Journal of Engineering Geology

Evaluation of geomechanical characteristics of Asmary limestone in Khersan dam sites

R Ajalloeian

Abstract
(Paper pages 1059-1076)
Physical and mechanical properties of intact rocks are very important in civil engineering works that interact with rock such as underground structures, dams,foundations on rock, and rock slopes. Therefore geomechanical parameters such as compression strength and deformation modulus of rock can have fundamental importance in the different stages of design. Determination of these parameters is time consuming and costly. Since Asmary formation has broad outcrop in the west and southwest of Iran and many large projects are located in this formation, therefore it is a requirement to accomplish the present research. This paper is dealing to analyzing data from laboratory of two major projects of the Khersan 1 and 2 dam sites. In this regard, the physical, mechanical, dynamic and durability properties of intact rock and geology controlling agents of these changes has been evaluated and analyzed. Finally, new experimental relations between different parameters have been presented.

Introduce of new equations for calculation of joint compressive strength (JCS) and elasticity modulus in hard rocks, using Schmidt Hammer results

Schmidt hammer is used for calculation of joint compressive strength and elasticity modulus of rocks. Today, application of Schmidt hammer is a common method in evaluation of properties of rocks. This method is quick, inexpensive and non-destructive which are benefits of this method. In this regard, different experimental equations proposed by Barton & Choubey (1977), Deere (1960), Keadbinski (1980), Aufmuth (1973) and ISRM (1981) can be employed in order to calculate the Joint Compressive Strength (JCS) of rocks. Due to the importance of this research, new experimental equations are introduced. Using this equations show a very good results in comparison with the results of other researchers. It should be noted that this equations are achieved from 827 records of Schmidt Hammer results from different types of hard rocks such as granite, diorite and hornfels from the Ganjnameh-Shahrestaneh road in Hamedan province, west of Iran.

Investigation of rock fall mechanism and risk mapping of Yadak village area in north of Khorasan Razavi

Rock fall hazard assessment is a fundamental land-use planning tool in high mountain area, where human settlements progressively develop across side valley areas, using the worth of potential losses and the restoration costs. The aim of this paper is to evaluate the potential of rock falls along the north east of the Yadak village. This village is located in the Khorasan-Razavi province near the Ghochan city in the northeast of Iran. The existence of the Tirgan limestones with abundant joints and fractures in the north part of the Yadak village causes instability such as rock falls that provide many problems for the residents. Many factors such as rock type, slope morphology, drainage pattern and the seismic activity are considered in this research as affecting factors. For joints investigation in the study area, the dip and dip direction of more than 180 discontinuities measured and analyzed using dips. Since most of the slope instability along the north part of the Yadak village are the rock falls type. Rocfall software was used to investigate the rock fall mechanism. Finally, the rock fall hazard zonation map is prepared using GIS program.

A Study on the Geotechnical Features of South Karaj Alluvium

zohreh safipoor rashvanlu

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.

Development of a simplified image processing technique for determining crack intensity factor of compacted clayey soils

Mahdi Jalili Ghazizade

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.

Estimating mechanical properties of limestone from petrophysical data

Abstract
(Paper pages 1159-1178)
Young’s modulus measured as the slope of the stress-strain curve under static loading conditions (Es) in the lab is one of the most essential parameters for reservoir geomechanical modeling. However, information on the value of Es along the well length is often discontinuous and limited to cross well with the core. On the other hand, well log data for wave velocities Vp and Vs are often available for most hydrocarbon reservoirs. Hence, well-known equations are needed to calculate static Young’s modulus based on the compressional and shear wave velocities (Vp and Vs) that is dynamic Young’s modulus (Ed). Unfortunately, because of porosity and micro cracks in rock texture, Es and Ed are not equal. Therefore, correlation between static and dynamic parameters could result in a continuous and more reliable knowledge on the elastic parameters along the well length. In this research, laboratory experiments were carried out on limestone rock core specimens of Sarvak formation obtained from an oil well in the South West of Iran. Empirical relations were suggested to estimate UCS and static Young’s modulus from compressional wave velocity (Vp) and dynamic Young’s modulus. These empirical relations are prerequisite for continuous wellbore stability analysis in oil and gas well drilling

Soil classification based on Iranian Standard No. 2800, 1997 UBC, 2006 IBC and 2004 Eurocode 8. A Case study: Piroozi Street (Tehran’s municipality-13)

Abstract (Paper pages 1179-1194) The site under study is located in the south of municipality-13, east of Tehran. Numerous building construction activities and large investment have been done in this area. Hence, it is important to have a good knowledge of the site characteristics. Soil classification is a very effective tool for optimum engineering construction which may reduce the future earthquake hazards. Building codes such as standard No. 2800, UBC, IBC and Eurocode 8 were used for soil classification. Seismic and geotechnical data were collected. Based on the considered Building codes the average seismic velocity and SPT values were estimated. It was concluded that Piroozi Street can be grouped into II, SC, C and B classes.