Study On Residual Strength Characteristics Of Malan Loess Under Different Water Content And Shear Rate

Loess is a Quaternary sediment that is widely distributed globally and concentrated in the mid-latitudes.China's loess has a good distribution continuity,wide area and large thickness.With the deepening of the development of the central and western regions,the Loess Plateau is the core area for the construction of the new Silk Road economic belt.The infrastructure construction has increased year by year,causing many geological disasters in the construction of the project.The increasing number of engineering activities has led to the resurrection of a large number of ancient landslides,causing huge losses to the lives and property of the people.Many studies have shown that residual strength is an important parameter for studying the mechanism of ancient landslide reactivation,and it is of great significance for slope stability.Based on the existing research results,the original undisturbed Malan loess at 7m underground depth is taken as the research object.Through the ring shear test,the residual strength characteristics of undisturbed Malan loess with different water content and shear rate were studied.The following research results were obtained:(1)Under the condition of normal stress is 100 kPa and shear rate of 0.1 mm/min,the moisture content of the sample increases from 0% to 10%,the residual strength gradually increases,and the peak strength gradually decreases;When it exceeds 10%,both the residual strength and the peak strength decrease as the water content increases.(2)The relationship between shear stress and shear displacement of different water content shows that with the increase of water content,the failure characteristics of the sample change from strain softening to strain hardening,and the failure mode changes from brittle failure to plastic failure.(3)The normal stress is 100 kPa,the moisture content of the sample is 15%,and the shear rate is set to 0.05,0.08,0.1,0.2,2,20 mm/min,respectively.Studies have shown that as the shear rate increases,the original state The residual strength and peak strength of Malan loess increased logarithmically.(4)Under low shear rate conditions,the shear surface is rougher and the number of layers is more.Under high shear rate conditions,the shear surface is smoother,and soil particles and water are discharged at the shear joint.An increase in the shear rate results in an increase in the thickness of the shear band.It can be seen from the failure mode of the sample that the shear rate affects the roughness and water content at the shear plane of the sample to some extent.