Abstract: 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.

Key words: Mohr circle of stress, internal frictional angle, cohesion, nonlimit state, horizontal slices analysis method