| The major part of this thesis was a comprehensive slope stability analysis include effect of strength parameters, slope monitoring method and impact of water in mining activates in the case study(Southern slope of Chengmenshan Copper mine). According to the geotechnical study, the mine was classified into 6 zones of engineering geology(I, II, III, IV, V and VI). The engineering data of the six types of rocks were collected from different parts and depths of the early developed pit, because of the weathering process, the contact plane between two kinds of Rocks type has formed soft-weak layers with very low strength which is basically parallel to the dip of slope and threats the stability of slope. field investigations and reports by operators demonstrated that some instability problems might occur in the Southern slope which is situated in zones I and II. The hydrogeology condition was very complicated, mining area is surrounded by lake water, only the south side is land. The geological and hydrogeological exploration data of case study was extensive collected on the basis of quality, using the original pumping test, detailed fine structure understand of the aquifer system, different water permeability and hydraulic conductivity of the layer parameters such as determining the mine aqueous systems. Three-dimensional geological model MODFLOW(The U.S. Geological Survey) based on finite deference method was used, groundwater system model was built, and the model was divided into five layers, based on the aquifer permeability coefficient of each region. After hydrogeological analyzed condition and establishes conceptual model of the mine, then properly forecast the inflow rate of groundwater in the mine, by comparison of the several aspects such as economic, technological, dredge and blocking combination was determined as main plan for prevention and treatment of ground water in mine area. The Southern slope of the mine was divided into six sections(I-0, I-1, I-2, II-0, II-1 and II-2) for slope stability analysis under various conditions which consider the effects of seismic, water and weak layer. Stability analysis performed by Slope/W, Slide as limit equilibrium based software and Phase 2, Slope/W and Sigma/W(Shear Strength Method) as numerically based software. Analysis procedure was cured out in two parts: First, self-weight(condition 1). Second, Sections subjected to seismic, water and weak-layer(condition 2). Slope stability analyses were carried out; results showed that the safety factors of some section are very low. Computed FOS of six sections with different method, shows that the FOS for the six sections is quite different. However, the FOS of first three sections(I-0, I-1 and I-2) was very low which indicated of the critical condition for the three sections, calculations of FOS shows that the weak-layer in sections(I-0, I-1 and I-2) was effected the stability of the Southern slope and failure is likely to take place.Results showed that reinforcement is very important to increase the FOS of these three sections. Two methods were used; First, Pre-grouting by pumping the cement slurry into the sliding surface with high pressure along the slope using a variety of channels to penetrate the landslide body, squeezing out water and then increase the sliding soil shear strength. Second, Pre-stressed anchor reinforcement has been installed in the slope of the three sections to increase the FOS by more than 1.15. Back analysis was done to get the amount of the reinforcement force in every section, Slide and Geostudio software was used to make the calculation.For the strength parameters(rock and soil dilatancy) and its influence on slope stability, it was found that cohesion c and friction angle ? have the largest impact on the stability of slope compared to other parameters, however, most researchers use dilation angel equal to zero or to friction angle in their models. Dilation angle it is not only affect the volume change in geotechnical, but also the safety factor. The study describe two numerical slope stability of homogenous soil with plane strain model, to study the influence of dilation angle through different friction angle(20, 25 and 30), the analysis fixed friction angle with different value of dilation angle, results shows that safety factor increase gradually with increase of dilation angle and dramatically decrease when dilation angle close to friction angle, that mean the high factor of safety when dilation angle equal or close to 0.75 of friction angle(ψ ≈ 0.75 ?), when dilation angle equal to friction angle(ψ=?) get the low factor of safety So it’s very important to conceder which is the accurate value of dilation angle ψ close to the real.The thesis reviews the main role of slope monitoring including descriptions of the applications of monitoring equipment’s for open pit slope. Unexpected failure at mining sites is a major cause of death, serious injuries, economic and production losses. As open pit mines get larger and deeper with its related high risk of failure and consequences, slope monitoring methods become more important. Sub-surface methods and surface methods are common methods that have been applied to monitor stability of slope. Survey monitoring methods which include Total station, global positioning system(GPS) and slope stability radar(SSR) are pointed as the most recent monitoring methods in mining fields. Early detection of failure in mine slope can help implement appropriate monitoring technique and minimize failure effects. Slope monitoring in mining environment basically eliminates the residual risk associated with uncertainty in design and can play leading part of the final design implementation. Accurate monitoring program is a detailed plan of reporting procedures with a list of data collection by Geological engineer at early time, then processing and summarizing the data to present it in simple format that is easy to read and identify problem area quickly. Through analysis of different monitoring methods, it was found that the highest success rate is obtained when a mine site uses multiple monitoring tools to evaluate the movements of slopes. |
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