Study on the mechanical properties of coarse-grained soils with different fine-grained contents under freeze-thaw cycles

Abstract

This research analyzed the impact of fine-grained content on the mechanical characteristics of coarse-grained soil in the river valley region of southeastern Xizang under freeze-thaw cycle circumstances via indoor tests, and modified the Duncan-Zhang model based on the test results. A total of six different coarse-grained soil samples with different concentrations of tiny particles (Those particles that have a particle size of less than 0.075 millimeters are referred to as fine grains), ranging from 0% to 10%, were set up for the experiment. The stress-strain relationship, shear strength, and the variable patterns of its strength parameters were the primary areas of focus among the systematic triaxial shear tests that were carried out. Based on the findings, it can be seen that the shear strength, cohesiveness, and internal friction angle of coarse-grained soil steadily decrease as the frequency of freeze-thaw cycles rises. Nevertheless, the pace of decline progressively slows down with the rise in the number of cycles, and for the most part, it stays steady after ten cycles have passed. Furthermore, the kind of deformation that occurs in the soil, as well as the features of its strength, are significantly impacted by the amount of tiny particles that are present. When the percentage of fine particles in the mixture is 4%, the shear strength and cohesion are at their lowest possible values. However, when the percentage of fine particles is increased to 8%, both of these values are at their highest possible levels. Meanwhile, there is a possibility that the mechanical characteristics of the soil might be greatly improved by increasing the confining pressure. Based on the above experiments, the Duncan-Zhang model was modified.