Study On Stability And Seepage In Dam Foundation Of Shuangwangcheng Reservoir

On the basis of the acquired geological data, finite-element-method (FEM) static stress analysis, seepage analysis and slope stability analysis have been carried out on the dam foundation profile type under the predetermined scale of the reservoir. In FEM static stress analysis, stress levels in the dam box are calculated at the completion of the dam, during the normal impounding period and the counterweight-impounding period. All the values are less than 0.95, which indicates that shear failure will not occur in the selected unit. Therefore, the selected profile of dam body and imperious countermeasures in the dam foundation meet the engineering requirements. High-stress zone is located at the bottom of the dam body and in the superficial layer of the dam foundation right beneath the dam top. At the dam's completion, stress level values of all units form a plane symmetric to the vertical line corresponding with the dam top, while the symmetric axis shifts downstream during the normal impounding period and the counterweight-impounding period. After the counterweight platform is constructed on both sides of the dam body, stress in the dam foundation diffuses, which shows that the counterweight platform enhances the stability of the dam body, and hence it solves the liquefaction problem of sandy soil in the dam foundation. Analytical results also show that stress diffusion and concentration occur between the relatively hard layer and the relatively soft layer of dam soil body. Stress levels of the impervious wall vary unconspicuously under the three conditions. Seepage analysis results show that under natural conditions severe leakage occurs in the dam foundation but leakage is reduced after the imperious measures are taken, and so the imperious result is satisfactory. Under the conditions of the selected dam profile, results of stability calculation of dam slope meet the requirements of Codes and Standards, and are very close to the allowable value. Therefore, the design of the dam profile is economic and reasonable, and meanwhile, understanding of sandy soil and countermeasures are right. The study has arrived at satisfactory theoretical results and bears some theoretical significance in guiding dam construction in soft soil foundation in plain areas.