Experimental Study of Triaxial Test of Unsaturated Expansive Soil Shear Strength

Based on unsaturated triaxial testing system,with different water content,the strength characteristics of expansive soils of Nanning are studied.Under certain confining pressure,with low water content,stress-strain curve is strain-softening,whereas with high water content,is strain hardening;Under high confining pressure,with low water content stress-strain curve is strain-hardening type,whereas with low confining pressure the stress-strain curve with the increase of axial strain is a slight softening trend.The shear strength of soil has a large sensitivity with moisture content.As the moisture content increases,the expansive soil friction angle decreases linearly.With the increase of water content,firstly its cohesive force increases,it reaches maximum value at the optimum water content,then it decreases with the increase of water content.