格栅状地下连续墙现场试验与基坑支护性能分析

相比于泥浆成槽法的传统实腹式地下连续墙,采用高频振动沉模成孔方式的格栅状地下连续墙的成墙效果和支护性能研究尚处于空白。首先,开展了软土地质条件下格栅状地下连续墙的成墙现场试验研究,继而采用有限单元方法计算得到了背景工程开挖全过程的墙体变形、地面沉降和坑底隆起等支护性能指标变化规律;分析了嵌固深度、地面超载、支撑截面等参数上述指标的影响性特征。结果表明,格栅状地下连续墙的墙身混凝土浇筑质量能够满足强度和抗渗性能要求;其支护性能与传统的钻孔桩和地下连续墙相近,仅截面刚度存在差异,因此可按照桩、墙结构进行设计;为完善结构构造和结点体系,应进一步开展试点工程的应用性研究。

Investigation on in-situ experiment and performance of grille diaphragm wall for foundation pit supporting

Compared with traditional solid grittle diaphragm wall grooved by slurry supporting, new grille diaphragm wall is grooved by steel mould which is impresed by vibration with high frequency. However, investigations of grille diaphragm wall on shaping effect and supporting property are still absent. Firstly, experimental investigation in situ of contructing grille diaphragm wall is conducted under geological condition with soft soil. Then, FE method was utilized for simulationg excavation precedure of background project, by which the supporting parameters are obtained, such as displacement of wall, ground settlement and bottom heave. The variation law of these three upporting parameters is analyzed and the influence of embedded depth, ground overloading and cross section of concrete support is investigated. The investigation indicates that the quality of concrete satisfies the quirement of anti-permeability and strength. The supporting performance of grille diaphragm wall approximates to traditional cast-in place pile and solid grittle diaphragm with difference on stiffness. Hence, grille diaphragm wall can be design as traditional cast-in place pile and solid grittle diaphragm. Additional investigation requires to be conducted on construction and joints details in the future.