Experimental study on the influences of content of fine particles on mechanical properties of typical coarse-grained mixed soil in Xinjiang

Coarse-grained mixed soil exists widely in the diluvial area in front of mountains in Xinjiang, and collapse deformation is easily induced to cause engineering diseases when encountering water. A series of triaxial tests are carried out on the typical coarse-grained mixed soil in Turpan area in order to determine the evolution of mechanical properties of coarse-grained mixed soil with the content of fine particles. The results show that: (1) With the increase of the content of fine particles, the peak partial stress of the typical coarse-grained mixed soils decreases, and the stress-strain curve gradually changes from strain softening to strain hardening. (2) The internal friction angle and cohesion of mixed soil decreased with the increase of the content of fine particles, while the attenuation rate of cohesion is higher than that of internal friction angle. (3) After consolidation, the pore ratio of mixed soil decreases with the increase of the content of fine particles, but the maximum dry density increases instead, resulting in the decrease of the relative compactness. 4) The evolution of bulk strain of all soil samples exhibits shear shrinkage followed by shear expansion, and the shear shrinkage increases with the increase of the content of fine particles and confining pressure. The influence of confining pressure on the bulk strain is more significant under higher content of fine particles. The research results provide an effective reference for further determination of the mechanical properties of typical coarse-grained mixed soils in different initial states in Xinjiang.