软土地区深基坑工程存在的变形与稳定问题及其控制——基坑施工全过程的稳定问题

Stability and Deformation Problems During Deep Foundation Excavation in Soft Soil Area and Their Control Measures——Stability Problems During the Whole Process of Excavation Construction

对基坑施工全过程可能产生的稳定问题进行了分析,指出了复杂深基坑的稳定问题复杂性。根据基坑失稳的直接引发因素划分为基坑支护结构施工引发的稳定问题、坑内外土体形成滑动面引发的稳定问题、竖向支挡结构(排桩、地下连续墙等)破坏引发的基坑稳定问题、水平支撑(锚杆)系统破坏引起的基坑稳定问题、水平支撑的竖向支承系统(立柱)破坏引发的稳定问题和地下水引发的稳定问题6类,对其失稳机理、危害、治理措施进行了分析。最后,提出了基坑支护结构体系的冗余度设计概念和分类。

The stability problem must be carefully examined to minimize the impact of excavation on surroundings when deep excavation urban area is surrounded by various buildings,roads,buried pipelines and underground tunnels.The stability problems during the whole process of excavation are discussed and the complex of stability failure of braced deep excavation is illustrated.Based on the element whose failure directly leads to the stability failure of brace excavation,the stability problems of braced deep excavation is classified into 6 categories,namely stability problem induces by construction of retaining wall,slip surface formed in ground,stability problem due to the failure of retaining wall,stability problem caused by the failure of horizontal struts,stability problem due to the failure of vertical columns supporting horizontal struts,stability problem due to and stability problem caused by underground water.The mechanism of the 6 categories of stability failure problems,the damage may caused by these stability failure problems and the countermeasures are analyzed.Finally,concept and classification of redundancy of retaining structure are presented.