Experimental Study on Structural Characteristic of Unsaturated Loess under Triaxial Shear

To study the structural properties of undisturbed loess,a series of triaxial shear tests of loess were done on the condition of suction control,including the stress-strain curves of undisturbed and disturbed loess,and the regularity for change of the structural strength qs of undisturbed loess.The test results show that the failure model of disturbed loess and undisturbed loess with controlled suction equaling 50kPa is shown with plastic failure;but the failure model of undisturbed loess with controlled suctions equaling 100kPa,200kPa is displayed with brittle failure.On the condition of triaxial shear,the developing curve of structural strength with loess has three-stage,the instantaneous structural strength τe is the peak when the axial strain e1 equaling about 2%,and that is defined as the structural strength qs of undisturbed loess.The water content w is a main factor affecting the structural properties of loess and suction s is an important stress variable about unsaturated soil.The relationship between structural strength qs and water content w,as well as structural strength qs and suction s has been set up by using the fitting of mathematical function.