Abstract Collapsing erosion is very severe in subtropical regions that are covered extensively by granite residual soil. However, detailed information about hydraulic responses during collapsing erosion, especially for different slope angles, remains unclear. Therefore, to control collapsing erosion, it is important to attain a more comprehensive understanding of the complex hydraulic responses due to rainfall. In this study, an artificial rainfall simulator and an experimental device were used to evaluate the collapsing erosion process, with particular consideration of the influence of slope angle. Flume experiments using three slope angles (0, 10, and 20°) were performed under artificial rainfall. This study explored the evolutions and hydraulic responses of collapsing erosion of granite residual soil by simultaneously monitoring moisture content, pore-water pressure, and wetting front during heavy rainfall. The results showed that collapsing erosion occurred faster with steeper slope angle. Collapse occurred in an upslope direction, when the corresponding moisture content of the soil was between 30% and 40%. Pore-water pressure increased until the development of collapsing erosion but was released when the soil mass collapsed. The descending process of the wetting front on a gentle slope and a steep slope can be divided into two stages and three stages, respectively. This study presents an improved characterization of collapsing erosion and provides valuable evidence for slope-angle impacts on infiltration events during collapsing erosion under heavy rainfall.

中文翻译：

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不同坡度崩塌侵蚀过程中花岗岩残积土的含水量、孔隙水压力和湿锋

摘要 在花岗岩残积土覆盖广泛的亚热带地区，崩塌侵蚀非常严重。然而，关于塌陷侵蚀过程中水力响应的详细信息，尤其是对于不同坡度，仍不清楚。因此，为了控制塌陷性侵蚀，更全面地了解降雨引起的复杂水力响应是很重要的。在这项研究中，人工降雨模拟器和实验装置被用来评估塌陷侵蚀过程，特别考虑了坡角的影响。在人工降雨下进行了使用三个倾斜角（0、10 和 20°）的水槽实验。本研究通过同时监测大雨期间的含水量、孔隙水压力和湿锋，探讨了花岗岩残余土壤塌陷侵蚀的演变和水力响应。结果表明，坡角越大，崩塌侵蚀发生得越快。塌陷发生在上坡方向，当相应的土壤含水量在30%到40%之间时。孔隙水压力增加直到发生塌陷侵蚀，但在土体塌陷时释放。缓坡和陡坡润湿锋的下降过程可分为两个阶段和三个阶段。