Strength characteristics and particle crushing analysis of gravel-block soil in the Yarlung Zangbo River valley of the Qinghai-Tibet Plateau
Gravel-block soil is widely distributed in high-cold regions such as Tibet,and its mechanical properties are greatly influenced by the coarse particle content,dry density and moisture content.It is of great importance for evaluating the stability of the deposit slopes in this region.To investigate the influence of coarse particle content and dry density on the strength and particle crushing characteristics of gravel-block soil in the Yarlung Zangbo River Valley region of the Qinghai-Tibet Plateau,large direct shear tests were conducted on gravel-block soil under four coarse particle content conditions,three dry density conditions,and two water content conditions.The stress variation during shearing,particle breakage rate,and volumetric deformation characteristics were analyzed.The results are shown as follows.When the dry density of the sample is 1.4 g/cm3,the stress-strain curve does not exhibit a peak for high coarse particle content (p5≥40％),indicating that the sample does not experience shear failure.With increasing dry density,the critical coarse particle content and vertical pressure for shear failure of the sample continuously decrease.The cohesion of the gravel-block soil exhibits a critical point at p5=20％,with a decrease followed by an increase as the coarse particle content increases.The internal friction angle gradually increases with an increase in p5.The particle breakage rate of the gravel-block soil is positively correlated with the coarse particle content,vertical pressure,and initial dry density.Both increasing coarse particle content and dry density improve the interface shear strength and reduce the final volumetric deformation of the sample.The shear expansion of the sample is influenced by the strength of the interlocking skeleton structure formed by the gravel blocks and the vertical pressure.When σ=100 kPa and p5≥20％,the sample exhibits shear expansion characteristics,which transition to shear contraction with increasing vertical pressure.Under saturated water content conditions,the shear strength of the gravel-block soil decreases,and the final volumetric deformation and shear contraction increase significantly.The researches of this paper can provide guidance for the stability analysis of gravel-block soil landslides in the Qinghai-Tibet Plateau.
large direct shear testcoarse particle contentshear strength parametersparticle crushing rateshear dilation
万方数据
维普
