Research And Application Of Stability Analysis Method Of Complex Slope Under Rainfall Conditions

The landslide is one of the three major geological hazards in the world,the consequences of which seriously threaten the production and life of human beings and cause huge economic losses to the area.Rainfall will lead to the increase of soil weight,decrease of shear strength and decrease of matrix suction,which will reduce the stability of slope and eventually lead to the landslide.Therefore,the study of slope stability under the action of rainfall is of great benefit to both national economy and national security.In this paper,based on unsaturated seepage theory,multiple homogeneous slopes and models of city walls and terraces are used as examples to study the stability analysis methods of complex slopes under rainfall conditions by means of conventional tests and numerical simulations,and the main research contents are as follows.(1)Based on the unsaturated seepage theory,the soil-water characteristic curve of the wall soil was obtained by the filter paper method test with the Panmen wall in Suzhou as the object,and based on this,the stability change of the wall and the internal pore water pressure distribution under various working conditions were analyzed,and the prediction curve of the stability safety coefficient of the Panmen wall with the change of rainfall intensity and rainfall duration was obtained.Taking the unique plum rain climate in the middle and lower reaches of Yangtze River as typical,it provides theoretical reference for the design and construction of the wall repair and other projects in this region under typical regional climate conditions.(2)Based on the indoor direct shear test data,we determine the matching reduction mechanism of cohesion c and internal friction angle under different water content conditions,propose a comprehensive safety factor definition formula with water content as the variable,and verify the rationality and reliability of the double strength reduction method through several homogeneous slopes.The results of the double-strength reduction method and the generalized bar separation method based on the double-strength reduction method under the action of rainfall are calculated and compared with those of the traditional generalized bar separation method using the wall and the terraces as models,respectively.(3)Based on the random field theory,the influence of different influencing factors on the stability and reliability of slopes is analyzed through the calculation of homogeneous slopes,walls and terraces.The results show that the deterministic method of slope safety analysis cannot reasonably and comprehensively evaluate the slope stability,and it is easy to overestimate the slope safety,and the influence of spatial variability of soil strength should be considered in the calculation.Based on the random field theory,combined with the landslide volume and slip surface form,the risk of slope instability can be better evaluated.