沉井下沉时土压力和侧壁摩阻力分析

Earth Pressure and Frictional Resistance Analysis on Open Caisson During Sinking

摘要:

基于极限平衡状态和平面滑裂面假定，推导出单一非黏性土层中沉井下沉时的土压力和侧壁摩阻力计算公式，采用等效内摩擦角和等效自重应力的方法将其推广至成层黏性土层中，并与某工程实测数据进行了对比分析.结果表明，沉井土压力和侧壁摩阻力随着土体内摩擦角的增大而减少，随着土体与沉井壁的外摩擦角的增大而增大；滑裂面的滑裂角随着外摩擦角的增大而增大，随着内摩擦角的增大先减少后增大；理论推导的土压力接近实测土压力，且基本介于主动土压力与静止土压力之间；实际工程中，在预估侧壁摩阻力时，可以考虑12 m深度以下保持不变.

Abstract:

Based on the limit equilibrium theory and the hypothesis of planar sliding plane, formulae were deduced to calculate open caisson earth pressure and frictional resistance during sinking on single non cohesive soils. Then the formulae were extended to layered cohesive soils by the methods of equivalent internal friction angle and self weight stress. The calculations were also compared with the measured data of a project. The results show that the earth pressure and frictional resistance decrease while internal friction angle increases, and increase while external friction angle increases. Sliding plane angle increases while external friction angle increases, decreases initially and then increases while internal friction angle increases. The theoretically deduced earth pressure between active earth pressure and earth pressure at rest is close to the measured earth pressure. In the actual projects, side wall frictional resistance can be considered unchanged below the depth of 12 m.