Determining of potential failure surface in safety analysis of rock slope under bridge load

Many canyon bridges are designed in mountain railways. Limited by bridge span, foundations position of canyon bridges are near slope surface. Under great load of bridge, shear failure may occur in slope. And the potential failure surface is the basis of reinforcement. In this paper, based on model test, the reason of shear failure is analyzed with strength theory by numerical method, the influence of load on rock mass stress of slope surface is analyzed also. A stress influence angle which is 55 degrees is obtained. According to stress influence angle a nd bridge foundation position, the front edge and the back 'edge of the potential failure surface is determined, so the potential failure surface is obtained. The method based on stress influence angle is convenient in applying in practice. And it can provide a reference to reinforcement of slope under bridge load.