融雪条件下新疆伊犁谷地黄土-卵砾石接触面残余强度

为研究融雪作用下黄土-卵砾石接触面残余强度，以新疆伊犁谷地某黄土-卵砾石接触面滑坡为例，通过自制模具，制作黄土-卵砾石接触面环剪试样，开展不同含水率黄土-卵砾石接触面环剪试验，并通过扫描电镜（SEM），从微观结构角度探究水对黄土-卵砾石接触面残余强度的影响。试验结果表明:黄土-卵砾石接触面抗剪强度随着含水率的增加而减小，剪切过程中存在应变软化现象，随着正应力及含水量的增加，应变软化现象越不明显；黄土-卵砾石接触面残余强度随着法向应力的增大而增大，且存在较好的线性关系，符合摩尔库伦强度准则；黄土-卵砾石接触面残余强度参数随着含水率的增加而降低，以含水率w=18%为界（塑限含水率19.1%附近），当含水率为10%~18%时，残余内摩擦角φ_r变化较小（Δφ_r=5.4°），当含水率为18%~26%时，残余内摩擦角φ_r变化较大（Δφ_r=9.0°）；微观结构方面，随着含水率的增加，黄土-卵砾石接触面形成软化"泥膜"，部分填充了卵砾石凹凸部分，剪切面较为光滑，在剪切过程中，黏粒更加分散，附着在黄土颗粒表面，部分填充孔隙，起润滑作用，降低了残余强度。本文的研究成果可以为新疆伊犁谷地黄土-卵砾石接触面型滑坡形成机理研究及工程防治提供科学参考。 

Residual strength of loess-gravel interface under snowmelt in Ili valley,Xinjiang

In order to study the residual strength of the loess-gravel interface, this paper investigated the residual strength of the loess-gravel interface with different water content by improved ring shear tests, what's more, the scanning electron microscopy (SEM) was taken to study the microstructure of the loess-gravel interface.The results show that residual strength of the loess- gravel interface decreased with increasing of the water content, and strain softening occurred during tests.With the increase of normal stress and water content, the strain softening phenomenon became less obvious; The residual strength of the loess-gravel interface increased with the normal stress, and there was a good linear relationship, which met the Mohr-Coulomb strength criterion, The residual strength parameters of the loess-gravel interface decreased with water content increasing.There was a critical water content w=18% (near the plastic limit water content 19.1%), when the water content ranged from 10%-18%, the residual friction angle φ_r changed slightly (Δφ_r=5.4 °).Respectively, when the water content ranged from 18%-26%, the residual friction angle φ_r changed greatly (Δφ_r=9.0 °).In terms of microstructure, with the water content increasing, the soft "mud film" was formed on the loess-gravel interface and partially filled with uneven surface.Thus the shearing surface was smooth.Meanwhile, during the shearing process, the clay was dispersed and absorbed to the surface of the loess particles and partially filled the pores which lubricated the loess particles and reduced the residual strength.The research results of this paper could provide scientific reference for the formation mechanism and engineering protection of loess-gravel interface landslide in Ili Valley.