Nonlinear creep damage model considering effect of pore pressure and analysis of long-term stability of rock structure

Water changes natural seepage in the surrounding geological environment and weaken rock mass of valley during reservoir impounding, which result in large time-dependent deformation of foundation of dam. A nonlinear creep damage model considering water effect is proposed by taking into account the influence of pore pressure on the spherical stress tensor and yield surface. The elastic-viscoelastic model is consisted of a spring and several cascaded Kelvin models. The model is implemented in the ABAQUS user material subroutine. The accuracy of the model is verified by the triaxial creep test of saturated sandstone and dry sandstone. Then it is applied in the valley contraction analysis during impounding of Xiluodu high arch dam.

Impounding in Advance for Three Gorges Reservoir by Considering the Downstream Drought Resistance

To solve the contradiction between Three Gorges reservoir impounding and downstream drought resistance in flood recession period, impounding in advance scheme is studied in this paper. Firstly, an improved impounding mode by strictly satisfying the downstream drought resistance discharge constraints is proposed. Then, by comparing from the aspects of annual average fill storage rate, final water level, power generation, surplus water and flood risk of different impounding time schemes, the optimum improved impounding scheme is determined and validated by typical year 1996. The study can proved scientific guidance for drought control of Three Gorges reservoir.

FEM Simulation of Temperature and Thermal Stress of Xiaowan Arch Dam

Taking all the effects into account of thermal and mechanical properties, construction process, environment temperature, arch-closure and reservoir impounding orders, three dimension (3D) finite element methods(FEM) was adopted to simulate the whole construction process for temperature changing and thermal stress distribution of the dam. Typically, the results of the highest 22nd monolith were analyzed, from which the general law for both temperature field and thermal stress was acquired. And the results are valuable for temperature control of Xiaowan high arch dam.

Deformation Characteristics of a Preexisting Landslide in Reservoir Area during Reservoir Filling and Operation

A monitoring system was implemented to monitor the hydrodynamic and deformation response of a preexisting landslide in the Three Gorges Reservoir area. The monitoring results indicate that the deformation is mainly caused by reservoir impounding and is mainly composed of the deformation of the slip band. The effect of reservoir level fluctuation on landslide stability mainly depend on two aspects, one is the change of shear stress and shear strength on the slip surface due to the change of slide body weight and pore water pressure, the other is seepage pressure.

Analysis on Formation Mechanism and Stability of Nierwan Landslide in the Three Gorges Reservoir Area

Suffering the influence of the Three Gorges Reservoir impounding, Nierwan landslide already has produced very big transmutation, whose destructiveness and influence are great and wide. First, this paper introduces the characteristics of geology, structure and deformation of the landslide. On the basis of the study mentioned above, the formation mechanism and influencing factors of the landslide are deeply analyzed. Finally this paper adopts transfer coefficient method to calculate and evaluate the stability. According to study, the landslide is in the status of creeping or failure. So Nierwan Landslide needs to be controlled recently.