接触面力学特性中相对尺度效应的试验研究

Effect of relative scale to mechanical characteristics of interface

利用DRS-I型高压直剪仪进行了砂砾与9种形貌相同、尺度不同(峰谷距不同)结构面的接触剪切试验,研究结构面峰谷距与砂土颗粒平均粒径之间的相对尺度(R=H/d50)对接触面力学与变形特性的影响.试验结果表明,结构面峰谷距与砂土平均粒径间的相对尺度R直接影响着接触面的力学与变形特性,存在"极限相对尺度"Rmax与"临界相对尺度"Rcr.在"极限相对尺度"之前,相对尺度R的增大使得接触面剪切强度与剪切体变随之呈近似线性增大趋势;"极限相对尺度"之后,接触面剪切强度与剪切体变随相对尺度的增大有一定程度的减小;在达到"临界相对尺度"之后,接触面剪切强度与剪切体变亦达到临界状态并随着相对尺度R的增大呈微小变化,变化幅值较小.

The interface shear test of gravel and 9 kinds of structural planes with the same mor phology are carried out by DRS-I high pressure direct shear apparatus. With these structural planes having 9 different peak-valley distances H, relative scale R is defined as the ratio of peak-valley distance to average particle size （R= H/d5o）. Effects of relative scale R to mechanical and deformation characteristics of interface are studied. The results show that the relative scale R affects the interface shear strength and deformation directly, and the R has limited and critical value which are described as Rmax and Rcr. Before R the increase of R results in linear increase of interface shear strength and deformation. After R the increase of R will cause interface shear strength and deformation having a certain degree of reduction. When the rela- tive Scale R reached to Rcr, interface shear strength and deformation also come to critical state and they will just meet slight changes with the increase of R. The Rmax and Rcr have a crucial influence for studying the interface mechanics and deformation mechanism of coarse-grained soil and rou^zh structural planes.