An experimental study on the effect of inter-particle friction on mechanical behavior of granular materials

Abstract

This paper describes an investigation into the effect of inter-particle friction on shear behavior of granular materials,by performing a series of direct shear tests on an analogous soil-glass bead.In this test study,four types of inter-particle friction conditions are concerned,including dry state,water-lubricated state,flooded state and oil-lubricated state.An analysis of the test results reveals that oil lubrication is able to significantly decrease dilatancy and shear strength of granular specimens,whereas the means of water lubrication and complete submergence in water do not exert a notable effect.Based on test results,a stress-dilatancy equation is proposed that is able to properly take into account the effect of inter-particle friction on the dilatancy of granular materials.The effect of inter-particle sliding friction angle on critical state friction angle is preliminarily examined from a perspective of microscopic particle motions,namely,particle sliding and rolling.

通過對一種類似于土的顆粒材料——玻璃珠開展一系列室內直剪試驗,研究顆粒間摩擦對顆粒材料剪切行為的影響.試驗一共考慮了4種不同的摩擦情況:干燥狀態、用水浸潤狀態、完全淹沒在水中和用油浸潤狀態.分析試驗結果發現,與干燥狀態試樣相比,用油浸潤能明顯降低試樣的剪脹性和抗剪強度,而用水浸潤和淹沒在水中的方法沒有產生顯著的影響.此外,通過在剪脹關系式中引入可變剪脹系數來考慮顆粒摩擦對顆粒材料剪脹性的影響,并從顆粒滑動與滾動的細觀機理上初步解釋了顆粒滑動摩擦角對臨界狀態摩擦角的影響規律.