粗糙节理直剪特性试验研究

Experimental Research on Direct Shear Characteristics of Rough Joints

利用高强度石膏浇筑3组不同粗糙度节理面试样,进行常法向应力约束条件下的直剪试验,研究了粗糙度和充填物对节理剪切力学行为的影响。研究表明:节理剪切应力-剪切位移曲线受粗糙度、充填物的影响,可分为有峰型与无峰型两类;节理峰值剪应力随粗糙度增加而增大,而充填物的存在弱化了粗糙度对剪切强度的影响;非充填节理与粗糙度较大的充填节理在法向变形方面均呈先剪缩后剪胀类型,对于粗糙度较小的充填节理,其剪胀行为主要受充填物控制,表现为纯剪缩类型;节理破坏类型不是单一的,整个剪切过程是滑移、啃断、断裂和拉伸破坏等行为的组合,通过试验分析,可将节理岩体破坏机制划分为滑移-切齿机制、切齿-断裂机制、充填界面间滑移-不完全剪断机制。

Three groups of joints samples with different roughness were casted by high-strength gypsum material and a series of constant normal load shear test were carried out to study the influences of roughness and filling material on the shear mechanical properties of joints.The results show that the shear stress versus shear displacement curves can be divided into peak and gentle types caused by the influences of roughness and filling material.The peak shear stress of rock joints increases with the increase of roughness,and the filling material weakens the significance of roughness on shear strength.Both the non-filling joints and the filling joints with large roughness are of the type of shear contraction first and then dilatancy in terms of normal deformation.For the filling joints with small roughness,the dilatancy behavior is mainly controlled by the filling material and shows the type of pure compression.Joint failure type is not single.The shear failure process is a combination of slipping,cracking,and shear or tensile.Through experimental analysis,the failure mechanism of rock-jointed mass is categorized into the slipping-cutoff,cutoff-cracking,slipping-incomplete shear between filling interfaces.