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Wang T.,Wuhan University | Wang T.,State Key Laboratory of Water Resource and Hydropower Engineering Science | Wang T.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | Zhou Y.,Wuhan University | And 3 more authors.
Minerals Engineering | Year: 2011

Phosphogypsum tailings are piled up to form a phosphogypsum tailings pond. In the design and operation stages of a tailings project, the stability of the tailings pond, the control capacity for flood, and the reliability of the drainage and safety monitoring facilities should be fully evaluated. Key contents of the safety assessment are analyzed in view of the new Xiangyun phosphogypsum tailings pond, which is currently in the design stage. Flood routing calculation results show that the pond cannot meet the requirements of the China National Standards Safety Code in the condition of a 500-year flood even if the drainage facilities operate normally. Seepage and static stability of the tailings pond are investigated through numerical and limit equilibrium methods. The results indicate that the sliding stability can meet the requirements along the starter dike profile. Dynamic calculation results show that the liquefied area is at the top of the dam slope and it cannot influence the dam safety. The aspects of safety monitoring design that require attention are also proposed. © 2011 Elsevier Ltd. All rights reserved. Source


Rong G.,Hubei Engineering University | Rong G.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | Peng J.,Hubei Engineering University | Wang X.,Hubei Engineering University | And 2 more authors.
Disaster Advances | Year: 2013

The Jinping-I hydropower station sits in the west of Great River Bend of Yalongjiang River. Deep cracks are well developed in the slope of the hydropower station. This study is focused on formation mechanism of deep cracks in the left bank slope of Jinping-I hydropower station. Characteristics of in-situ stress in the dam site and the development law of deep cracks in the slope of Jinping-I hydropower station are analyzed. Finally, development of the river valley of Jinping-I hydropower station is simulated by adopting three dimensional distinct element code (3DEC) and variation of stress field as well as distribution of deformation and unloading in different stages of the river valley erosion are discussed. Based on the results and basic law of deformation and in-situ stress of the slope valley, it can be indicated that deep cracks developed in the left bank slope of Jinping-I hydropower station resulting from failure of rock masses which are controlled by the original dominated tectonic fractures. The failure is caused by the regional concentrated stress at the elevation of (EL.) 1700~1850 m in the slope during the process of valley erosion leaded by fast crust uplift and quick river erosion. Source


Wang T.,Wuhan University | Wang T.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | Wu H.,Wuhan University | Li Y.,Wuhan University | And 6 more authors.
Computers and Geotechnics | Year: 2013

The stability of the slope around a flood discharge tunnel is influenced by the space topography, the geological structure, the seepage of the flood discharge tunnel, the rainfall and so on, which introduce complexity and uncertainty to the problem of slope engineering. For slope stability analysis at the outlet of a flood discharge tunnel affected by high interior hydraulic pressure, the inner water exosmosis (IWE) phenomenon will become obvious, the rock's mechanical properties will be changed, and the seepage effects of the flood discharge tunnel should be focused on. In this paper, a complicated three-dimensional (3D) numerical simulation and safety assessment of the slope around the flood discharge tunnel at Yangqu hydropower station is implemented in FLAC3D, and 3D slide arcs of good shape are obtained. When calculating the safety coefficient of slopes, the Shear Strength Reduction Technique (SSRT) is adopted, and a factor of safety (FOS) is then found. It is found that the FOS of the natural slope is 1.43 in its original condition, and in this case, the slope is in a stable state. The safety factor of the slope is 1.30 after the slope excavation without considering IWE. Under the condition of normal seepage from inside the tunnel to the outside, the safety factor is 1.29. For investigating the influence of IWE on the slope stability, we design three types of scenarios - minimal seepage, normal seepage and serious seepage - for the fluid-solid coupling calculation. Under the serious seepage condition, the safety factor of the slope is 1.26, and it is in a critical failure state. It should be pointed out that uncertainties in input parameters are not researched in this paper. There is not big difference among safety factors under different scenarios mainly because the maximum of inner water head of the flood discharge tunnel is only about 80m. It still can be found that seepage action has an effect on the stability of the whole slope from calculation results. The stress concentrated region (SCR) near the surrounding rock grows from inside to outside as the seepage intensity increases. The surrounding rock will experience more water pressure and seepage pressure, and, at the same time, the area of the plastic zone grows. Suitable treatments and suggestions are discussed to eliminate the adverse effects of IWE. The research results in this paper can provide a reference for construction, reinforcement and drainage design of the slope in similar hydropower slope engineering scenarios. © 2013 Elsevier Ltd. Source


Guan R.,Hubei Engineering University | Guan R.,Lawrence Berkeley National Laboratory | Jun P.,Hubei Engineering University | Jun P.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | And 2 more authors.
Disaster Advances | Year: 2013

Cracks propagate under compression of rocks and these cracks are mainly tensile. Shear band can be formed as the result of interaction of tensile cracks and shear failure finally occurs with propagation and interaction of cracks in the rock. It has been found that progressive failure process of rocks is affected by mineralogical composition, grain size, texture and foliation etc. External factors such as the confinement and excavation disturbance also have great effect on progressive failure process of rocks. The influence of water pressure on progressive failure process of sandstone was studied based on the experiment. It was indicated that with increase of water pressure at both ends of the rock sample, crack initiation stress σci had a tendency to increase and crack damage stress σcd and peak strength σf decreased gradually. With increase of the confinement, stress thresholds during progressive failure process of sandstone decreased gradually. Source


Li D.-Q.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Li D.-Q.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | Li D.-Q.,Wuhan University | Tang X.-S.,State Key Laboratory of Water Resources and Hydropower Engineering Science | And 5 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

A new global optimization reliability method, knowledge-based clustered partitioning method (KCP) for reliability problems involving correlated non-normal random variables, is proposed. Firstly, the isoprobabilistic transformation is adopted to transform the non-normal variables into the standard normal ones. Secondly, the Nataf transformation is used to transform the correlated non-normal random variables into the independent standard normal ones, which facilitate the sampling of the correlated non-normal random variables and reliability computation using the knowledge-based clustered partitioning method. To remove the limitations of the KCP with the binary step length and the KCP with equal step length, the KCP with changing step length is proposed, and the flowchart of reliability analysis using the KCP with changing step length is provided. Furthermore, a C-language based computer program is developed to carry out the reliability computations using the proposed KCP method. Finally, an example of reliability analysis for rock slope stability with plane failure is presented to demonstrate the validity and capability of the proposed method. The results indicate that the proposed knowledge-based clustered partitioning method can evaluate the reliability of rock slope stability involving correlated random variables accurately and efficiently. Furthermore, the global optimization solutions can be determined using the proposed KCP method. The proposed KCP method can result in the same accuracy as the traditional Monte Carlo simulations, and its efficiency is significantly higher than that of the traditional Monte Carlo simulations. More importantly, the KCP with changing step length can ensure an optimal balance between the accuracy and the efficiency of reliability computations. Source

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