Abstract
Interstitial liquid between particles is a significant factor affecting the shear characteristics of geotechnical granular materials. To further investigate this issue, this study systematically conducted ring shear tests on quartz sand of different saturations and particle sizes to study the effects of interstitial fluid on the effective friction coefficient, system fluctuations, volume strain, and particle breakage. It was found that the impact of saturation on the shear characteristics of quartz sand has a strong correlation with particle size. The effective friction coefficient of coarse sand shows a trend of increasing and then decreasing with increasing saturation. In contrast, the effective friction coefficient and system fluctuations of medium and fine sands are not sensitive to changes in saturation. The volume strain changes of quartz sand during shearing can be divided into three stages, with the trend in each stage significantly affected by saturation and particle size. The absolute crushing rate of coarse sand gradually decreases with increasing saturation. The smaller the particle size, the lower the likelihood of breakage. The impact of saturation on the absolute breakage rate of finer particles is not significant. Based on the results analysis, the interstitial liquid has an undeniable effect on the shear characteristics of geotechnical granular materials. The findings provide a scientific basis for further understanding the dynamic mechanisms behind the shear deformation and failure-induced disasters of geotechnical granular materials.