Effects of drought preceding rainfall on slaking-induced slope instability

本研究探讨了湿化和干燥对泥岩强度和变形特性的影响。当滑坡发生时，人们往往考察降雨的强度-持续时间，但通常不考虑滑坡发生前的干旱条件。作者提出了这样一个假设，即这种干旱和降雨周期会加速地质材料的熟化。首先，我们从不同的来源收集滑坡数据，以确定崩解引起的滑坡。其次，通过模拟干湿循环（D/W）在不同应力条件下进行了一系列直剪试验。在两个D/W阶段，破碎泥岩都发生了显著的蠕变变形，随着D/W数的增加，摩擦角逐渐减小。较高的湿化指数、较低的湿化前含水量和较低的初始密度有利于土工材料的湿化。

This study investigates the effects of wetting and drying on the strength and deformation characteristics of mudstone, known as slaking. When rainfall-induced landslides occur, the intensity-duration of precipitation is often examined, but the drought conditions preceding the landslide-inducing rainfalls are not usually considered. The author proposed a hypothesis that such drought and rainfall cycles would accelerate slaking on the geo-materials. First, we undertook to collect landslide data from various sources in order to identify slaking-induced landslides. Second, a series of direct shear tests was conducted by simulating cyclic drying and wetting (D/W) under different stress condition. Considerable creep deformations on crushed mudstones were found during both D/W phase, and a gradual decrease of friction angle was observed with the increasing number of D/W. Higher slaking index, lower water content before wetting and lower initial density accelerate the slaking of geo-materials.