior of Alvand monzogranite rock subjected to uniaxial cyclic loading. A series of static loading tests was done to obtain the required data for the fatigue tests. Three maximum load levels (85, 90, 95% uniaxial compressive strength (&sigmac)) at amplitudes 70% were used with 1Hz cyclic loading frequency. The results indicated that maximum stress level significantly influenced fatigue behavior of this rock. It was found that fatigue life decreases in a power function with increasing maximum stress level. Accumulative fatigue damage process shows three stages of behavior including crack initiation phase, uniform velocity phase and acceleration phase. Fatigue damage process were analyzed according to axial and lateral maximum and minimum strain, tangent and second modulus, toughness and hysteresis energy in both loading and unloading conditions. Among these parameters, lateral strain, axial strain and second modulus show the best three-stage fatigue damage behavior. Also, it should be noted that most of the cracks generated in parallel to loading direction and lateral strain are affected by more than axial strain.  

---

This paper presented the feasibility of developing and using artificial neural networks (ANNs) for modeling the monotonic large scale triaxial tests over angular, rounded rockfill and materials contained various percentages of fines as a construction material in some dams in Iran. The deviator stress/excess pore water pressure versus axial strain behaviors were firstly simulated by employing the ANNs. Reasonable agreements between the simulation results and the tests results were observed, indicating that the ANN is capable of capturing the behavior of gravely materials. The database used for development of the models comprises a series of 52 rows of pattern of strain-controlled triaxial tests for different conditions. A feed forward model using multi-layer perceptron (MLP), for predicting undrained behavior of gravely soils was developed in MATLAB environment and the optimal ANN architecture (hidden nodes, transfer functions and training) is obtained by a trial-and-error approach in accordance to error indexes and real data. The results indicate that the ANNs models are able to accurately predict the behavior of gravely soil in CU monotonic condition. Then, the ability of ANNs to prediction of the maximum internal friction angle, maximum and residual deviator stresses and the excess pore water pressures at the corresponding strain level were investigated. Meanwhile, the artificial neural network generalization capability was also used to check the effects of items not tested, such as density and percentage smaller of 0.2 mm.