Reliability Analysis For Slope Stability In Spatially Variable Soil

Slope stability has always been one of the research hotspots in the field of geotechnical engineering.Slope stability provides theoretical basis and engineering reference for slope construction risk removal and reinforcement.In the evaluation of slope stability,the soil is usually considered as a homogeneous material,and the safety factor of the slope is calculated by deterministic analysis.It is also used to evaluate the stability of the slope.Because of the influence of material composition,sedimentation history,consolidation pressure and other factors,the soil strength parameters have spatial variability.It is not accurate to use the safety factor to quantitatively describe the stability of the slope.In order to evaluate the reliability objectively,we could use safety factor and failure probability complementary.Due to the calculation efficiency is low,It limits its popularization and application in slope engineering.This article uses IPSO to calculate the safety factor of slope in slope reliability analysis,and the main contents and results are as follows:(1)Compared with traditional entry and exit method,The number of slip surfaces for PSO is 62.5%of the entry and exit method,and the number of slip surfaces for IPSO is 7.6%of the entry and exit method.PSO and IPSO can search for more dangerous slip surfaces,can obtain greater probability failure,and calculate higher accuracy.Compared with the PSO and IPSO,the average safety factor calculated by the IPSO is slightly larger,and the PSO can obtain a more accurate probability failure,PSO is only less than 1%higher than the failure probability calculated by IPSO.However,the calculation results are within the allowable error range,a the trial slip surface of IPSO is only 12.3%of PSO,IPSO has better calculation efficiency.(2)The random field was used to simulate the spatial variability of soil parameters.the influence of soil parameters(c/φ),soil spatial variability(COVc、COVφ、ρ(c,φ)、Lh、Lv)and geometric parameters(H、β)on slope reliability was studied.Tt is obtained under the same conditions of soil parameters(c、φ),slope height(H)and slope angle(β),Pf increases with the increase of COVc、COVφ、ρ(c,φ)、Lh and Lv,Fs μμdecreases with the increase of COVc、COVφ、ρ(c,φ)、Lh and Lv.When the soil parameters、soil spatial variability remain unchanged,Pf increases with the increase of H and β,Fsμ decreases with the increase of H and β.With the increasing H and β,the Pf and Fsμ changed gradually,and the influence on slope stability became more and more significant.When considering the influence of soil parameters on the reliability of slope,with the continuous increase of c and φ,the Pfgradually decreases,and the Fsμ gradually increases.(3)For Chicago Congress Street cut,the influence of it on slope reliability under seismic force was analyzed,The results show that seismic force has a great influence on slope stability.As the Horizontal quasi-static coefficient Kh increases,the Fsμ gradually decreases,and the Pf gradually increases.Under the action of seismic vibration,the failure probability of the slope increases with the increase of the correlated length.