黏性土的非极限主动土压力计算方法研究

经典土压力理论只能计算挡土墙位移达到极限状态时的土压力。为了更贴近工程实际，需要发展非极性土压力理论，但以往的研究仅限于砂土。对于黏性土的非极限主动土压力，在已有成果的基础上，从黏性土的应力莫尔圆出发，推导了介于初始状态和极限主动状态之间的中间状态时，黏性土的内摩擦角? 随墙体位移变化的关系公式；同时考虑了墙土接触面上外摩擦角? 和黏聚力cw的影响，根据黏性土应力莫尔圆的几何关系得到了土体黏聚力c与墙体位移的关系；最后应用水平分层法求得了非极限状态时黏性土的主动土压力计算公式。与模型试验数据的对比分析表明，理论计算值和试验实测值基本吻合。研究表明，计算方法对于计算黏性土在非极限状态时的主动土压力具有一定的理论意义，在实际工程中也具有相应的实用价值。

Computational method for active earth pressure of cohesive soil under nonlimit state

The classical earth pressure theories can only calculate the pressure when the wall movement achieves the limit state. In order to match up to the practical situation, it is necessary to develop the earth pressure theories under nonlimit state. However, previous researches are only involved with the cohesion-less soil. Based on the existing results for active earth pressure of cohesive soil under nonlimit state, the relationship between the internal frictional angle ?，cohesion c and the wall movement is established according to Mohr circle of stress under the situation of intermediate active state. At the same time, considering the influence of wall friction angle ? and cohesive strength cw on the interface, the connection of cohesive strength c with wall’s displacement has been set up on the foundation of geometrical relationship in Mohr circle of stress. Finally, a new equation for determining active earth pressure of cohesive soil under nonlimit state is derived using horizontal slices analysis method. The value of calculation has an approximate agreement with the measured value of two model tests. The result shows that the proposed method has some theoretical significance in calculating active earth pressure of cohesive soil under nonlimit state and applied value in construction practice.