نشریه زمین شناسی مهندسی ایران
سال دهم شماره 3 (پاییز و زمستان 1396)

The science of earthquake prediction has not yet reached its desired level of development. It has not yet led to a successful prediction of an earthquake based on physical principles. Therefore, the prediction of the occurrence of an earthquake has always been an interest for researchers. Three parameters of earthquakesincluding: time, location and magnitude, are the most important uncertainties in earthquake prediction. Uncertainties of earthquakes have the fundamental role in assessment of reliability of structures. In reality, the mechanism of earthquakes makes predicting them more difficult. Earthquake prediction will have a special validity if random variables consider. Therefore, nowadays statistical hypothesis methode are used to determine the probability of an earthquake. There are many studies in prediction of earthquake parameters, but there is not any particular research in the probabilistic earthquake hazard zonation. Kerman province has experienced destructive earthquakes such as Bam, Golbaf and Zarand as the one of the most seismic regions of Iran. In this study, the probability of future earthquakes location with the magnitude greater than 4.5 Richter has been predicted in Kerman by using artificial neural networks and statistical analysis. The most probable event of earthquake has been predicted 38.6% in south of Kerman.

Large underground caverns are used for a variety of purposes in rock engineering. These include caverns housing turbines, electrical generators and transformers in hydroelectric projects, caverns for storing liquid or gaseous fuels, underground warehouses and underground sports facilities. Rock-anchoring tendons is one of the most effective supporting system to control rock mass failure in underground excavations. However, in the deep underground excavations failure of the tendons has been frequently reported. The purpose of this study is evaluation of the effect of in-situ stress on the mechanical behavior of rock anchoring tendons. For this aim, Raghun underground power cavern located in Tajikistan's Dushanbe was studied as case study. An accurate 2D model is prepared by FLAC 2D V. 7.0 and the sidewall convergence of cavern is compared with the monitoring data recorded from 1989 to 2015. In the next, effect of in-situ stress on the mechanical behavior of tendons in cavern’s wall is considered and it is found that with increasing the cavern depth, the effect of pre-stress on the reduction of wall deformation decreases.

The relation between Soil compression degree and the permeability changes during static compression process is one of the important factors for understanding hydro mechanical soil behavior. In this research such relationship has been closely studied. Three soil samples have been selected from loess soil (wind deposits) that extended widely in Golestan province, north eastern Iran. In first step, a test apparatus must be design to measure the soil compression degree and permeability value simultaneously. The designed apparatus is able to set high porosity soil sample in a test cell, measurement static compression force, compression degree and the value of permeability at different stages of soil compression process. In addition, soil structure can be observed during the test through a camera attached to the test chamber. The results show that soil type and primary structure affect soil compression behavior. Result of Permeability tests of loess soil shows that there is logarithmic relation between void ratio and permeability and its general form of experimental relation is proposed in this research.

The durability of stone against environmental degradation factors is one of the most important issues related to stone selection for use in engineering structures, in particular stone stones. The crystallization of soluble salts is one of the most important weathering factors in nature, which can affect the mechanical properties of rock (such as uniaxial compressive strength and Brazilian tensile strength) and, over time, can decay and reduce its durability. In this research, a physico-mechanical parameter has been introduced that can assess the mechanical properties of rocks and thus their durability against salt weathering with accurate accuracy. To achieve the research objectives, 15 travertine samples were selected from different mines in Iran. Travertine samples were prepared to determine the physical properties (water absorption, mean pore diameter) and mechanical properties (uniaxial compressive strength and Brazilian tensile strength). Then, the physico-mechanical parameter was calculated, based on the combination of water absorption, mean diameter of the pores and mechanical properties. By performing bivariate regression analysis, the relationship between physico-mechanical parameter with uniaxial compressive strength and Brazilian tensile strength after the salt weather test was investigated and the most suitable relationships for estimating the durability of the samples using a physico-mechanical parameter against weathering is presented. The results show the correct accuracy of the physico-mechanical parameter for estimating the durability of the studied samples. As a result, the Physico-Mechanical Parameter avoids performing a salt crystallization test, which is time-consuming and expensive.
The durability of stone against environmental degradation factors is one of the most important issues related to stone selection for use in engineering structures, in particular stone stones. The crystallization of soluble salts is one of the most important weathering factors in nature, which can affect the mechanical properties of rock (such as uniaxial compressive strength and Brazilian tensile strength) and, over time, can decay and reduce its durability. In this research, a physico-mechanical parameter has been introduced that can assess the mechanical properties of rocks and thus their durability against salt weathering with accurate accuracy. To achieve the research objectives, 15 travertine samples were selected from different mines in Iran. Travertine samples were prepared to determine the physical properties (water absorption, mean pore diameter) and mechanical properties (uniaxial compressive strength and Brazilian tensile strength). Then, the physico-mechanical parameter was calculated, based on the combination of water absorption, mean diameter of the pores and mechanical properties. By performing bivariate regression analysis, the relationship between physico-mechanical parameter with uniaxial compressive strength and Brazilian tensile strength after the salt weather test was investigated and the most suitable relationships for estimating the durability of the samples using a physico-mechanical parameter against weathering is presented. The results show the correct accuracy of the physico-mechanical parameter for estimating the durability of the studied samples. As a result, the Physico-Mechanical Parameter avoids performing a salt crystallization test, which is time-consuming and expensive

