库区水位变动下白沙碉变形体稳定性研究

Research on stability of deformation body of Baishadiao under water level change in reservoir area

渗流场与应力场的耦合分析是库区水位变动下变形体稳定性研究的热点和难点问题。基于岩体不连续性的离散元方法可以模拟流体在不透水岩体之间的裂隙中的流动,是一种完全的流固耦合分析方法。以金沙江溪洛渡水电站右岸白沙碉变形体为研究对象,通过岸坡岩体力学特性试验给出参数建议值;在充分考虑岸坡区域地质条件特征的基础上,采用离散元方法的应力–渗流耦合分析理论,结合溪洛渡水电站水库调度曲线,研究库水位变动下变形体的稳定性变化过程,并开展基于渗流场计算的极限平衡对比分析。分析结果表明,随库水位增加,变形体的孔隙水压力不断增大,稳定性则逐渐减低;当水位为600 m时,变形体发生失稳;离散元与极限平衡分析结果基本一致,但离散元动态地反映水在裂隙中的流动过程,相对极限平衡分析更能反映实际情况。

Coupling analysis of the seepage field-stress field is a hot and difficult problem in the study of stability for deformable body under water level change in reservoir area. The discontinuum-based discrete element method is a fully fluid-solid coupling analysis method,which can simulate the fluid flow between fractures of the impervious rock mass. Taking the Baishadiao deformable body at right bank of the Xiluodu hydropower station in Jinshajiang river as a case study,the mechanical properties of rock slope parameters are obtained with various tests;according to the reservoir operation curve of the Xiluodu hydropower station,based on full consideration of the regional geological condition of the bank slope,stability analyzing of the deformable body under reservoir water level change has been carried out with the discrete element method;the limit equilibrium analysis based on the calculation of seepage field is also carried out for a comparative analysis. The simulation result shows that with increase of the reservoir water level,the pore water pressure increases,and stability gradually decreases;at a water level of 600 m,instability failure of the deformable body is observed;compared with the limit equilibrium analysis,the discrete element method considers the dynamic flow of the water in the cracks and can reflect the actual situation.