为研究砂粒对砂-粉土混合物强度特性的影响规律及作用机制,对不同含砂量的砂-粉土混合物进行三轴固结排水剪切试验和压汞试验。研究结果表明:随含砂量的增加,砂-粉土混合物的内摩擦角和峰值偏应力增大,黏聚力降低,含砂量≤30%时变化幅度最明显,其后较弱并趋于稳定;同时,峰值偏应力增幅随着围压的增加而增大。含砂量＜15%时,砂-粉土混合物的强度由黏聚强度控制,随着含砂量增大,摩擦强度逐步超过黏聚强度对强度起主要作用。砂-粉土混合物的体积收缩致使土体更加密实,从而导致砂-粉土混合物内摩擦角和峰值偏应力的增加。
Abstract
The aim of this study is to explore the influence of sand content on strength characteristics of sand-silt mixtures. To this end, triaxial consolidated drained shear tests and MIP tests were conducted on sand-silt mixtures with varied sand content. Test results indicate that as sand content increases, both the internal friction angle and peak deviatoric stress of sand-silt mixture increase while cohesion decreases. Such changes were more pronounced when sand content is below 30%, and then weakens and tends to stabilize. The increment of peak deviatoric stress raises as the confining pressure increases. When sand content is less than 15%, the strength of sand-silt mixture is controlled by cohesive strength. As sand content increases, the role of frictional strength gradually surpasses that of cohesive strength in influencing the overall strength. The volume shrinkage of the sand-silt mixture leads to a denser soil structure, resulting in an increase in the internal friction angle and peak deviatoric stress.
关键词
砂-粉土混合物 /
含砂量 /
峰值偏应力 /
压汞试验 /
微观机制 /
强度特性
Key words
sand-silt mixture /
sand content /
peak deviatoric stress /
MIP test /
micro-mechanism /
strength property
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基金
国家自然科学基金项目(41962016);教育部博士点基金项目(20136401110003);宁夏高等学校一流学科建设项目(NXYLXK2017A03)
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