Analysis of the Influence of Valley Deformation on the Safety of Xiluodu Arch Dam

The valley shrink deformation phenomenon of Xiluodu arch dam is more obvious during initial impoundment. By the end of May 19, 2017, the VDL04 line of Valley width deformation reached 62.45mm in dam crest, far exceeding the value of similar projects. It is necessary to study the trend of Valley shrink deformation and its influence on arch dam safety. On the basis of the function fitting and convergence prediction of valley deformation, nonlinear finite element boundary displacement overloading method is applied to simulate developing valley deformation. A method of applying incremental shrinkage valley deformation is adopted to study the stress, deformation and plastic zone change of arch dam and foundation and to analyze the weak parts and failure modes of dam and foundation. The safety evaluation of dam under the condition of valley shrinkage deformation limit is carried out. The results show that with the valley width deformation overload multiple increases, downstream dam surface under 420m constraint region produces tensile and shear failure zone under dead water level condition and generate the left and right two plastic branches in the downstream surface of dam above 420m, which expand along near the left and right side of the arch abutment to the upper elevation and expand to the interior of dam and arch crown beam. At the same time, the upstream dam surface has developed the upstream shear and tensile failure zone at the 550m elevation of the arch crown beam, and the symmetrical extension is presented. Research shows that the valley displacement results in a significant increase in the plastic volume of the dam body under the normal water condition when the valley width overload multiple reaches Kcz=3.0 (VDL04 Valley width line displacement is -22.436cm), the valley displacement results in a significant increase in the plastic volume of the dam body under the dead water condition when the valley width overload multiple reaches Kcz=2.0 (VDL04 Valley width line displacement is -14.972cm).