Determination of the slip surface by load data measurement system and strength reduction of 3D FEM

In order to know the variation of the slope stability under external slide thrust, the soil load cell was preferred on the test platform of large-scale physical model to measure the stress in the slope body for the first time. Adopting the method of limit analysis of FEM by step load, the The external slide thrust was enhanced step by step with the method of limit analysis of FEM by step loads, the limit condition of the slope body stabilized on the certain work condition could be gained in a certain time to a certain size of the thrust. The results of the two analysis method were shown out as follows. As the slide thrust was enhanced step by step, the soil stress in slope body was enhanced increased steadily. When the external thrust was increased to a certain magnitude, the tendency in of development of the soil stress in the slope body was inflected varied, which disclosed the structural changes and the stability progress state changed from steadily state to failure in the inner body of the slope. From the curve of the soil stress vs. time, the time and the location that the slide surface formed could be determined. The method of limit analysis of FEM by step load could be used to estimate the shape of the slide surface. The shape computed by FEM was identical to the measurement by the soil load cell.