| The Xiashan landslide,which is classified as a typical basalt platform landslide,is the most massive landslide in Zhejiang Province,China.Based on the latest survey results and relevant data of the Xiashan landslide,combined with the latest monitoring data and field investigation,this paper makes theoretical research on the cause of formation and failure mechanism of the Xiashan landslide.It is found that rainfall is the main influencing factor of the landslide,and the tensile cracks at the back edge of the landslide also have an important impact on the stability of the landslide.In order to obtain accurate tensile strength parameters of rock and soil,the influence of loading angle on the Brazilian splitting test is analyzed by using finite element software ANSYS,and the optimal loading angle of the Brazilian splitting test under arc loading is studied.According to the modified tensile strength,the shear strength parameters are calculated.The numerical model of the typical section of the Xiashan landslide with different rainfall intensity is constructed by using the finite element software MIDAS GTS NX to analyze the influence of rainfall on the stability of the Xiashan landslide.The main conclusions are as follows:(1)Based on the geological conditions and landslide characteristics of the the Xiashan landslide,the causes and failure mechanism of the landslide are analyzed from the history,current situation,geotechnical characteristics,rainfall and human activities.It is found that rainfall is the main influencing factor of the landslide.It is speculated that the landslide will continue to slide,and the subsequent deformation is mainly in the creep mode.Under general conditions,the possibility of overall speed sliding is not large,but the local sliding speed of the front edge will be accelerated when the rainfall is persistent or heavy.(2)The finite element software ANSYS and the theoretical calculation formula of the Brazilian splitting test are used to calculate the Brazilian splitting model under concentrated loading respectively.It is found that the error between the numerical solution and the theoretical solution of the stress near the center of the circle is small,which indicates that the numerical simulation can simulate the Brazilian disc splitting test well.It is found that with the increase of the loading angle,the horizontal tensile stress at the center of the disc decreases,the increasing rate of the compressive tensile stress ratio accelerates,and the maximum compressive tensile stress ratio decreases.Considering the arc loading,the optimal loading angle 2? ranges from 18.4 ° to 27.8 °and the corresponding tensile strength correction coefficient ranges from 0.951 to0.974.(3)The latest monitoring results show that the slope is in a creeping state.Analyzing the rainfall data of the landslide area in the recent 30 years,it is found that the rainfall and rainfall frequency in the landslide area has an increasing trend,and the probability of heavy rainstorms in the landslide area is very high.Based on the relationship between tensile strength and cohesion,tensile strength and internal friction angle,the shear strength parameters are calculated with the modified tensile strength value.Based on the numerical analysis method,the Midas slope model considering both rainfall and groundwater conditions is constructed.The results show that the slope is in the stage of under stability.It is suggested that the landslide should be controlled mainly by water control and integrated with engineering measures. |
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