HUANG Haijun,MAO Haitao,YAN Xinjun,et al.Water Sensitivity Characteristics of Shear Strength of Purple Soil in High Slope of Three Gorges Reservoir Area[J].Journal of Disaster Prevention and Mitigation Engineering,2020,40(06):974-983.
HUANG Haijun,MAO Haitao,YAN Xinjun,et al.Water Sensitivity Characteristics of Shear Strength of Purple Soil in High Slope of Three Gorges Reservoir Area[J].Journal of Disaster Prevention and Mitigation Engineering,2020,40(06):974-983. DOI: 10.13409/j.cnki.jdpme.2020.06.017.
Water Sensitivity Characteristics of Shear Strength of Purple Soil in High Slope of Three Gorges Reservoir Area
Purple soil is widely distributed in the Three Gorges Reservoir area, and the purple soil on the high slope is easy to be eroded and likely to slide. In order to study the variation of shear strength and deformation of purple soil with water content on high slopes, consolidated undrained triaxial tests were carried out on unsaturated remolded purple soil specimens with different water contents under different confining pressures. The results showed that under different water content and confining pressure conditions, the stress-strain curves of soils exhibit the phenomenon of “continuous hardening” or even “accelerated hardening”. The stress-strain relationship curve undergoes three stages: elastic stage with an axial strain interval of 0%~2.3%, strain hardening stage with an axial strain interval of 2.3%~4% , and yield stage with axial strain larger than 4%. Under the same confining pressure, the peak value of soil principal stress decreases with the increase of water content, and the peak value decreases by up to 67.37%; the maximum principal stress difference and confining pressure show a good linear relationship under different water contents. At a given water content, the peak value of principal stress difference increases obviously with the increase of confining pressure, and the maximum increment is about150.98%. However, with the increase of water content, the increasing trend decreases gradually, and the effect of confining pressure on the shear strength of purple soil is about 66.63% of that of water content. With the increase of water content, the cohesion of soil increases first and then decreases, and the water content at the peak is 12%. The internal friction angle of soil shows a first-order linear decrease relationship with the increase of water content, and the degree of decline can reach up to 56.88%. The slope of the σ-τ curve on the arbitrary plane of the soil gradually decreases with the increase of water content, and the damage envelope plane appears to gradually slow down. The influence of water content on the internal structure, intergranular force and characteristics of purple soil is analyzed and discussed in order to provide theoretical and technical support for comprehensive treatment of purple soil on the high slope of Three Gorges Reservoir.
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