基于单元体剪切面的坑中坑基坑临界间距判别方法

Discrimination Method of Pit-in-pit Excavation Critical Spacing Based on Unit Shear Plane

坑中坑基坑的开挖包含外坑的竖向开挖卸载和内坑的侧向开挖卸载,存在着对内、外坑围护结构间"中间土体"的双向开挖应力释放问题,内、外坑开挖的相互影响又使得开挖应力释放问题变得更为复杂,导致对围护结构上土压力的控制难度增加。针对坑中坑基坑的内、外坑开挖相互影响问题,通过理论分析,在单元体加载试验破坏面为剪切面的基础上,提出坑中坑基坑内、外坑开挖相互影响的临界间距判别方法,建立考虑土体强度的临界间距计算公式。通过离心机试验,验证基于单元体剪切面的内、外坑开挖相互影响临界间距判别方法的适用性。

The pit-in-pit excavation includes vertical unloading of outer pit and lateral unloading of inner pit, which made the earth pressure on bracing structure of pits become complex. The interaction between outer and inner excavation intensified influence of two directional stress release of pit-in-pit excavation. For the excavation interaction between outer pit and inner pit, based on loading test of unit, the discrimination method of critical spacing between outer pit and inner pit was put forward. Through centrifuge model test, the applicability and application of discrimination method of critical spacing was verified.