逆作法施工盆式开挖预留土体坡肩宽度的研究

逆作法施工中在地下连续墙内侧留设合理的预留土体，采用盆式开挖可以提高机械挖土效率，加快挖土速度，也是控制地下连续墙变形的一个有效方法。作者采用按变形控制计算盆式开挖预留土体坡肩宽度的方法，对上海长峰商城基坑留设不同坡肩宽度预留土体时的盆式开挖进行了三维有限元分析。计算结果表明，增大预留土体坡肩宽度对减小地下连续墙的水平变形有一定的效果，但是随着预留土体坡肩宽度增大到一定值时，再继续增大预留土体坡肩宽度对减小地下连续墙水平变形的效果就不明显。文章为逆作法盆式开挖施工中地下连续墙边预留土体坡肩宽度提供了一种有效的计算分析方法。

A Study on Obligating Width of Soil Slope Shoulder in Basin Opening for Top-down Construction Method

The top-clown construction method is an effective method. For in the course of building, if rational soil width is remained beside the diaphragm walls in top-down construction method, the excavation efficiency of machine can be improved, the excavation quantity of manpower reduced, the opening speed expedi- ted, and the distortion of diaphragm walls can be controlled effectively. In this paper, the method of calculating the obligating width of soil slope shoulder by controlling distortion is introduced to study different obligating width of soil slope shoulder in Chang Feng shopping center through 3D FEM method. Results show that adding obligating width of soil can reduce level distortion of diaphragm walls evidently, but the effect of reducing the level distortion of diaphragm walls will be unconspicuous when the obligating width of soil is increased to definite value. Thus, an effective analytic way is provided for the calculation of obligating width of soil slope shoulder beside diaphragm walls in top-down construction method.