软土地区基坑支护结构失稳案例分析

A Case Study on Soft Soil Region Foundation Pit Support Structure Destabilization Analysis

武汉市某高层住宅地基为湖积软土-淤泥及淤泥质土,基坑南侧区段在开挖过程中,支护结构外软弱土体发生较大的蠕变变形,再加上南侧局部工程桩接桩,存在超挖现象,后由于基坑南侧场地外大量堆土,基坑南侧支护结构在土压力作用下,向基坑内侧发生较大的变形。通过基坑旁的监测点,记录了地表水平位移、深层水平位移和地表沉降曲线,结果表明:基坑南侧外堆土和双排桩间粉喷桩强度不能满足设计要求是变形发生的外因,土体中有机质含量较高,致使土体抗剪强度较低是变形发生的内因。

The foundation of a high-rise residential building in the Wuhan City is lacustrine soft soil-sludge and muddy soil. During the excavation,foundation pit south side sector support structure outside soft soil mass has happened large creep deformation. Coupled with south side local project piles need to be extended,existed over-excavation. Afterwards since massive pile of soil outside the foundation pit south side,support structure under the soil pressure,caused foundation pit inner side large deformation. Through foundation pit side monitoring points have recorded ground surface,deep-seated horizontal displacements and ground surface settlement curves.The result has shown that the foundation pit south outside soil pile and strength of the dry jet mixing pile between the double-row piles can not meet design requirements are the external cause of deformation. While the higher organic matter content in soil mass caused lower soil mass shear strength is the internal cause of deformation.