نشریه زمین شناسی مهندسی ایران
سال دهم شماره 1 (بهار و تابستان 1396)

In nature, rocks contain non persistent joints and in rock slope stability analyses it is assumed that discontinuity is persistent, while stress intensity is centralized attips of non-persistent joints and this stress intensity affects the size and orientation of joint growth in rock and also stability of structures created in it such as rock slope. Fracture mechanics is a science that discusses the probability of joints growth and also fracture propagation path. The development of this science provides the possibility of using actual non persistent joints modeling in rock slope stability as well as controlling mechanical behavior of discontinuities especially in crack tips. By creating rock slopes and changing the matrix of regional stress, intensity of stress occurs in joints tips. If this stress overcomes strength parameters of the joint, it will grow and joint propagation will result. One type of failure that occurs in rocky environments due to crack propagation is toppling whose analysis is one of the most difficult problems in aeromechanics. The aim of this study is to model joint propagation by using the principles of rock fracture mechanics, growth and publication ofnon -persistent and random joints in rock slope with potential of toppling failure. An acceptable numerical method for joint propagation modeling that is boundary element method as displacement discontinuity method (DDM) was selected. As a case study tectonic block IV-2 of Choghart open pit mine was selected and3D geometrical model by random disk method by 3DGMMathematica program was simulated and also 2D cross section was prepared. The amount and direction of joint propagation were calculated by applying boundary conditions, in-situ stresses and stiffness matrix. The mechanical model was created according to geomechanical characteristics reported in stability analysis of this wall. Length of linear elements in joints was considered 3m and propagation step applied was 0.2 over the joint length and the model was run typically in four stages of crack growth. Obtained geometrical model contains early and propagation joints can be used in softwares that geometrical model of joints is essential I analysis but the propagation of joint is not available. So the program code can be used as a complementary method for analysis method as key-groups method and distinct element method (UDEC) to analyze the jointed rock mass

The main objective of this paper is to identify suitable site to construction underground dam in Qare-Booteh Flood Plain at South West of Zanjan Province. The groundwater level of the floodplain is reduced in recent years. Underground dam construction could compensate some part of the ground water scarcity. Therefor, the area has been investigated to find suitable site for underground dam construction and 13 potential sites have been identified in preliminary surveys. Due to the effect of several factors to determine the best site, the most significant factors have been recognized. These factors include; geological units,faults, type of the drainage, water quality, depth of the bedrock and reservoir volume. Using hierarchical analysis, dual comparison between the main criteria and sub-criteria has been carried out and the coefficient effect of the each factorhas been calculated. In order to compare the theresults, usual weighting method is used to prioritize the options. The comparison shows the consistency of appropriate prioritize options result by two different methods. However, it seems that the result of AHP method is more reliable due to pair judgment of the factors

Lightweight aggregates are being used to reduce weight for making light products such as light concrete, mortar and lined, thermal and acoustic insulation, mortar and lined, bitumen productsand agricultural soil. Shaly formation is abundant in different structural zones of Iran, on the other hand, clay resources needed for producing lightweight aggregates are valuable to environmentally and agriculturaly, and hence shales are good alternative materials for production of lightweight materials. In this paper, chemical analysis on shaley and marly formation in Fars province was carried out. Then, according to these studiesBeckat argillous and Noorabad shale were recognized suitable for production of lightweight materials. In next step some physical, chemical and mechanical properties of lightweight aggregate were determined and compared with lightweight aggregates which were produced in Iran. Results showed that manufactured expanded lightweight aggregates have lower specific gravity and higher water absorption, pressure and impact value than Lica and Liapor. From aspects of grain size analysis and pH, all three types of lightweight aggregates were similar. According to the results,produced expanded shale is lighter than other lightweight aggregates which are produced in Iran. But it has lower strength than Leca and Liapor, so it can be used as bacfill, construction of insulation and lightweight aggregate for discriminant and non-load-bearing walls

Various Codes to evaluate sources for use in hydraulic structures such as Rip rap dams, offshore structures such as breakwaters and coastal protection is provided. Although there are differences between the codes, but to an assessment of the aggregate According to the codes, various tests required is often time-consuming, costly and administratively would be difficult sometimes. One method is fast, easy and low cost, the Petrographic Number method of thin sections is due to review the proposals are to impart quality stone materials. In this article, we discuss the application of this method in some of the country's aggregate resources. 33 samples of limestone materials used in resources of marine protection structures and dams on the south coast of Iran have been collected. Results have shown that a link between the Petrographic Number with regulations and testing results.

The block-flexural toppling due to the involving the multiple failures mechanisms (e.g. slip-rotation-bending and shear) has always been considered and analysed only in the form of kinematic approaches and its instabilised mechanism has been much underestimated. In this paper, we have tried to evaluate the block-flexural toppling failure mechanism by application of distinct element method (DEM) by UDEC software which is considered as the most complex instability type in the discontinuous rock slopes assessment. For this purpose, a discontinuous rock slope which is located in Assalouyeh - Kangan (in South Pars Special Zone) freeway side is considered as a case study. This discontinuous marly limestone slope which is belonged to Aghajari formation is the main cause of instability and slip in freeway. According to the modelling results, the numerical methods capable to successfully simulated of progressive slip scenario the final critical sliding surface is estimated for slope under the block-flexural toppling mechanism. Also, the multiple failures mechanisms are been intuitively recognized and fully identified

In this paper, the effect of confining pressure directionality on the rock fragmentation has been investigated using PFC2D. For this purpose five different directionality was used, i.e. 0°, 30°, 45°,60° and 90°. Tensile strength of all models is 2.1 MPa. These models are under confining pressure of 5%, 10% and 15% of crack initiation stress. Totally 15 model were simulated. Disc cutters are U shape and its spacing was fixed (1a: a, is cutter width). The result shows that the optimum directionality for confining pressure is when its angularity is 0°.

Rock powder, aggregate, a small amount of cement or resin and other chemicals are used for producing artificial stone.In this research, limestone aggregates (in the size 0.075 of 19 mm), rock powder and white cement were mixed and wetted and then, they were compressed under three physical processes including vibration, vacuum and pressure in a cubic mold. The aim of this study is investigating the effect of pressure and vacuum on the improvement of physical Characteristics of produced artifitial stone. As well as comparing the characteristics of artificial stone which made with two natural stone, including marble stone (primary rock in the production of aggregate) and travertine (porous and light weight stone). The results showed that the artificial stones have similar engineering characteristics to travertine stone. Therefore, a mixture of cement-aggregates can be used to make molded artificial rocks with acceptable engineering characteristics.

The water tunnel at Mashooreh Dam has been constructed to supply the required water for the hydropower plant at the dam. Mangeni and Khorram-Ababd anticlines are among the most primary geological structures through which the tunnel has been built. In this research, three methods were used to propose a support system for the tunnel: empirical, analytical, and numerical methods. In the empirical method, RMR and Q techniques were employed. RocSupport Software was utilized to analyze stability of the tunnel analytically. In the numerical analysis, Phase2 Software (based on finite-element method (FEM)) was used. Results of the numerical analysis indicated total, horizontal, and vertical displacements of 11.4, 6.3, and 11.4 cm, respectively, when no support was installed. However, upon installing the proposed support, total, horizontal, and vertical displacements decreased by 4.7, 2.8, and 7.4 cm, respectively. Following the installation of the support system, safety factor enhanced to 2.21, indicating stability of the tunnel. The results of the three experimental, analytical and numerical methods of the similar maintenance system are presented.