圆形基坑主动土压力的理论研究

Theoretical study on active earth pressure of circular foundation pits

考虑了地面坡度、墙-土间摩擦和墙体倾角同时存在的一般情况,提出两种破坏模式,采用滑移线法和简化滑移线法进行计算,给出了圆形基坑主动土压力的数值解和解析解。研究了土体的分层、地下水渗流、环向应力系数等对土压力结果的影响。认为在计算主动土压力时,环向应力系数为1是合理的,但该结果不能用于实际工程设计。设计中可考虑环向应力系数为一变量,其值在1和K_0之间变化,与其位置有关,采用滑移线法计算给出土压力系数的结果,以供参考。本课题的研究成果系统地发展了圆形基坑主动土压力理论,具有较强的理论和实际意义。

By using the slip line method and simplified slip line method,considering the combination of ground slopes, soil-wall interface friction and wall inclination,two failure modes were proposed and the numerical and analytical solutions of the active earth pressure of circular foundation pits were given.The effect of the layered soil system,the underground water seepage and the tangential stress coefficient on the earth pressure was discussed.It is concluded that when calculating the active earth pressure,taking the tangential stress coefficient as a unity is reasonable,however,the results obtained accordingly cannot be used in the design.In practice,it is better to consider the tangential stress coefficient as a variable,varying between 1 and K_0, and its value depends on the position.The active earth pressure coefficients were obtained by use of the slip line method and the results could be referred in practice.The present study develops the theory of the active earth pressure of the circular foundation pits,and has a great significance in theory and in practice.