地下连续墙施工影响应力重分布的数值模拟

对武汉市某超大型超深基坑10幅邻近地连墙跳跃式施工过程进行了三维有限差分数值模拟。数值模拟步骤依次为泥浆护壁成槽开挖、混凝土浇筑及混凝土硬化3个过程。泥浆护壁成槽开挖及混凝土浇筑分别采用常静液压力和变静液压力的方式加载，混凝土的硬化过程采用变弹性模量和泊松比的线弹性实体单元完成。数值计算结果与实测数据吻合较好。对单个跳跃式开挖过程墙上土压力的监测揭示了地下连续墙施工影响应力重分布的变化规律。模拟施工完成后10幅地下连续墙上的土压力值沿墙长度方向随静止土压力值上下波动，波谷出现在槽段连接处附近，波峰接近槽段中心轴，波动幅度大小与土体深度有关。分析表明，泥浆压力、混凝土灌注压力及土压力差值是影响墙后应力重分布波动幅度的主要原因，适当的泥浆重度及合理的注浆方式能避免土体扰动。

Numerical simulation of stress redistribution during diaphragm wall construction

The construction of ten adjacent panels of a diaphragm wall of an ultra deep excavation in Wuhan city is simulated by a three-dimensional finite difference method. The construction procedure consists of the excavation supported by slurry, concrete pouring, and concrete hardening. The excavation is simulated by the constant distributed hydrostatic pressure while the concrete pouring process adopts variable distributed hydrostatic pressure. The concrete hardening process is finished by linear elastic solid elements with variable elasticity modulus and Poisson ratio. The results of the numerical computation show good agreement with the field test data. According to the process of single jumping excavation, the pressure monitoring reveals the influence of diaphragm wall construction on stress redistribution. The earth pressure fluctuates along the retaining wall after the construction completion of the ten panels. The peak value appears in the middle of the panel, while the trough value appears around the junction of two panels. The fluctuation range is related to the depth. The differences between slurry pressure, concrete pouring pressure and earth pressure are the main reason influencing the redistribution of earth pressure. Reasonable slurry unit weight and ideal concrete pouring method are suggested to avoid disturbance of soils.