Time filter

Source Type

Chen J.,National Key Laboratory of Gas Disaster Detecting Preventing and Emergency Controlling | Wang T.,Wuhan University | Wang T.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | Zhou Y.,Wuhan University | And 2 more authors.
International Journal of Coal Geology | Year: 2012

The effective control of gas emissions from longwall faces and gob areas in the coal mining industry in China has become increasingly important. Drilling underground gas drainage holes from a surface is an effective way to release gas. Once a coal seam is extracted, the rock strata above a gob subside and move, after which the gas drainage borehole and casing become damaged due to state changes in the rock. In this paper, we perform a deformation and failure analysis of a surface venthole casing using the numerical simulation method. The numerical investigation is carried out on the casing under compression, tension, and shear conditions. The general factors that affect casing failure are discussed, and basic failure modes are summarized. The experimental casing of the surface venthole at Cheng Zhuang Colliery (CZC) is also analyzed by numerical simulation. The actual deformation and failure of the casing are examined using on-site monitoring data, to which the numerical simulation results are then compared. We deduce that the tensile and shear failures occur at the lower part of the casing or at the bedding plane separation. Monitoring must be focused on these areas, and protective measures should be used. The numerical simulation model is simplified given various restrictions. The integration of numerical simulation and monitoring technology can serve as an efficient method for the quantitative analysis of failure on surface venthole casings. The research concepts presented in this paper and the rules deduced are useful references. © 2011 Elsevier B.V.


Rong G.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Jiang Q.-H.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Zhou C.-B.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Peng J.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | And 2 more authors.
Proceedings of the 10th International Conference on Advances in Discontinuous Numerical Methods and Applications in Geomechanics and Geoengineering, ICADD 10 | Year: 2012

According to the geological and slope structural conditions of the left bank in Jinping, hydropower station, the stability of the engineering slope is mainly controlled by a tensile rip rock body which is cut by the Lamprophyre X, the interior fracture SL 44-1 and the fault f 42-9. A systematic analysis of the excavation deformation of the left bank slope is performed in this paper, which includes the three dimensional discrete element simulation of excavation and support as well as the three dimensional limit equilibrium calculation of the tensile rip rock body. It has been found that there is no overall slip deformation in the tensile rip rock body after slope excavation. The deformation of the tensile rip rock body is mainly the result of the adjustment of the boundary deformation caused by the excavation unloading. The tensile rip rock body is stable during construction and the whole slope is also stable after excavation. The overall stability of the slope using the combined reinforcement of anchor cables and shear holes can meet the engineering demand. © 2012 Taylor & Francis Group, London.


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.


Ma G.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Ma G.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | Zhou W.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Zhou W.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | And 4 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

A stochastic granule model is developed at mesomechanical level. A random distribution model for rockfill granule is generated by means of random simulation technique. In addition, the nonlinear contact algorithm is presented based on modified augmented Lagrangian algorithm. A simple linear softening damage model is employed to describe the stress and strain relationship of mesoscopic element, and the mechanical properties are distributed with a certain statistical function. The stochastic granule model of Maokou rockfill of Shuibuya rockfill dam is established. The simulated results show that the movement and deformation processes of rockfill granule agree well with the present experiments.


Peng J.,Wuhan University | Peng J.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | Rong G.,Wuhan University | Rong G.,Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering | And 4 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

A negative exponent empirical model was proposed to express mi as a function of confinement and triaxial compression test data of various rocks are used to fit parameters of this model. Finally, parameter values in this empirical model and factors that influence these parameters were discussed. The results show that the new empirical model fits the test data better than the constant mi model for intact rocks. Constant mi model fits the test data well in the high confinement region but fails to match data well in the low confinement and tension regions. In particular, it overestimates the UCS and the uniaxial tensile strength of rocks.


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.


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.


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.


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.

Loading Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering collaborators
Loading Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering collaborators