Study On The Mechanical Characteristics And Soil-Water Characteristics Of Loess Under Wetting And Loading

Loess is a typical unsaturated soil with significant water sensitivity.Based on modern unsaturated soil mechanics theories and methods,the effects of loess force and water action sequence on mechanical properties and the effect of hydraulic coupling on hydraulic properties are studied around water sensitivity.It is an important theory for seeking to solve water-related loess enginueerring problems Significance and practical value.Therefore,based on various types of laboratory tests,this paper studies the deformation,strength,permeability and soil-water characteristics of loess under wet load.Triaxial tests were carried out under two force paths:wet first,then load,and then wet then reload.The suction,force,water path,and eccentric compressive properties of humidified partial stress were analyzed,as well as the triaxial shear deformation strength and yield.And the influence of critical state characteristics,the relationship between the shear strength index and effective stress parameters χ,φb and suction is discussed;the change characteristics of saturation during isotropic compression and triaxial shear are analyzed to explore the isotropic compression stress The effect of the triaxial shear stress on the soil-water characteristic curve characterized by the relationship between saturation and suction reveals the changing law of soil-water characteristics during compression and shear humidification.Based on the normal isotropic compressive stress grading hunidification test of undisturbed loess,the relationship between humidification deformation and suction loss and water content is analyzed,and the relationship between the isotropic compressive stress and yield suction and humidification deformation characteristic indexes is obtained;The water holding characteristics characterized by the relationship between water content and suction,saturation and suction under stepped humidificalion under isotropic compressive strces conditions are analyzed,and the effect of isotropic compressive stress on the parameters of van Gcnuchten model is discussed;Based on the principle of combined measurement of water and gas,the seepage coefficient during humidification is determined,and it is revealed that the isotropic compressive stress has a significant effect on the relationship between the seepage cocfficient and the suction and saturation,and the relationship between the relative seepage coefficient and the suction ratio and saturation The effects are very small,and can be approximately described by the same humidification and seepage function.Based on the permeability test of undisturbed loess with different humidity under triaxial stress conditions,the effects of water content,isotropic compressive stress and triaxial shear stress on the relationship between gas permeability coefficient,saturation and volumetric gas content were analyzed and directly considered The gas permeability coefficient expressions of water content,confining pressure and shear stress level reveal that the gas permeability coefficient and corrected gas saturation and the relative gas permeability coefficient and saturation are approximately normalized under different isotropic compression and triaxial shear stress conditions relationship.In addition,for The remolded loess in Xian,Lanzhou,and Yili regions conducted gas permeability tests under triaxial stress conditions,discussed the permeabilily characteristics of remolded loess with different dry densities and water contents in the three regions,and analyzed the permeability cocfficient and triaxial stress,The relationship between saturation and volumetric gas content,comparatively studied the difference of gas permeability function parameters in different regions,and verified the suitability of the proposed gas permeability model considering the effect of hydraulic coupling for different regions of loess.