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In cold regions, the strength of soil-rock mixture (SRM) is gradually reduced by freeze-thaw (F-T) cycles, in order to study the deterioration mechanism of mechanical properties of SRM under F-T cycles, indoor triaxial tests were carried out by taking into account the effects of the number of F-T cycles, the rock content and the confining pressure, and combined with the numerical simulation of particle discrete elements to analyze the microscopic deformation of the failure characteristics of the SRM, as well as the development law of the shear surfaces and the contact force chain. The results showed that the F-T cycle did not have much effect on the stress-strain curve morphology, but the peak and initial slope of the stress-strain curve increased with the increase of the rock content. The F-T cycle has a more obvious deterioration effect on the failure strength, elastic modulus and cohesion of the samples, but has less effect on the internal friction angle. The failure strength and elastic modulus of the samples increased with the increase of the confining pressure. With the increase of rock content, the failure strength, elastic modulus and internal friction angle of the samples increased, but the cohesion decreased. Under the flexible loading condition, the SRM samples exhibit swell failure, and the shear zone formed after failure is roughly distributed in an X shape, and the failure morphology of the SRM samples, as well as the morphology and size of the shear zone, are all affected by the rock content and the confining pressure. The contact force between particles in the SRM samples increases with the increase of rock content, and the chain of coarse force is mainly distributed in the vicinity of rock particles, but the F-T cycle will weaken the contact force between particles, thus reducing the strength of the SRM.

来源平台：GEOTECHNICAL AND GEOLOGICAL ENGINEERING