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Gao C.-Y.,University of Sichuan | Xu J.,University of Sichuan | Li Z.-H.,Chengdu Hydroelectric Investigation And Design Institute | Deng J.-H.,University of Sichuan
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

The sandy slate samples are taken from the Xuefeng mountain tunnel rock. To study the effect of micro-bedding on strength properties and deformation characteristics of samples, a series of uniaxial and triaxial compressed tests are carried out with MTS815 Flex GT rock mechanics test system. The experiment results show that mechanical properties of the rock is obvious anisotropy. The stress-strain curves display unstable broken feature when the bedding parallels to axial stress (angle 0°) and failure faces development along the bedding. Softening rapidly happened after peak when the bedding is perpendicular to axial stress(angle 90°) and failure faces belongs to shear failure. The numerical results of uniaxial test show that compression strength, elastic modulus and deformation modulus of angle 0° is 20%, 50% and 80% higher separately than them of angle 90°. The results of triaxial test show the principal stress difference of them is close in the peak intensity; elastic modulus and deformation modulus of angle 0° is 6% and 20% higher than them of angle 90°. Confining pressure of triaxial tests has weakening effects on anisotropic features of the sandy slate. These conclusions reveal the sandy slate possesses anisotropic mechanical properties and offers important reference to solve practical engineering problems.

Lin P.,Tsinghua University | Ma T.,Dalian University of Technology | Liang Z.,Dalian University of Technology | Tang C.A.,Dalian University of Technology | Wang R.,Chengdu Hydroelectric Investigation And Design Institute
Engineering Failure Analysis | Year: 2014

A code of practice for three dimensional cracking and a failure process analysis of high arch dams, based on the finite element method, dam failure process analysis (DFPA) has been developed. In this code, by changing mesh density, consideration of heterogeneity when calculating the elements is achieved. Random strength and elastic modulus are assigned to the elements in accordance with a Weibull distribution. A stress analysis is carried out based on consideration of the deformation of an elastic material containing an initial random distribution of microcracks, which simulates the progressive failure of solids. The dam cracking and failure process associated seismicity accumulation can be analyzed using acoustic emissions. The proposed method was applied in investigating the failure mechanism, and overall stability of the Xiluodu high arch dam. The numerical mesh model was fine, and the total number of hexahedral elements was 300. million. The DFPA analysis results, when compared with those derived by the Tfine code, and the 3D geomechanical model test show that the DFPA code is effective in fully simulating the failure processes of the dam and foundation. The analysis results were used to successfully guide the design of the Xiluodu high arch dam. The proposed DFPA method may also be of value to the reinforcement design and construction of high arch dams, associated with similar hydropower projects worldwide which are also located in complicated rock foundation areas. © 2014 Elsevier Ltd.

Lin P.,Tsinghua University | Liu X.,Tsinghua University | Zhou W.,Tsinghua University | Wang R.,Chengdu Hydroelectric Investigation And Design Institute | Wang S.,University of Newcastle
Arabian Journal of Geosciences | Year: 2015

The aim of this study is to examine cracking and instability of the high and steep left bank slope with weak rock mass structures, and effectiveness of the reinforcements designed for the slope at the Jinping hydroelectricity power station, southwestern China. A new geomechanical model testing method is first proposed for evaluating slope safety factors. In the proposed geomechanical model test, the slope is constructed on a flat testing bed, which can be rotated by hydraulic lifts. By increasing the rotation angle of the testing bed, the forces tending to induce the sliding of the slope are increased, which may cause crack initiation and propagation in the slope and result in rock mass slippage. Thus, through the proposed geomechanical model test, the slope failure mechanism, progressive failure process and final failure pattern can be studied. Moreover, the stability safety factors can be evaluated according to displacement data monitored by sensors installed in the geomechanical model. The geomechanical model test of the Jinping left-bank slope reveals that the bending and toppling cracks occur simultaneously in the unreinforced zone of the slope together with strong relaxation and tension cracks. It is found that the factor controlling the rock mass failure and instability is the structurally weak rock mass and the dominant failure mode is the integral catastrophic instability mode, in which the slope energy is totally dissipated and the slope destabilizes at a limit state. The reinforcement installed in the large area above the elevation of the dam-slope abutment and the unloading action due to the excavation of rocks lying above the dam platform have effectively improved the anti-slide safety factor of the slope, and thus increased its inherent safety factor. On the basis of the geomechanical model testing results and their comparisons with field monitoring results, it is concluded that the installed rock bolts and long anchor reinforcement measures are very effective in keeping the cracks closed in the rock mass and maintaining the slope stability. © 2014, Saudi Society for Geosciences.

Qi Z.-F.,Wuhan University | Jiang Q.-H.,Wuhan University | Tang Z.-D.,Chengdu Hydroelectric Investigation And Design Institute | Zhou C.-B.,Wuhan University
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

The geological conditions of the high and steep abutment slope at left bank of Jinping-I Hydropower Project are very complicated, mainly developed with the faults of f 5, f 8, f 42-9, the lamprophyre veins of X, the release fractures oriented parallel to slope surface and deep fractures. The combination of the fault of f 42-9, the lamprophyre veins of X and the deep fracture of SL 44-1 form a tensile dehiscent deformable body at the abutment slope of the left bank; the stability of the abutment slope is very bad during construction, especially when the slope is excavated to the elevation of 1 780 m, all rock masses that prevent the tensile dehiscent deformable body from sliding are excavated; the outcrop of the fault of f 42-9at the surface of the excavated slope makes the stability of the tensile dehiscent deformable body abruptly become worse. The strength reduction FEM considering excavation process is applied to calculate the stability safety factor of the abutment slope; and a new slope instability criterion is proposed as follows: in finding the mutant site on the relationship curves between Δδ/ΔF t of key points and the strength reduction factors, the critical state of instability of the slope could be determined; in this criteria, Δδ/ΔF t, which stands the change rate of horizontal displacement with the strength reduction factors, is the ratio of the horizontal displacement's increment and the strength reduction factor's increment. Comparing with other slope instability criteria, a new criterion is proved to be a reasonable and practical slope instability criterion; based on this criterion, the stability safety factors are calculated when the slope is excavated and reinforced to different elevations; the overall stability and security of the abutment slope at the left bank are reasonably evaluated during its construction.

Zhou D.,Hohai University | Mi Z.,Hohai University | Mao Y.,Chengdu Hydroelectric Investigation And Design Institute
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2013

Sediment deposition in the pumping station has a huge negative impact on unit operation. 3-D CFD method was used to simulate pumping station inlet structure flow based on Eulerian solid-liquid two-phase flow model. Numerical results of preliminary scheme show that sediment deposition occurs in the forebay of pumping station because of poor flow pattern therein. In order to improve hydraulic configuration in the forebay, one modified measure was reconstructing water diversion weir shape, and another measure was setting a water retaining sill in the approach channel. The simulation results of modified scheme prove that back flow in the forebay was eliminated and sediment deposition region was also reduced greatly.

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