基于大型直剪试验的土石混合体颗粒破碎特征研究

发布时间：2018-03-03 16:37

本文选题：土石混合体　切入点：直剪试验　出处：《岩土工程学报》2017年08期 　论文类型：期刊论文

【摘要】：土石混合体剪切时存在细观上的颗粒破碎现象,并对其宏观力学性质产生影响。基于此,以4种含水率的土石混合体为研究对象,通过室内大型直剪试验和筛分试验,分析土石混合体剪切后的颗粒破碎特征,并建立细观颗粒破碎与宏观力学性质的联系,从而加深对宏观力学性质的认识。研究结果表明:土石混合体剪切后的颗粒破碎较明显,可分为完全剪断型、表面破裂型和表面研磨型3类;颗粒破碎细观上表现为粗粒组含量降低、细粒组含量增加、中等粒组含量波动变化,统计上表现为级配曲线上移,宏观上表现为低含水率出现应变软化破坏、高含水率出现应变硬化破坏、中等含水率出现塑性应变破坏、剪应力剪切位移曲线"跳跃"和强度非线性特征,本质上是颗粒间接触力作用产生应力集中的结果;颗粒相对破碎率随着含水率的降低或法向压力的增大而增大;黏聚力和内摩擦角均随着含水率的增大而呈幂函数规律降低。
[Abstract]:There exists the phenomenon of particle breakage in the soil and rock mixture during shear, which has an effect on its macroscopic mechanical properties. Based on this, four kinds of soil and rock mixtures with different moisture content are taken as the research object, and the large scale direct shear test and screening test are carried out in the laboratory. The characteristics of particle breakage after shear of soil-rock mixture are analyzed, and the relationship between micro-particle breakage and macroscopic mechanical properties is established, so as to deepen the understanding of macroscopic mechanical properties. The results show that the particle breakage of soil-rock mixture after shear is obvious. It can be divided into three types: complete shearing type, surface rupture type and surface grinding type, the content of coarse grains decreases, the content of fine grains increases, the content of medium grains fluctuates, and the gradation curve moves up statistically, the content of coarse grains decreases, the content of fine grains increases, the content of medium grains fluctuates, and the statistics shows that the gradation curve is upward. Macroscopically, there are strain softening failure in low moisture content, strain hardening failure in high moisture content, plastic strain failure in medium moisture content, "jump" in shear stress and shear displacement curve and nonlinear strength. In essence, it is the result of stress concentration caused by contact force between particles; the relative breaking rate of particles increases with the decrease of water content or the increase of normal pressure; the cohesion force and the angle of internal friction decrease with the increase of water content, and the law of power function decreases.
【作者单位】：重庆大学土木工程学院;山地城镇建设与新技术教育部重点实验室(重庆大学);中铁重庆地铁建设指挥部;
【基金】：国家自然科学基金项目(41372356) 高等学校博士学科点专项科研基金项目(20110191120033) 中央高校基本科研业务费科研专项自然科学类项目(CDJZR12200012)
【分类号】：TU43

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