Understanding the shear stress recovery mechanism during the stick-slip motion is a fundamental requirement for predicting the sliding behavior of rock joints. In this study, slide-hold-slide (SHS) type direct shear experiments under constant normal stress are performed on granite joints with significant roughness components to investigate the effects of compaction and dilation on the shear stress recovery. The shear stress recovery of rock joints is contributed by the growth of the contact area induced by the compaction during the hold period and the enhancement of dilation work during the re-shear process. The contact area reaches the maximum value under relatively low normal stress after the long hold period. Then, the dilation gradually contributes to the shear stress recovery because the welded asperities or grains are assembled, and the slide needs to ride over these bonded areas. The surface roughness plays a significant role in the shear stress recovery since the initial aperture and asperity morphology affect the compaction and dilation. The greater magnitude of shear stress recovery observed on rougher surfaces can be attributed to the effective normal closure during the hold period and significant dilation after the long hold periods.

中文翻译：

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考虑节理压实和剪胀的岩石节理剪应力恢复的室内观察

了解粘滑运动过程中的剪应力恢复机制是预测岩石节理滑动行为的基本要求。在这项研究中，在具有显着粗糙度成分的花岗岩节理上进行了恒定法向应力下的滑动-保持-滑动（SHS）型直剪实验，以研究压实和膨胀对剪应力恢复的影响。岩石节理剪应力的恢复是由于保持期间的压实引起的接触面积的增长和再剪切过程中的膨胀功的增强所致。经过长时间的保持后，接触面积在相对较低的正应力下达到最大值。然后，膨胀逐渐有助于剪切应力的恢复，因为焊接的粗糙体或晶粒被组装起来，并且滑块需要滑过这些粘合区域。表面粗糙度在剪切应力恢复中起着重要作用，因为初始孔径和粗糙形态影响压实和膨胀。在粗糙表面上观察到的更大程度的剪切应力恢复可归因于保持期间的有效正常闭合以及长时间保持期间后的显着扩张。