نشریه زمین شناسی مهندسی ایران
سال شانزدهم شماره 2 (تابستان 1402)

In this research, 13 different quarry rubble mines in Kurdistan province are selected as the case study for geotechnical stability monitoring. For this purpose, felid surveys are done and lithological, structural and geometrical properties of mines bench evaluated and recorded. Also, representative block samples are collected form working face of these mines to perform the experimental studies. Then, coring operation is performed over the above-mentioned blocks and cylindrical cores are provided for conducting the unconfined compressive strength and point load testes and preparing input data for slope stability analysis. Finally, the geometrical characteristics, boundary conditions and geo-mechanical properties of mines are designed using AutoCAD software. Then, the actual conditions of the available layers are simulated using Slide software and slope stability analyses are conducted. According to the numerical modeling results, the safety factor of Boghdeh Kkandi mine bench is obtained equal to 0.784. This proved that its bench is unstable and unsafe and slope decreasing and modification of the mine blasting pattern are required immediately. Also, the benches of Halozhan, Khoshkin, Sernjyaneh Olya 2, Babariz 3, Babariz 4, Sman, Kani Pahn and Abbas Abad are stable and the probability of their benches failure and collapse is low in the short term condition. At last, the benches of Zekkryan, Darrebagh, Bilo Arandan and Askaran mines are stable in the current state but they may reach the failure/collapse phase in the near future. Therefore, these mines will need the periodical regular monitoring and control the occurred deformations to ensure the required safety.

In this paper, the determination of equivalent elastic properties of fractured rock masses has been studied using discontinuous numerical method. For this purpose, the discontinuous media of the jointed rock mass with different jointing patterns (including one horizontal joint set, one vertical joint set, two perpendicular horizontal and vertical joint sets, and two non-orthogonal joint sets) were modeled in UDEC software and the induced strain were calculated. Then, the elastic properties of rock mass were calculated by inserting strains obtained from numerical methods into compliance matrixes. In order to verify this procedure, the results of back calculated elastic properties of rock mass from numerical models were compared with those obtained from analytical solutions. Finally, the method of back calculated elastic properties of rock mass from numerical models was applied for confining stress boundary condition (the case without analytical solutions) under different rotation angle of discontinuities and scales. The results of this study show that there is a good consistency between the back calculated elastic properties of rock mass from numerical models and analytical solution; where the relative error is about 4% to 6% for most of the cases. This consistency indicates the accuracy of back calculated elastic properties of rock mass from numerical models and this method can be applied for other cases especially those without analytical solution. Application of this method for rock mass under confining stress (the case without analytical solution) indicates that the elastic properties highly depend to rotation angle.

Green's empirical function method has been used to simulate the strong motion of the Damavand earthquake. One of the conventional methods of simulation to produce strong ground motion is the use of aftershocks and foreshocks of large earthquakes using the empirical Green's function method; As a result, the ground motion simulation algorithm based on Green's empirical function, presented by Hutchings and Wu (1990), has been used to simulate the Damavand earthquake waveform.On 02/18/2019, an earthquake with a magnitude of 5 occurred in Damavand, located in Tehran province. In this study, with the aim of estimating the parameters of the source and the mode of fracture in this earthquake, the empirical Green's function method has been used to simulate the powerful movement of the earth. To simulate the main earthquake, a foreshock with a magnitude of 2.9 near the center of the main earthquake, as well as aftershocks with a magnitude of 3.9 and 4.1 recorded at the Masha and Rodhen accelerometer stations, have been considered as experimental Green's function. The length and width of the fracture in this earthquake are 2 and 3 km, respectively, in the direction of extension and slope. Calculations show that the direction, slope and tilt of the fault that caused the earthquake were 196, 76 and 156.5 degrees, respectively. The focal mechanism of this earthquake is of reverse type with strike-slip component, which is consistent with the mechanism of earthquakes in this area.

