关键词: 剪切带;混凝土防渗墙;接触面单元;剪切面单元;

Abstract: For earth core wall rockfill dams built on overburden layer, concrete cutoff wall is often used to prevent seepage in dam foundations.Concrete cutoff wall and soil core wall are the key parts of dams, and the calculation and analysis of their stress and deformation are related to dam safety.Since the compression modulus of the concrete cutoff wall is much higher than that of the soil on both sides of the wall, the settlement of the soil on both sides of the wall is much greater than that of the wall itself, resulting in generation of a shear zone with a sharp change of settlement inthe soil on the top of the cutoff wall.The simulation of shear zone in soil is related to the frontier theory of mechanics research, such as large deformation, strain localization and discontinuity, and the numerical simulation method is not mature.Therefore, this paper proposes a method to simulate the shear band deformation with a preset shear plane element to simulate the slip characteristics of soil when shear failure occurs, so as to solve the problem of simulating the shear deformation of soil at the top of rigid structure.The method is applied to the calculation of earth pressure at the top of the trench buried culvert, and the calculation results are basically consistent with the law of model test.Based on the finite element calculation of a typical dam project in which the cutoff wall is inserted into the soil core wall, the proposed method can better reveal the shear deformation characteristics of the soil on upper part of the cutoff wall, and the calculated vertical average stress value at the top of the cutoff wall is reduced by 30.43% compared with the conventional method, which can better solve the problem of the calculated stress of the cutoff wall that is larger than the actual monitored value.

Key words: shear zone; concrete cutoff wall; contact plane element; shear plane element;