砂卵石土粗粒含量对基坑及隧道围岩等稳定性影响较大, 然而不同粗粒含量砂卵石土宏细观力学特性尚不明确.采用室内大型粗粒土三轴试验与数值三轴试验相结合的方法, 对不同粗粒含量砂卵石土宏观及细观力学特性开展研究.研究结果表明:随着粗粒含量增加, 砂卵石土的应力应变曲线表现为应变软化性;围压不变时, 砂卵石土随着粗粒含量增加, 应力峰值增大而达到峰值时的应变逐渐减小.建立了砂卵石土粗粒含量与内摩擦角和黏聚力等力学指标之间函数关系, 随着粗粒含量的增加, 砂卵石土的内摩擦角与黏聚力也以线性趋势增大;提出了不同粗粒含量砂卵石土的接触模量、颗粒刚度比、摩擦系数、接触粘结强度等颗粒离散元细观参数.研究成果为砂卵石地层工程精细化设计及施工提供理论支撑.%The coarse-grained content of sandy cobbled soil has a great influence on the stability of the foundation pit and tunnel surrounding rock, but the macroscopic and micromechanical properties of sand and gravel with different coarse contents are not clear. The macroscopic and meso-mechanical properties of different coarse-grained sand-pebbled soils were studied using a combination of a large-scale coarse-grained soil triaxial test and a numerical triaxial test. Research indicates that with the increase of coarse-grain content, the stress-strain curve of sand-pebble soil shows strain softening. When the confining pressure is constant, the sand pebble soil increases with the increase of coarse grain content, and the stress peak value increases, and the strain at the peak value gradually decreases. The functional relationship between the coarse-grained content and the internal friction angle and cohesion of sand-pebble soil was established. With the increase of coarse-grain content, the internal friction angle and cohesion of sand-pebble soil increased linearly; the parameters such as the contact modulus, friction coefficient, particle stiffness ratio, and contact bonding strength of different coarse-grained sand-pebble soils were proposed. The research results provide theoretical support for the refinement design and construction of sand and gravel strata.
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