三峡库区藕塘滑坡滑带土抗拉与抗剪强度关联机制OA

Variations in the moisture content of sliding zone soils,resulting from rainfall and rising groundwater levels,significantly contribute to the reduction of shear strength and the stability of landslides.This study investigates the strength characteristics of sliding zone soils under different moisture conditions by analyzing soil samples collected from the sliding zone of the Outang landslide in the Three Gorges Reservoir area.Various methods,including a pressure plate apparatus,salt solution humidity control,and dual-component air humidity control,were employed to prepare soil samples with low,medium,and high suction states.A multifunctional testing device for unsaturated soils was utilized to measure the tensile and shear strength of these soil samples under varying matrix suction conditions.The results indicate that the low-suction sliding zone soils exhibit ductile behavior during both tensile and shear processes,whereas the medium-to high-suction soils demonstrate brittle failure.Trends in uniaxial tensile and shear strength closely resemble those of matrix suction,exhibiting a non-linear monotonic increase as moisture content decreases.Notably,at a matrix suction of 221.6 MPa,the tensile and shear strengths reach 279.8 and 204.9 kPa,respectively.Even when fully saturated,the tensile and shear strength values remain at 46.0 and 32.3 kPa,respectively.The correlation between the tensile and shear strengths of sliding zone soils can be accurately described using an extended Mohr-Coulomb strength criterion based on suction stress theory.The predicted shear strength values calculated by suction stress theory and uniaxial tensile strength tested under various matrix suction conditions align closely with the experimental results.This methodological approach offers a significant reduction in both the time and costs associated with testing and calculating the shear strength of unsaturated sliding zone soils across different moisture states.