Experimental Research On The Soil Water Characteristic Curve And Strength Character Of The Remolded Unsaturated Culluvial Clay

Study on the mechanics behavior and strength characteristics of the unsaturated culluvial soil becomes the most important problem in geotechnical engineering.Due to the complicated engineering properties and the imperfect theories of unsaturated soils,Slope collapse,debris flow and other disasters continue to be frequent,which gives the people's lives and property security a serious threat.In order to solve this problem,In this paper,the shear strength and soil water characteristic curve analysis of remolded unsaturated culluvial clay through a set of laboratory tests,and multiple groups of suction,saturation and dry density are also conducted respectively.the mechanical properties and strength characteristics of the remolded unsaturated culluvial clay were studied in system and depth,and the theoretical formulas of strength were established,which could provide reference for engineering practice.The results of this paper are as follows:(1)The research on the basic physical properties of the culluvial soil were conducted,and the basic physical indexes such as specific gravity,liquid limit,plastic limit,maximum dry density,optimum moisture content,nonuniformity coefficient and curvature coefficient were determined,And ultimately determine the culluvial soil for high liquid limit clay with the poor classification of sand-containing,code-named CHS.(2)The mathematical model of soil water characteristic curve was established,and the residual section of soil water characteristic curve was predicted by this model.The soil water characteristic curve was fitted with representative Gardner model,Van Genucheten model,Mckee and Bumb model.This paper analyzes the reliability and rationality of the mathematical model constructed in this paper.(3)Through the non-saturated strain control type direct shear test,it is found that the consolidation amount of the remolded unsaturated culluvial clay increases sharply with the application of the load,and finally stabilizes.The shear stress-strain curve is sheared and softened at lower stress.Under the high stress,the shear stress is shown as shear shear.The shear strength increases with the increase of matrix suction,and increases linearly at each stage.(4)On the basis of the above experiment,the shear strength formula of the remolded unsaturated culluvial clay is established.Among them,the higher the dry density,the higher the total stress shear strength of the remolded unsaturated culluvial clay.When the saturation from the saturated state to the residual state,the shear strength of the remolded unsaturated culluvial clay showed the first increase,then reduced,and ultimately stabilized.(5)The cohesive force of the remolded culluvial clay is from the saturated state to the residual state,which also shows increasing,decreasing and stabilizing.The variation law is similar to the normal distribution.With the saturation increasing,the internal friction angle shows a non-linear decrease.It was also found that the cohesion increased with the increase of the dry density,but the internal friction angle increased little with the increase of the dry density.