The deformation modulus indicates the degree of deformability of the rock mass in response to any loading and unloading, and it is important because it plays a role in the design of most underground structures. Estimation of this parameter on site is usually done with the help of two tests of plate loading and dilatometer, which is associated with spending a lot of money and time. In addition, due to the presence of discontinuities and cracks in the rock mass, laboratory tests on core samples also face errors. Today, to define a relationship between a parameter and its dependent parameters and to build a model to estimate or predict the chosen parameter, a variety of computational intelligence methods are used, and of course, they also provide favorable results. The purpose of this research is to use these types of algorithms in order to create an efficient model for predicting the deformation modulus on a database. In this regard, the performance of three models created by artificial neural network, K-nearest neighbor and random forest methods have been evaluated with the Orange software. The results showed that the artificial neural network model has the best performance and accuracy with RMSE=0.116 and MAE=0.094. Also, the sensitivity analysis of the input parameters shows that the RMR system is considered as an important and effective parameter.

The current study evaluates ordinal logistic regression (OLR) for assessing collapse sensitivity classes of loess soils. Collapse sensitivity (Is) is the critical parameter to predict pseudokarst sinkholes occurrence in Golestan Province in northeastern Iran. A database containing 62 records of soil's physical and mechanical properties is used in this study. By performing oedometer tests, the parameters of collapse coefficient, the time required for 90% settlement (T90%), and collapse sensitivity were determined. To gather this goal, a database was prepared based on experimental datasets, consisting of ten inputs (grain size analysis, porosity, initial water content, precipitation, climate, liquid limit, calcium carbonate, vegetation, and degree of soil saturation) and one output (collapse sensitivity classes). This task is complex due to the difficulty of preparing and carrying out such experiments in a laboratory. Using OLR, the probability of soils being placed in classes with severe, moderately severe, moderately, and slight sensitivity was estimated. This study showed that the OLR method could correctly distinguish more than 70% of different categories. Experimental data obtained from Semnan, Sarakhs, and Mashhad areas, has shown the accuracy of the proposed OLR model.

Energy pile is dual purpose foundation that transfers structural loads and also transforms energy. They act as heat exchanger in addition to transferring loads to underneath earth layers. The change in temperature along energy piles, resulting from their employment in heat exchange operations, causes axial displacements, thermally induced axial stresses and changes in mobilized shaft resistance which may have possible effects on their behavior. To investigate the effects of soils on energy pile, in present study a two dimensional (2D), axisymmetric numerical model for the energy piles has been created using finite element method base on the field test. The main purpose of this study is investigating energy pile response in various soils. This was performed by considering some different hypothetical layers with the bedrock under them and their results which included displacement, strain and stresses induced by thermal load compared with four layered soil experimental data. The results showed that soil properties have important effect on the response of energy pile. Also temperature affects pile reactions. e results showed that soil properties have important effect on the response of energy pile. Also temperature affects pile reactions. Obtained results show that displacements, stresses and strains in layered soils are between the displacements, stresses and strains obtained in homogeneous soil layers. The results show that the soil stiffness increases, the strains decreases

Nowdays, many dams are building in karstic areas, and usually due to the complex hydrogeology of karst areas, the sealing of these dams are more difficult, longer and expensive than other dams, and the possibility of water leakage from them is higher. Therefore, it is necessary to investigate the role of karst development in the dams’ sites. The Abivard dam is an earthen type with a clay core, with a height of 51 m and a lake volume of 43 MCM, near Ilanjogh village. The emergence of downstream springs in calcareousness Kalat formation, after temporary dewatering of Abivard dam, the development of karst due to the outflow of water is considered as the most important problem of the dam. In this article, the development of karst in the area and dam site were investigated by carrying out the geological, structural geology, geotechnical permeability and analysis hierarchy process (AHP) studies. The results show that about 2.4 % of the the Abivard dam area (680 km2) has a high potential of karst development and there is water leakage and water escape from the Kalat formation on the right hand side and in under the dam, but still karst is not well developed. According to the prepared structural-conceptual model for the dam and the location of the dam reservoir relative to the Kalat formation layering slope, which is parallel to the sothern limb of Abivard syncline, there is a possibility of karst development in the dam site.