含水率对土石混合体力学特性影响的试验研究

摘要

土石混合体的变形和剪切强度参数主要受含石率、块石形状、土体性质和水等因素的影响，现阶段的研究主要集中在前3方面因素，少有考虑水对其力学性能的影响。本文通过采用卵石、粉质黏土和水的不同比例制备混合体重塑试样，开展室内大型直剪试验。研究结果表明：随着模型剪切位移增加，土石混合体应力－切向位移关系曲线表现出3个阶段：线性变形阶段、初始屈服阶段、硬化阶段。含石率和含水率共同作用影响土石混合体材料力学性质。其中土石混合体的抗剪强度随含水率的增加经历了缓慢减小－快速减小－缓慢减小3个过程；当含石率相同时，内摩擦角随着含水率的增加，经历了两个阶段的下降过程：低含水率的缓慢下降和高含水率的快速下降。%The deformation and shear strength parameters of soil-rock mixtures are mainly affected by the stone content,stone shape,nature of soil and water.Nowadays,the study mainly focuses on the three former aspects.The effect of water on the mechanical properties is rarely studied.This paper uses the pebbles,silty clay and water to make soil-rock mixture samples and carrys out large-scale direct shear tests.The test results show that as the shear displacement of model increases,the shear stress-displacement curve of soil-rock mixtures can be divided into three stages:linear deformation stage,initial yielding stage and hardening stage.The interaction of ratio of water and ratio of pebbles affects the mechanical properties of soil-rock mixtures.Overall,the shear strength of mixtures decreases as water content increases.The trend of decrease is slow at first,and then becomes rapid,and slow down again.For the same rock content,the internal frictional angle experiences two stages of decline process as the water content increases.Firstly,it decreases slowly when the water content is low.Then it decrease rapidly when the water content is high.