Research Of Stability Of Earth Slope And Early-Warning Prediction Under Heavy Rain Based On The Failure Mood Analysis

Reinforcing slope with supporting structure is an important engineering measure to improve slope stability and prevent potential landslide from happening.Among these supporting structures,anti-slide pile and retaining wall are the most commonly used in slope engineering.While supporting effect differs from supporting parameters,analyzing the change law of slope stability under different supporting parameters is the basis in slope supporting.Based on the strength reduction method and 3D FEM,the supporting effects of retaining wall,anti-sliding pile and combined supporting structure on a slope project are analyzed respectively from multiple perspectives.The influences of different rainfall patterns on slope displacement characteristics under heavy rainfall are analyzed and the supplementary early-warning index of vertical displacement direction rate is established based on the failure mode analysis.The main contents of this paper are as follows:(1)The feasibility of strength reduction method in slope stability analysis is verified by comparing the results of using upper bound limit analysis,lower bound limit analysis and limit equilibrium method analysis.On this basis,the failure mode of unreinforced slope is analyzed using the displacement vector based on the results of slope stability analysis by strength reduction method and the failure mode is verified by the analysis of stress field and displacement field under deformation state.(2)The supporting effects of retaining wall,anti-slide pile and combined supporting structure are analyzed respectively using the strength reduction method.Besides,the changing laws of the critical slip surface of the slope,failure mode of the slope,stress characteristics of the pile and safety factor of the slope are studied while adopting different pile location,pile length and pile spacing.Based on the comprehensive analysis and confirmation of these parameters,the schemes of adopting anti-slide pile and combined supporting structure suitable for this project are selected.(3)Based on the analysis of the failure mode of the reinforced slope,the feasibility of using the vertical displacement directional rate to supplement the early warning index is demonstrated.Four types of rainfall processes are designed with the total rainfall and rainfall time unchanged referring to Tianjin "720 heavy rainfall".Based on the quasi 3D FEM,the changing law of the slope displacement and directional rate of vertical displacement under different rainfall types are studied,and the early-warning time is obtained under four kinds of rainfall which can reflect the failure process.Based on the analysis of the developing law of the vertical displacement directional rate at the tensile crack on the top of the slope during a typical heavy rainfall process and the previous analysis of the failure mode of the slope,an early-warning index of the vertical displacement directional rate of the slope is established based on the division of the instability process which can reflect the process of the slope instability.