82 / 2019-07-30 21:58:31

Study on the change of soil pore structure and strength deterioration law of slip soil based on micro-macro parameters

Slip soil；Micro-macro parameter；Ring shear test；Pore structure；Strength deterioration law

水库地质灾害防治与生态环境保护 > 表生地质作用与地质灾害演化过程

Landslide disasters frequently occur in mountainous areas in southwestern China and reservoir areas affected by extreme rainfall climate and topography. In the process of landslide development, the deformation evolution and strength deterioration of the slip soil play an important role in the stability of the landslide. At present, the research on the micro-macro quantitative relationship of the slip soil and the strength variation characteristics of the slip soil remains to be further studied. In this paper, the viscous slip soil of a landslide in the southwest mountainous area was selected as the research object, and the ring shear test of the slip soil under different moisture contents and different shear rates was carried out to explore the peak strength and residual strength characteristics of the slip soil in the two conditions. At the same time, the pore structure and soil particle morphology of the slip zone soil were observed by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). The quantitative and qualitative methods were used to analyze the characteristics of the soil pore structure and the relationship between macroscopic and microscopic parameters. The results show that: The increase in moisture content will reduce the peak strength and residual strength of the slip soil. The increase of shear rate has a significant increase in the peak strength of the slip soil, but has little effect on the residual strength. The increase in moisture content causes the slip soil to exhibit a more pronounced strain softening characteristic during the shearing process, and the increase of the shear rate weakens the strain softening phenomenon. Higher moisture content and lower shear rate enable the slip soil to reach a residual strength state with a small shear displacement. The increase of moisture content and shear rate has significant correlation with the change of pore structure and soil particles during the deformation of slip soil, which is manifested by increased porosity and reduction of macropores. The shearing action makes the pores and soil particles long and narrow which shows obvious orientation characteristics and fractal characteristics. And the strength parameters of slip soil based on porosity and pore fractal dimension can better reflect the strength deterioration characteristics of slip soil under two conditions. The results of this paper can provide theoretical basis for the study of the formation mechanism of relevant landslides, and have practical significance for the prevention and control of landslides with similar influencing factors.