Summary In this paper, the capability of foundation and support for the Sardasht dam is investigated. Finally, according to the results of numerical modeling in UDEC software, the diameter and distance of grout injection boreholes and dimensions and angle of seal curtain of the dam foundation dam have been suggested. Introduction The injection is a process whereby a cement slurry is pushed into rock formations through a borehole, thereby reducing the permeability and deformation of the rock mass and increasing its resistance. The rocks are almost impermeable and rock mass permeability is often a function of discontinuity systems. Due to the different and unpredictable behavior of rock masses, there is no specific law for determining the distance of injection holes and generally relies on the experience and judgment of the design engineer when deciding on the borehole distance. So, it is proposed to use numerical methods in predicting the radii of injection for grouting material and also determining the ideal spacing between adjacent holes. As the main results of this study, the optimum pattern for drilling sealing systems for different locations of the Sardasht dam was determined and compared to the empirical models using the discrete element method in UDEC. The optimum deviation angle of the holes was investigated, too. Methodology and Approaches The Sardasht dam is a trench with a clay core with a height of about 106 meters and a length of 280 meters. The total embankment volume of the dam body is estimated to be about 3 million cubic meters and the volume of clay core is about 516000 cubic meters. The water diversion system consists of two tunnel strings with an inner diameter of 7m and lengths of 627m and 682m in the right support and its height is about 46m. The right tunnel is used as the lower evacuator during the operation period. In order to investigate the in-situ condition of rock mass in Sardasht Dam area, rock mechanical parameters including rock mass quality index (RQD), specific gravity, uniaxial compressive strength, and geometry and resistive properties of discontinuities have been determined and measured. Then, the quality of grout injection in walls and foundation of the Sardasht dam was modeled, using numerical modeling in UDEC discrete element software. Results and Conclusions The results of this study show that the appropriate borehole spacing for the walls and the foundation should be taken as 3m and 5m, respectively. Also, the results obtained from the numerical modeling of the optimum injection pressure in the construction area of the Sardasht dam were determined for different depths. Based on the numerical modeling results in order to minimize water leakage from the Sardasht dam foundation, the optimum angle of curtain installation should be 17 degrees.

From a practical application of explosives point of view, a successful blasting operation has a high significance. Typical applications of blasting are in the construction of suiface and underground structures for mining and civil purposes. In these applications, successful blasting results in less damage, which may lower support costs, lower dilution and produce a uniform fragmentation. The explosive detonation process creates a pressure front that propagates a stress wave into the surrounding rock mass at a high speed. The stress wave can induce varying degrees of damage, depending on rock strength and physical properties, to the excavated area.This paper presents a summary of a research work that was conducted to investigate the propagation of explosive-induced stress waves in hard rock media and the mechanism of rock damage and fracturing due to the wave action. The primary objective of this work was to numerically simulate the experimental study of blast-induced rock fracturing conducted within Canadian mines. The UDEC (Universal Distinct Element Code) software was used to simulate the conducted blasting experiments. A fairly good agreement was achieved between experimental findings and the results obtained from the conducted numerical analysis.

Summary: This study has been performed with the aim of investigation of dynamic loading effect on permeability of rock mass. The method is 2D numerical modeling that because of discontinuous nature of rock mass and also existence of fracture networks in it, the modeling has been carried out by Discrete Fracture Network-Discrete Element Method (DFN-DEM) conflation approach. Results show that dynamic loading changed the transmissivity of fractures and consequently increased the permeability of fractured rock mass.Introduction: Dynamic loading is a phenomenon that may be applied to rock mass in nature and even leads to changes in some of its geo-mechanical properties such as permeability. The variation in the amount of fluid flow from which the predicted value in a sensitive project such as underground power stations, hydrocarbon fluid flow in its reservoirs and repositories of buried of nuclear waste can cause damages and demolitions. Hence, investigation of dynamic loading effects on the permeability of rock mass is important. In previous studies, some research has been accomplished in the field of rock mass hydromechanics and interaction between static stress and fluid flow in rock mass. However, the lack of evaluation of stress form (static or dynamic) on permeability of rock mass has been felt.Methodology and Approaches: In this study hydro-mechanical numerical modeling has been carried out under static and dynamic stress conditions. All of geometrical and mechanical properties of the models have been for Sellafield site in Cambria, England. As previously mentioned, modeling has been performed by DFN-DEM conflation approach using UDEC. In order to realize results of the method, data from a real earthquake have been utilized as a dynamic boundary conditions. Modeling in this study has been conducted in two groups. Group 1 contains models which have been placed under fluid flow without dynamic loading (in static conditions). In the group 2, the same models have been put under dynamic loading and then under fluid flow conditions.Results and Conclusions: The results show that in contrary with the previous consideration, at least dynamic loading changes the transmissivity of fractures and therefore violates the permeability of fractured rock masses. Despite the fact that in our case study, fracture stiffness is relatively high, calculated permeability of rock mass is greater by 26% at dynamic loading compared with the static loading condition. The major reason is that dynamic loading has caused successive moving the blocks and possible changes in their positions relative to the previous state.