Ballast shear interlocking is phenomenon that occurs between adjacent ballast masses under sleepers due to axial loading. This phenomenon is caused when three factors: 1) large thickness of the ballast layer, 2) large stress distribution angle at ballast mass of under sleeper, 3) small sleeper spacing are available at ballasted track. Thus, despite these three factors together and based on the assumption of transfer load from sleeper into ballast mass in accordance with a stress distribution pyramid, caused an overlap between two adjacent pyramids that this intersection would mobilize shear stiffness and shear damping in addition to stiffness and damping ballast layer in the vertical direction. This stiffness and damping is called the shear coupling. Considering the fact that so far, few studies have investigated about these parameters, but the method for calculating them is not provided in the technical literature. Therefore, in this research by developing a laboratory method in order to determine the ballast shear stiffness parameter and shear strength, shear tests of ballast in the vertical direction in the locking zone under static overheads 200, 300 and 400 kg in the relative density is 70.95% done and the effect of relative densities of 40, 70 and 94.44 percent on the shearing of the ballast is investigated. For this purpose, a device for shear of ballast in Railway Superstructure Laboratory of the railway engineering school was designed and built. Finally, based on the results and the integrate them, in order to use the results a mathematical relationship for ballast shear stiffness parameter has been determined which includes the axial load and vehicle speed and high density relative of the ballast.

In orther to the stability analysis of Golgohar No.1 mine waste dump, cohesion and friction angle of materials is necessary to determine. Because the determination of these properties requires the use of in-situ shear test and large scale triaxial apparatus and expensive methods, hence, back-analysis method as a low-cost method can be used to determine the shear strength properties. Due to the tensile cracks are observed on the surface of the waste dump, so it can be considered safety factor approximately equal to unit and using the back-analysis method the shear strength parameters can be estimated. In this paper, the analytical and numerical methods by FLAC/SLOPE and Slide software and charts provided by Hoek and Bray have been used to determine the shear strength parameters of materials and their results were compared with each other. This analysis shows cohesion and internal friction angle for materials using analytical and numerical methods and Hoek-Bray charts obtained respectively 19.2 kPa ,24° and 21.4 kPa, 24° and 21 kPa, 24°. With the development of open pit mine and more mineral extraction, the amount of waste collected in the same proportion will increase. This increase is caused larger waste dump, that will threaten its stability on the one hand and the other hand because of the proximity to the mine walls can affect the stability of the wall. So with according to continuation of the waste dumping and transport costs, slope stability and height stable and optimal distance from the south wall of the mine must be considered. In this study, using numerical methods in order to achieve stable safety factor of 1.2 for the waste dump with change the height and angle of slope of the bench, the stable height and angle of slope has been obtained. Also, in order to determine the safe and optimal distance of waste dump from the wall of the mine the analytical methods used and the effect of distance on the safety factor of wall is investigated. The results show that at distances of less than 150 meters from the wall, the safety factor of wall is more reduced and this distance can be considered as a safe distance.