含石量对土石混合体剪切特性影响的颗粒离散元数值研究

摘要

DEM numerical models based on PFC2D contact bond model are performed to probe the impact of stone content variation to shear properties of soil-rock mixture (S-RM).The micro parameters of unbound granular materials are calibrated with lab large-scale direct shear tests.Then the shear properties of S-RM of different stone content under different normal stress are studied.The result shows that for S-RM under the same normal stress,the high stone content would result in the high peak shear stress,the high shear strain at peak shear stress,the high post-softening strength,the stronger dilatation behavior,the more shear "leap" behavior.The friction angle of the S-RM increases and the cohesion decreases with the increase of the stone content.The cohesion keeps almost constant after stone content exceeds 50％.For S-RM with the same stone content,the high normal stress would have the high peak shear stress and the stronger strain-softening behavior.The shearing process of S-RM mainly overcomes the friction energy and strain energy are overcome whilst the change of the kinetic energy is almost zero.%采用基于PFC2D接触黏结模型的离散元数值模型,探讨含石量变化对土石混合体剪切特性的影响.利用室内大型直剪试验对表征土石混合体细观力学性质的模型参数进行标定,模拟分析了4种不同含石量土石混合体在4种不同围压作用下的剪切特性.试验结果表明:相同法向应力作用下,含石量越高,峰值剪应力越大,达到峰值剪应力时的剪应变越大,软化后强度越高,剪胀特性越强,剪切“跳跃”现象越明显.土石混合体摩擦角随含石量增高而增大;黏聚力随含石量增高而减小,含石量超过50％后基本不变.相同含石量的土石混合体,法向应力越高,峰值剪应力越大,应变软化特性越强.土石混合体剪切过程中以克服摩擦能和应变能为主,动能变化几乎为零.