采用数值分析方法，研究开挖卸荷引起的基坑围护墙竖向变形机理.在有限差分软件中建立考虑土与结构共同作用的分析模型，采用理想弹塑性接触模型模拟墙土接触力学特性，对比分析了3种土体参数下墙体和墙底土体竖向位移、墙土相对位移和墙体两侧摩阻力分布特性.结果表明：墙体的竖向位移主要由墙底土体竖向隆起和墙土相对滑动共同决定；坑底土体位移主要受到土体卸荷回弹的影响，与土层参数关系较大；当黏聚力增大时，墙体的下沉量减小；砂土的摩擦角越大，墙体的竖向隆起量也越大；墙土相对滑动则受墙体两侧的摩阻力共同作用，而摩阻力受参数取值的影响；当接触属性变强时，坑内摩阻力上升的趋势将增强，墙体发生的竖向隆起量也显著增加.
The numerical analysis method is adopted to study the vertical deformation mechanism of the retaining wall caused by unloading. A hypothetical model which considers the interaction between wall and soil, is established in the finite difference software. The ideal elastoplastic model is adopted to simulation the characteristics of contact property between soil and diaphragm wall. The vertical displacement of soil, the relative displacement of soil and wall and the distribution of friction under the 3 kinds of soil parameters are compared and analyzed. The results show that the vertical displacement of the wall can be divided into two parts the soil rebounded one and relatively sliding between subsoil and wall tips. The displacement of soil is mainly affected by unloading effect which is determined by soil parameter. The settlement of the wall decreases with the increase of soil cohesion. The uplift of the wall increases with the increase of friction angle. The relative sliding of wall tips and soil is governed by the frictional forces on two sides of the wall. With the increase of contact property, the frictional force increases and will lead to larger vertical displacements.
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