Study On The Sliding Mechanism Of Q₂ Paleosol At The South Bank Of Jing River

The landslide disaster in the south bank of the Jing river is extremely serious,and it's caused enormous economic and property losses.The slopes include the loess and the paleosol layer,and the boundary surface often has a stronger control effect on the sliding surface of the landslide.Research to understanding the mechanics characteristics of paleosol is very necessary.It can help us to better understand the formation and control mechanism of loess landslide.and enrich the theoretical basis of the loess landslide study,deepen the loess landslide deformation mechanism and research the paleosol sliding mechanism.At the same time,the research of the paleosol will provide theoretical basis for prevention and control of the loess landslide.This article takes Zhaitou landslide as the research object,and the purpose is the sliding mechanism of paleosol,through on-site investigation,this article analyzes the development regularities,forming condition and distribution law of loess landslide.In addition,by laboratory test and quantitative analysis,the specific landslide control mechanism of paleosol in loess landslide can be be better described.According to the systematic study,the research work and conclusions are listed as follows:The undrained triaxial consolidation tests on loess and paleosol were conducted.The results show that the destruction types of the loess and paleosol can be divided as ideal plastic deformation under the low confining pressure.The samples bulges and axially shortens without obvious shear fracture.The stress-strain curve belongs to strain softening,obvious tress drop appears after the presence of peak value,which occurs in the presence of high confining pressure of loess.But the stress-strain curve of the paleosol belongs to strain hardening,and no peak value.In the saturated condition,the shear strength of the loess and paleosol was significantly reduced,and the strain softening of the loess was obvious.With the change of moisture content,the effective internal friction Angel of the paleosol varies very little,and the relationship of the effective cohesion and moisture content are curvilinear.Using shear test data of the loess and paleosol,this article established Duncan model under the condition of natural and saturated.The result shows that the applicability of the model has some limitations.It can describe the strain hardening of the paleosol,but the strain softening of the loess has certain limitations.The results of the triaxial penetration test shows that the permeability coefficient of the paleosol is less than that of the loess.The permeability coefficient was reduced with the increase of the confiding pressure,and under the low confining pressure,the permeability coefficient shows a liner decline.The vertical permeability coefficeitn were greater than that of horizontal for the loess and paleosol,and it's more obvious under the condition of low confining pressure.The failure mode of the loess landslides in Jing river can be divided into four stages,loess collapsibility,formation of crack?soil saturated,the crack development?soil liquefaction,crack penetrating?stage of stable.Four different condition landslide were simulating through the Midas –GTS,and we can analyse the change of stress and strain,then verify the important influence of the paleosol as aquiclude for the landslide during irrigation.Based on different conditions of horizontal displacement,vertical displacement,maximum shear strain and displacement vector cloud,the maximum shear stress appears near the loess and paleosol interface in the slope toe,the vertical displacement is also developed,and it can cause the formation of tensile fracture.The uplift of the slope toe is consistent with the actual investigation With saturated loess layer gradually thickened by the accumulation of irrigation water,the displacement and maximum shear strain increased and the slope is more stability.