Study On Sliding Mechanism Of The High-Speed Railway Cutting Slope In Cold Regions Under Rainfall And Snow Melting Infiltration

Since the water content and pore water pressure in shallow layers are deep affected by melting snow and rain,the safety performance of the slope is hard to be estimated.At present,there are few literatures review the patterns between the pore pressure and water infiltration,also the mechanism between increased pressure and slide slope.With the support of National Natural Science Foundation of China,adopting thaw-consolidation theory,the analytical solution of the excess pore water pressure of the slope soil under infiltration conditions is obtained.Then proposed a slope sliding velocity model to calculate the speed of soil corresponding with water pressure.Finally,based on the proposed model,the numerical simulation of slope instability process in cold region is carried out according to practical engineering conditions.First,according to heat conduction and consolidation equations of the frozeeing-thawing area,the patterns of pore water pressure change during and after the thawing stabilization under the conditions of rainfall and snowmelting infiltration are obtained.The model calculation results show that the excess pore water pressure in the soil is composed of the soil consolidation and the pore water pressure generated by infiltration under the infiltration.The former increases linearly,while the latter increases nonlinearly with depth.When the thaw depth,ratio of infiltration amount and permeability coefficient increases,the pore water pressure in the soil increases.The thaw-consolidation ratio also increases with the ambient temperature increases,and the excess pore water pressure in the soil accumulates rapidly.Therefore,sunny slopes are more prone to landslip hazards than shady slopes.Second,based on the thawing consolidation theory and sliding consolidation model,considering the dilatation shear of the basal shear zone,analytical solutions of pore pressure and soil movement velocity during soil thaw-consolidation and shearing are presented.With that results,a landslide motion model in cold region considering infiltration and base shear was established.The model proposes that the slope will creep along with the slope direction during the thawing period,and permeability coefficient,dilatation angle,thaw-consolidation ratio,consolidation coefficient,melting depth,and the ratio of infiltration amount and permeability coefficient have an impact on the soil moving velocity.Under different boundary temperature and infiltrations,COMSOL Multiphysics is used to invesitgate the law of soil moving velocity during the spring thaw period.Combined with the soil slip velocity model and the "Saito method",the process to predict deformation of the high-speed railway cutting slope in the cold region is initially proposed.Finally,COMSOL Multiphysics is used to establish the slope Hydro-thermal coupling model.Within the region of shear strength theory of unsaturated soil and frozen soil,the regulation and safety factor of the slope melting rate during the spring thaw period are calculated,and the saturation and temperature are introduced as variables.The effects of ambient temperature conditions,the intensity of infiltration and freeze-thaw cycle on the temperature field and safety factor of the high-speed railway cutting slope in cold regions are also analyzed,to provide a more precise perspective for practical engineering.This thesis includes 47 figures,6 tables and 127 references.