Particle size effects in soil-rock mixtures: a large-scale triaxial investigation
ZHANG Pei1, ZOU Changsheng1, YANG Jie2, HOU Shiwei3*, DU Xiuli4
(1. School of Civil and Transportation Engineering, Beijing University of Civil Engineering and Architecture, Beijing 102616, China; 2. College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, Guangzhou 518060, China; 3. School
of Civil Engineering, Shenyang Jianzhu University, Shenyang, Liaoning 110168; 4. Key Lab of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing 100124, China)
Abstract：Rock size is a critical factor influencing the macro-meso mechanical properties of soil-rock mixtures (SRM). To investigate the effect of particle size, this study conducted large-scale triaxial shear tests on SRM using the GDS apparatus, maintaining a constant relative density. Tests were performed on SRM with six different rock sizes under three confining pressures. The results indicate that the stress-strain behavior of SRM primarily exhibits strain softening. The variation of shear strength and initial elastic modulus with respect to Rd (the ratio of specimen diameter to the maximum particle size) can all be described by a power function. Rd = 10 is identified as the critical ratio; when Rd≥ 10.0, both the shear strength and strength parameters stabilize. The failure mode of SRM is jointly influenced by Rd and confining pressure. At a confining pressure of 100 kPa, the failure mode is characterized by shear failure. At 200 kPa, the failure mode transitions from shear failure to bulging failure as Rd increases. At a confining pressure of 400 kPa, the failure mode manifests as bulging failure. Under the same confining pressure, the particle breakage ratio follows a decreasing power-law trend with increasing Rd. These research findings are significant for accurately predicting the macroscopic mechanical properties of SRM.
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2026, Vol. 45 
