Study On The Stability Of High Fill Slope In Unsaturated Loess Under Rainfall Infiltration Conditions

Loess as a typical unsaturated soil,the unsaturated soil has an important influence on the stability of loess slope.With the implementation of the “One Belt and One Road”strategy,a large number of loess slopes have formed in the central and western regions of China,and the overburden in the loess slopes is in a non-saturated state all year round.Under unsaturated conditions,loess has complex soil and water characteristics and engineering characteristics.Rainfall can cause the change of matrix suction in unsaturated soils,in many cases,rainfall is the main factor that causes the deformation and damage of shallow unsaturated loess slopes and even induces instability.This article uses the loess high-filled slope formed by the ecological restoration demonstration project of the cement ash quarry in the Chuankou,Wangyi District,Tongchuan City,Shaanxi Province as the engineering background.Based on the experimental study on the soil water characteristics of high fill loess,the finite element method was used to study the non-saturated characteristics of fill loess and the stability of high fill slope under different conditions of rainfall infiltration.The main research work and achievements are as follows:(1)The soil-water characteristic curves of different particle grading samples were measured using the GCTS soil-water characteristic curve plot.The data of the soil-water characteristic curves obtained from the tests were fitted and analyzed through Matlab software,and the influence of different particle-level paired soil-water characteristic curves was studied.The mathematical model of soil-water characteristic curve suitable for the study sample was selected to study the influence of different parameter changes on the soil-water characteristic curve.(2)The wet-and-reducing cycle test was performed on samples with different particle gradations to study the hysteretic characteristics of the soil-water characteristic curves for different particle sizes.The results show that the smaller the particle size,the more obvious the hysteresis characteristics of the soil-water characteristic curve.(3)Taking a 2mm-diameter sample as an example,the Gardner empirical model and the Van Genuchten statistical conduction model were used to study the characteristics of the permeability coefficient curve of loess.The change regulation of the permeability coefficient of different models was obtained.(4)Abaqus finite element software was used to simulate the stability of the slope under rainfall conditions from rainfall duration,rainfall intensity,rainfall type,soil-water characteristic curve,and permeability coefficient.The stability of the slope under different rainfall conditions was studied and analyzed,The influence law of different rainfall elements on slope stability was obtained.