To investigate frictional properties of the rupture surface of the carbonate Jiweishan rock avalanche, we conducted high-velocity-friction tests on the limestone and shale samples at different shear rates. The samples showed shear- and rate-strengthening of friction at low shear rates, but transformed to shear- and rate-weakening of friction at large shear rates. The critical shear rate was deduced to be between 0.05 and 0.2 m/s in our tests. The friction coefficient reduced to an extremely low value of less than 0.1 at a shear rate of 2.1 m/s. The sliding rock mass therefore could slide out of the rupture surface at a high velocity and consequently traveled a long distance as granular debris. Two mechanisms may have reduced the frictional resistance. Recrystallized calcite nanograins and CaO nanograins produced through calcite decomposition covered and lubricated the shear surface. Furthermore, the CO₂ emitted through calcite decomposition reduced the effective normal stress and therefore the friction on the surface. Our conclusions for Jiweishan rock avalanche are also useful for understanding the high mobility of other widely distributed carbonate rock avalanches.

为了研究碳酸盐岩鸡尾山岩崩破裂面的摩擦特性，我们对石灰岩和页岩样品在不同剪切速率下进行了高速摩擦试验。样品在低剪切速率下表现出剪切和速率强化的摩擦，但在大剪切速率下转化为摩擦的剪切和速率减弱。在我们的测试中，临界剪切速率推断为 0.05 和 0.2 m/s 之间。在2.1 m/s 的剪切速率下，摩擦系数降至低于 0.1 的极低值。因此，滑动的岩体可以高速滑出破裂面，从而作为颗粒状碎片移动很长一段距离。两种机制可能降低了摩擦阻力。重结晶方解石方解石分解产生的纳米颗粒和CaO纳米颗粒覆盖并润滑了剪切面。此外，通过方解石分解释放的CO ₂降低了有效正应力，因此降低了表面的摩擦力。我们对鸡尾山岩崩的结论也有助于理解其他广泛分布的碳酸盐岩雪崩的高流动性。