The Study On Water Damage Mechanism And Reinforcement Of Red Sandstone Slope With Weak Layers

In recent years, landslide accidents often occurred on expressway with red sandstone distributed, resulting from continuous rainfall and weak layers, et al. In this paper, Changji Section K1193of Hangrui Expressway was taken as the engineering background. Considering seepage law, an improved movable mechanism method was proposed, based on which the stability of landslide slope with weak layers can be evaluated. And a group of orthogonal tests were designed to investigate the landslide mechanism of this type of slope and analyze the influences of weak layer properties on red sandstone slope stability. Finally, based on these theoretical research and experiments, a new water drainage approach was proposed to control landslide. The main contributions of this work included:(1) The seepage law of weak layer was studied. Results showed that when water head of pore water pressure is higher than the thickness of weak layer, pore water pressure presented a linear reduction. However, when water head of pore water pressure is lower than the thickness of weak layer, pore water pressure would decrease in quadratic form. Based on the rules summarize above, an improved movable mechanism method was put forward, and the criterion for slope stability was derived finally.(2) A group of model experiments of red sandstone slope with weak layer were accomplished according to similarity principle and orthogonal experiment criterion. Taken weak layer buried depth, dip, cohesive strength and initial water capacity as independent variables, seepage field in weak layer and slope stability were studied. Results showed that weak layer buried depth, dip had great influence on seepage field; the slope stability was proportional to weak layer buried depth and cohesive strength but inversely proportional to dip; when initial water capacity equal to optimum water content, the slope has the higher stability.(3) The failing load gained from model experiments could be transformed to depth of trailing edge crack water (failing value). The practical slope stability could be evaluated by comparing its specific depth of trailing edge crack water with failing value. The result was consistent with that of the proposed theoretical slope stability discrimination method. It proved that theoretical method was applicable for evaluating stability of red sandstone slope with weak layer.(4) Based on drainage model experiment, a new landslide control method was proposed, i.e. division cutting and integrated drainage. The proposed theoretical slope stability discrimination method was adopted to analyze the reinforcement performance of the water drainage approach. Result showed that energy coefficient was increased from0.94to1.19. This proved that the method does well in landslide control.