某软土深基坑变形事故处理

Deformation accident treatment of a deep foundation pit in soft soil

本文以某项目大面积开挖的软土深基坑施工过程中,导致周边的别墅区内地面产生50-90mm缝隙、建筑物开裂为背景,对基坑施工造成临近地面过大变形和建筑开裂发生的原因以及发生基坑过大变形后的加固处理做了具体而深入的研究,主要研究工作和结论总结如下:基坑开挖成后在没有支撑条件下,呈现出明显的时间效应,地面沉降时程有四个阶段;运用多目标模糊优选理论择优选择对环境影响小、经济、工期短的加固方案,利用基坑的时空效应原理将基坑环境等级提升为一级,为了节约成本可分段设计安全等级和环境等级,基坑临近地面及建筑物变形要求较高时,基坑支护采用排桩加内撑比排桩加支护锚杆结构形式较为经济合理,控制变形更为可靠。

Based on the background of 50-90 mm gap and building cracking in the surrounding villa area caused by the construction of a large-area soft soil deep foundation pit. This paper makes specific and in-depth research on the causes of the near-ground deformation and the occurrence of building cracking in foundation pit construction, as well as the reinforcement and treatment after excessive deformation of foundation pits.The main research work and conclusions are summarized as follows: when the foundation pit is excavated without support, it shows obvious time effect and four stages of land subsidence;Based on the multi-objective fuzzy optimization theory, the reinforcement scheme with small impact on the environment, low cost and short construction period can be selected. The environmental grade of foundation pit can be upgraded to the first grade by using the principle of space-time effect of foundation pit. In order to save cost, the safety grade and environmental grade can be designed by sections. When the foundation pit is near the ground and the deformation requirements of the building is high, It is more economical, reasonable and more reliable to control deformation to use row piles and internal bracing in foundation pit support rather than supporting and supporting bolt.