Study On The Characteristics Of Deformation And Water Permeability As Well As Soil Water Characteristics During Wetting For Loess Under The Condition Of Confining And Triaxial Stress

Loess is a kind of Quaternary sediments. which is widely distributed in Our country: Due to the water sensitivity. porosity, structure and so on caused by the strong collapsibility, under the action of force and weater,the strength of soil will decrease suddenly and the deformation will increase greatly. In practical engineering, the soil is often in unsaturated slate, The change of climate, natural environment and human factors will change the water content of soil, So that the strength and deformation of the soil change, endangering the safety of Engineering construction. Therefore, under different stress conditions, it is of great theoretical and practical significance to study the deformation characteristics, soil water characteristics and seepage charateristics of the undisturbed unsaturated loess under wet conditions.In this paper, a series of protgressive wetting tests on undisturbed unsaturated loess under triaxial stress conditions are earried out, The influences of shear stress level and net mean stress on the wetting strain (wetted bulk strain, moistening axial strain)and water content and suction loss are analyzrd,The expression of the relation between the strain ratio (the ratio of the prior strain to the total strain) and the suction loss is described; Analysis of the shear stress level and net mean stress on soil watcr characteristic when the humidification (saturation and suction,water content and suction relationship) and seepage characteristics (water permeability and saturation,permeability coefficient and suction effect relationship), Under different stress conditions, the saturation water content ratio (ratio of water content and saturated uater content)and suction ratio (the ratio of suction and degassing value), saturation and suction ratio and relative permeability cocfficient(the ratio of permeabiity coefficient and saturated permeability coefficient of the relanonship can be normalized). The expressions of soil water characteristics and seepage characteristics, of undisturbed loess under the action of stress are established.For remolded loess, unconfined compressive strenfth test,K0 consolidation test that can measure latal stress and graded humidification test under different side stress conditions are carried out Througo the unconfined compression strength test, the ralationship between theinitial structural paranmeters and the coefficient of the static earth pressure is established Based on the K0 consoliation test ,the effect of dry density,water content , stress and loading and unloading paths on compression, collapsibility and coefficient of static earth pressure are analyzed, A normalized expression of the ratio of void ratio to initial void ratio and stress ratio(ratio of stress to yield stress) is presented to describe the relationship between void ratio and initial void ratio at different dry densities and different moisture content, The coefficient of static earth pressure of normally consolidated soil under different conditions is determined, and the parameters of the static soil pressure coefficient of unloading and reloading are calculated.By comparing the coefficient of collapsibility between single line method and double line method, it is found that the force and water path have a great influence on the coefficient of collapsibility, and the coefficient of collapsibility of single line method is smaller than that of double line method.