Stability Abalysis And Reinforcement Method For Expressway Bedding Shale Slope

The stability of highway slope is the focus of research no matter home or abroad,and it is hot to discuss the stability of slope and choose the optimal reinforcement scheme.Based on the shale slope of the Zhangcheng highway,this paper made a preliminary judgment on the stability of the slope by collecting the basic geological data of the study area and combining with the field investigation.Then the stability of the slope was determined by the stereographic projection,and the unstable slope length was calculated.Based on PFC2D,the stability of slope was analyzed and the failure mechanism of slope was studied.According to the results of stability analysis,two kinds of reinforcement schemes---micro-pile and anchor frame beam---were proposed.The rein forcement effects were evaluated by discrete element method.The main contents and conclusions are as follows:1)The stability of the slope was determined by the field geological survey and the stereographic projection,which suggested the slope was unstable.The lateral length of the slope was 31.01 m and the depth of the trailing edge was 3.06 m.2)The relationship between the mesoscopic parameters and the macroscopic parameters was discussed.The results show that the elastic modulus and the tensile modulus of the samples are linearly increasing with the increase of grain stiffness.The parallel tensile strength,parallel bond,internal friction angle and friction coefficient have an influence on the compressive strength and tensile strength.This conclusion provides a theoretical basis for the determination of mesoscopic parameters of slope discrete element simulation.3)The numerical analysis of the slope was carried out by PFC2D,and the fully weathered shale layer in the slope slided downwards and piled up on the foot.The strong weathered shale and the moderately weathered shale did not slope.The sliding surface was the interface between the fully weathered shale layer and the strong weathered shale layer.The simulation results of the discrete element method are consistent with those of the stereographic projection method.4)As for unstable slope,two kinds of reinforcement schemes---micro-pile and anchor frame beam---are proposed.These two kinds of support schemes were numerically analyzed by discrete element method.Results show that both reinforcement schemes can effectively strengthen the slope,and the reinforcement slope was in stable state.But the effect of micro-pile reinforcement is much better than that of anchor frame beam.It is suggested that the micro-pile scheme should be adopted.