为了探索快速评价重金属污染红黏土强度特性的新型手段,在室内开展不同浓度、不同干密度的Cu2+污染红黏土的直剪试验及其电阻同步测试试验,得到土体剪应力、电阻率-剪切位移同步变化曲线;分析初始干密度、垂直压力、Cu2+浓度对抗剪强度、电阻率的影响;依照抗剪强度指标(C、φ)原理选取电阻率指标(ρ0、φ0),并分析Cu2+浓度对抗剪强度指标(C、φ)、电阻率指标(ρ0、φ0)的影响;以Cu2+浓度为中间变量,进一步探讨抗剪强度与破坏电阻率、抗剪强度指标(C、φ)与电阻率指标(ρ0、φ0)之间的定量关系。试验结果表明:Cu2+污染红黏土剪应力-位移曲线呈典型的应变硬化型,电阻率随剪切位移的增大而减小;抗剪强度随初始干密度、垂直压力的增大近似线性增大,而电阻率随初始干密度、垂直压力的增大近似线性减小;抗剪强度及其指标(C、φ)、电阻率及其指标(ρ0、φ0)与Cu2+浓度间均呈负指数函数关系;抗剪强度与破坏电阻率、黏聚力与初始电阻率、内摩擦角与电阻率关系曲线倾角间的变化趋势一致,均呈现出较好的指数函数关系,可用于快速评价Cu2+污染红黏土强度特性变化。
Abstract
The aim of this research is to explore a new method for evaluating the strength characteristic rapidly of heavy metal-contaminated red clay. Direct shear test and resistivity test were carried out for Cu2+ contaminated red clay specimens of varied concentration and dry density. The curves of shear stress and resistivity of Cu2+ contaminated red clay varying synchronously with shear displacement were obtained. Meanwhile, the impacts of initial dry density, vertical pressure, and Cu2+ concentration on shear strength and resistivity were analyzed. According to the principle of shear strength indexes (C and φ), resistivity indexes (ρ0 and φ0) were selected, and the effects of Cu2+ concentration on shear strength indexes and resistivity indexes were examined. Furthermore, the quantitative relations between shear strength (indexes) and destructive resistivity (indexes) were discussed. Test results unveiled that the shear stress-displacement curve of Cu2+ contaminated red clay displayed typical strain hardening features, while resistivity declined with the increase of shear displacement. Shear strength augmented approximately linearly with the growing of initial dry density and vertical pressure while destructive resistivity showed opposite trend. Both shear strength (indexes C and φ) and resistivity (indexes ρ0 and φ0) were in a negative exponential functional relation with Cu2+ concentration. In addition, the curve of shear strength vs. resistivity, curve of cohesion vs. initial resistivity, and curve of internal friction angle vs. inclination of resistivity relation curve displayed consistent trend, showing a good positive exponential function relationship.
关键词
红黏土 /
Cu2+污染 /
抗剪强度 /
黏聚力 /
内摩擦角 /
电阻率 /
重金属污染
Key words
red clay /
Cu2+ contamination /
shear strength /
cohesion /
internal friction /
resistivity /
heavy metal contamination
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基金
国家自然科学基金项目(41762022);桂林市科技开发项目(20170222);广西中青年教师基础能力提升项目(2018KY0239);广西科技计划项目(2017GXNSFBA198052)
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