| 摘要: |
| 花岗岩残积土在我国东南沿海地区广泛分布，其力学特性对水极为敏感，并且所涉及的工况复杂。为探寻两者对花岗岩残积土强度特性的影响，采用全自动真三轴系统对不同含水率下的花岗岩残积砂质黏性土进行了轴对称三轴试验、平面应变试验和等σ3等b（中主应力系数b=(σ2-σ3)/(σ1-σ3)=0.25）的真三轴试验，研究了花岗岩残积砂质黏性土在三种典型应力路径条件下的强度特性、在平面应变条件下的中主应力系数，最后对比分析了三种应力路径下的破坏模式及真三轴试验后土体的微观结构。结果表明：相较于轴对称三轴试验，真三轴条件下花岗岩残积砂质黏性土的强度提高了1.14~2.02倍，平面应变条件下提高了1.12~1.95倍；低含水率低固结压力下土体易产生剪切带，应力-应变曲线均为软化型，随着固结压力升高，应力应变曲线向应变硬化型转变；黏聚力c对含水率更敏感，随含水率增大降幅显著，内摩擦角则上下波动；当含水率超过27%后，土体强度衰减趋于稳定；平面应变条件下破坏时的中主应力系数b介于0.16~0.24之间；花岗岩残积砂质黏性土的破坏模式可分为鼓胀破坏、单剪切破坏、“Y”型剪切破坏3类。 |
| 关键词: 真三轴试验 花岗岩残积土 应力路径 强度特性 破坏模式 |
| DOI： |
| 分类号:xxxxxx |
| 基金项目:国家自然科学基金地质联合基金重点支持项目(U2444220)；厦门市自然科学基金项目(3502Z202372047) |
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| Effects of moisture content and stress path on strength characteristics of granite residual soil |
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YAO Wei1, HE Kunrong1, YU Jin2, ZHOU Xianqi1, ZHAO Huali1
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1.School of Civil Engineering and Architecture,Xiamen University of Technology;2.Fujian Research Center for Tunneling and Urban Underground Space Engineering,Huaqiao University
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| Abstract: |
| Granite residual soil is widely distributed in the southeast coastal areas of China. Its mechanical characteristics are highly sensitive to water, and the involved working conditions are complex. To explore the impact of the two factors on the strength characteristics. Axial symmetric triaxial tests, plane strain tests and true triaxial tests in which both σ3 and b (The intermediate principal stress coefficient b=(σ2-σ3)/(σ1-σ3)=0.25) keep constant were conducted on granite residual sandy cohesive soil with different moisture contents by using a fully automatic true triaxial system. The strength characteristics of granite residual sandy cohesive soil under three typical stress paths and the median principal stress coefficient under plane strain were studied. Finally, the failure modes under the three stress paths and the microstructure of the soil after the true triaxial test were compared and analyzed. The results show that compared to axisymmetric triaxial tests, the strength of granite residual sandy cohesive soil increased by factors of 1.14 to 2.02 under true triaxial conditions and by 1.12 to 1.95 under plane strain conditions. At low moisture content and low consolidation pressure, the soil is prone to shear banding, and the stress-strain curves are all softening types. As the consolidation pressure increases, the stress-strain curves tend to strain harden. The cohesion c is more sensitive to moisture content and decreases significantly with the increase of moisture content, while the internal friction Angle fluctuates up and down. The infiltration of water mainly affects the cohesion of the soil mass. When the moisture content exceeds 27%, the strength attenuation of the soil tends to stabilize. The intermediate principal stress coefficient b at failure under plane strain conditions is between 0.16 and 0.24. The failure modes of granite residual sandy cohesive soil can be classified into three types: bulging failure, single shear failure, "Y"-shaped shear failure. |
| Key words: true triaxial test granite residual soil stress path strength characteristic failure modes |
