Abstract The presence of fault gouge and the generation of wear material between two sliding rock surfaces plays a critical role in slip weakening and propagation of ruptures along underground brittle shear fractures forming ahead of tabular excavations in deep and high stress gold mining. We performed two types of friction experiments: one with a fault gouge layer between two sliding surfaces, and the other without a fault gouge layer ‘rock-on-rock’, both under room dry conditions at slip velocities ranging from ~1.0 mm/s to 1200 mm/s. These friction experiments revealed a remarkable difference in the frictional weakening behaviour, e.g., rock-on-rock friction experiments show weakening behaviour at lower slip velocity (~5 mm/s) and generally has lower frictional strength than those with the intervening fault gouge between sliding surfaces. This study shows that the existence of the fault gouge layer between sliding rock surfaces delays the onset of fault weakening (i.e., slip weakening displacement of gouge layer experiments is larger compared to rock-on-rock experiments). It is proposed that flash heating may be the main active weakening mechanism within both our gouge and rock-on-rock experiments, and provides a feasible account for the observed weakening. The observed slip weakening displacement (Dc) differences may be attributed to the presence of a gouge layer between sliding surfaces, which has many more contacts during sliding compared to rock-on-rock experiments, thus reducing the average slip velocity per contact, consequently, the potential for activation of flash heating which delays the onset of weakening. Here we suggest that we may be able to describe brittle shear fracture rupture propagation process along underground brittle shear zones by conducting low, intermediate and high slip velocity friction experiments with and without an intervening fault gouge between sliding rock surfaces. These findings should have important implications for the modelling of rupture propagation processes in underground shear zones, a phenomenon that influences the severity of rockbursts, and hence the safety of mine workers and mining operations.

中文翻译：

---

凿层对深部高应力矿山脆性剪切裂缝破裂扩展的影响

摘要 断层泥的存在和两个滑动岩石表面之间磨损材料的产生对深部高应力金矿开采中板状开挖前形成的地下脆性剪切裂缝的滑动减弱和破裂的扩展起着关键作用。我们进行了两种类型的摩擦实验：一种在两个滑动面之间有断层泥层，另一种没有断层泥层“岩石对岩石”，均在室温干燥条件下，滑动速度范围为 ~1.0 毫米/秒到 1200 毫米/秒。这些摩擦实验揭示了摩擦减弱行为的显着差异，例如，岩石对岩石摩擦实验在较低的滑动速度（~5 mm / s）下表现出减弱行为，并且通常比具有介于两者之间的断层泥的摩擦强度低。滑动面。本研究表明滑动岩面间断层泥层的存在延迟了断层弱化的开始（即泥层实验的滑动弱化位移比岩对岩实验大）。在我们的凿岩和岩对岩实验中，提出快速加热可能是主要的主动弱化机制，并为观察到的弱化提供了可行的解释。观察到的滑动减弱位移 (Dc) 差异可能归因于滑动表面之间存在凿层，与岩石对岩石实验相比，滑动过程中具有更多的接触，从而降低了每次接触的平均滑动速度，因此，激活闪光加热的可能性，从而延迟减弱的开始。在这里，我们建议我们可以通过在滑动岩石表面之间有和没有介入断层泥的情况下进行低、中和高滑动速度摩擦实验，来描述脆性剪切断裂破裂沿地下脆性剪切带的扩展过程。这些发现应该对地下剪切带破裂传播过程的建模具有重要意义，这种现象会影响岩爆的严重程度，从而影响矿工和采矿作业的安全。