土压力计算中几个问题的探讨

On several issues existed in earth pressure calculation

针对土压力计算中传统土压力计算方法的适用性问题、考虑墙体位移的土压力计算问题、不同墙体变位模式下土压力计算问题和水土压力的分算与合算问题,进行了详细的分析与探讨.指出基于极限平衡理论的传统土压力理论与实际出入较大,而现有的考虑墙体位移的土压力计算模型,实质是对主动和被动土压力的非线性插值,是对传统土压力理论的修正;条带平衡法能够导出土压力沿墙背的分布解,与考虑墙体位移的土压力模型结合,可综合考虑墙体变位模式与墙体位移对土压力的影响.关于基坑支护结构上的水土压力,对于沙土可采用水土分算法;对于黏性土,宜采用经以塑性指数与液性指数有关的系数修正的混合算法,从而避免出现夸大或低估静水压力的现象.

Several main issues existed in earth pressure calculation,were analyzed and discussed in the paper. including the applicability of traditional earth pressure theory,the earth pressure calculation of retaining wall displacement,the earth pressure under various movement modes,estimating water and earth pressures separately or together. The traditional earth pressure theory,based on the limit equilibrium theory,has many differences comparing with the practice. The existing earth pressure calculated model considering the retaining wall displacement is a non linear interpolation between active and passive earth pressure essentially,and it is only a revision of traditional earth pressure theory. The distributing solution of earth pressure can be obtained by strip equilibrium method,and it can synthetically consider the influence of wall displacement and movement modes if combined with the displacement model. On water and earth pressure,the estimating water and earth pressure separately can be adopted on sandy soil. The hybrid method,which is revised based on plasticity index and water plasticity ratio,can be adopted on clay,and phenomena of overestimated or underestimated hydrostatic pressure can be avoided.