Experimental study on plastic deformation of alluvial silty sand under traffic cyclic loading

With the development of highway construction, alluvial silt is gradually used as roadbed filler, but its dynamic characteristics are less studied. Based on the highway section from Luanzhou to Qingtuoying of G508, the plastic strain and dynamic stress-dynamic strain development law of alluvial silty sand under cyclic loading are analyzed by GDS dynamic triaxial test. The results show that under the action of a small range of dynamic stress amplitude, the soil sample is not destroyed, and the number of cycles is 1000 times, which is the critical point at which the axial total strain gradually tends to be stable. When the dynamic stress amplitude is 300 kPa, the total axial strain increases linearly, and the soil sample is destroyed. The cumulative plastic strain of the alluvial silt is the smallest when the optimum water content is 8.0 %, the confining pressure is 80 kPa, and the frequency is 1Hz.At this time, the cyclic load has a dense effect on the soil, and the soil structure does not fail. The dynamic stress-strain relationship of alluvial silty sand conforms to the R. L. Kondner hyperbolic model. The greater the confining pressure and the closer the moisture content to the optimal moisture content, the greater the dynamic strength. The research results are helpful to provide reference for other similar projects.