充填粗糙节理直剪数值模拟宏细观分析

Simulation and Macro-Mesoscopic Parameter Analysis for Direct Shear of Filled Rough Joints

利用颗粒流数值计算方法对岩石充填节理直剪作用下力学性质进行研究,从细观角度分析不同法向荷载下粗糙节理面的损伤情况;探讨充填节理粗糙程度、充填物强度参数、充填物与围岩接触面强度以及充填厚度对节理剪切强度的影响,结果表明:(1)随着法向荷载的增大,上下节理面接触状态及粘结力分布规律发生转变,充填节理面粘结破坏明显增加;(2)节理粗糙度系数(JRC)对峰值剪切应力的影响较大;随JRC的增加节理峰值剪切强度增大;节理面粘结力呈类线性增长,而内摩擦角随JRC的增大而呈明显的非线性变化;(3)随节理充填物粘结强度比的增加,峰值剪切应力增大;随充填物强度比的增加,节理面粘结力出现明显的增长,而内摩擦角呈现先下降后增加的趋势;(4)当法向荷载较小时,峰值剪切应力受接触面粘结强度比的影响较大;当法向荷载较大时,其对峰值剪切应力的影响程度明显降低.节理面粘结力和内摩擦角随接触面粘结的增加分别呈现出非线性增长和下降的趋势.(5)节理剪切力学形式随充填后的增加呈现降低的趋势,然而随着厚度的不断增加,所带来的剪切力学参数变化程度逐渐减小.

A joint model based on particle flow was built successfully and the mechanical properties of the fill joint were investigated in this study. The morphology of damage and the crack evolution mechanism of roughness of the jointed model were also analysed from the viewpoint of meso-mechanics.At the same time,the influence of the value of the JRC（ joint roughness coefficient）,fill strength,interface,and fill thickness on the mechanical behaviour have been analysed. The detailed results are as follows：（ 1） The normal stress has a significant influence on the peak shear stress,contact condition,and contact force of the joint. With higher stress,the bond break at the joint surface becomes apparent;（ 2） The joint peak shear stress increases with an increase in the JRC value,and the shear strength parameters for cohesion and friction angle exhibit linear and nonlinear increases withthe increase in the JRC value,respectively;（ 3） The joint peak shear stress increases with the strength of filling material. However,the strength of filling material has a different influence on the cohesion and friction angle of the fill joint. Cohesion increases with an increase in material strength. The friction angle decreases as the fill strength ratio changes from 0. 1 to 0. 3,and increases when the fill strength ratio exceeds 0. 3;（ 4） When the normal constant load is small,the interface has a significant influence on the peak shear stress,but when the normal constant load is large,the influence is weaker. Joint shear-strength parameters for cohesion increase with the increase in the strength of interface,but the friction angle shows the opposite trend with cohesion;（ 5） With increasing fill thickness,the mechanical parameters of the joint model exhibit an obvious downward trend. However,with a further increase in thickness,the decrement in the mechanical parameters is less pronounced.