节理面剪切应力–切向位移曲线峰值后区特性的初步研究

A preliminary study of the post-peak characteristics of shear stress-displacement curves of joints

在节理面剪切试验中,许多剪切应力–位移过程曲线呈现出明显的峰值后区形态。针对这种结构面强度弱化特性,对一组结构面剪切应力–位移过程曲线进行分析,从曲线中获取节理面峰值强度与残余强度。采用一系列应力跌落与塑性流动过程模拟节理面强度弱化过程,通过数值方法再现剪切应力–位移全过程曲线;并进一步研究峰值后区应力–位移曲线与强度弱化的内在关系以及剪胀角演化规律对节理面法向变形的影响,研究成果有助于深化结构面强度与变形特性认识。

During shear test of joints,strength-weakening in post-peak part is observed in many types of shear stress-displacement curves. Aiming at the mechanical characteristics of rock fractures,a set of shear stressdisplacement curves was analyzed,and the peak and residual strength parameters were obtained. The shear stress-displacement curve in the post-peak part was approximated in a stepwise way,and the strength-weakening process was simplified as a series of stress drop and plastic flow during the increase of shear displacement. The complete shear stress-displacement curves were modeled and compared with those obtained by lab tests. Furthermore,the internal relationship between strength-weakening and the shear stress-displacement curve in the post-peak part was studied,and the influence of dilatancy angle on the normal displacement was analyzed. The study helps to deepen the understanding of the mechanical characteristics of rock fractures.