A model experimental study of the formation mechanism of internal erosion caves in fractured loess
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摘要: 黄土台塬边缘裂隙性黄土中洞穴形成机理复杂,且与滑坡、崩塌等地质灾害的发生具有紧密联系,给塬边人民的生产生活造成严重威胁。针对裂隙性黄土中潜蚀洞穴如何形成这一科学问题,以陕西省泾阳县南塬地区典型黄土潜蚀洞穴为试验参考,利用可视化裂隙性黄土潜蚀洞穴形成机理模型试验装置,开展了4组不同初始裂隙开度条件下黄土潜蚀洞穴形成机理模型试验。研究表明:黄土裂隙在水流潜蚀下向黄土潜蚀洞穴的发展过程可分为水力侵蚀阶段、浸润淘蚀阶段和重力崩塌阶段;裂隙性黄土潜蚀洞穴的形成机理可概括为软化崩解-冲刷扩宽-淘蚀临空-重力崩塌;潜蚀输沙量和泥沙输运特征反映了裂隙性黄土渗流潜蚀的发展速率,可分为快速潜蚀阶段、波动降低阶段和缓慢稳定潜蚀阶段;裂隙开度、黄土可蚀性和极限凹槽深度是裂隙性黄土潜蚀洞穴形成的重要影响因子。研究成果对进一步揭示黄土潜蚀的致灾效应提供理论支撑。Abstract: The formation mechanism of caves in fissured loess at the edge of the loess platform plateau is complex and is closely related to the occurrence of geological hazards such as landslides, which pose a serious threat to the production and life of people in this region. To address the scientific problem of how internal erosion caves are formed in the fissured loess, four sets of experiments on the formation mechanism of internal erosion caves in loess under different initial fissure opening conditions are carried out using the visualisation of the internal erosion caves formation mechanism model of the fissured loess in the South Plateau of Jingyang as a reference. The results show that the development process from the fractured loess to the internal erosion of caves under water flowing erosion can be divided into three stages, including the hydraulic erosion stage, the infiltration and erosion stage and the gravity collapse stage. The formation mechanism of the internal erosion caves in the fractured loess can be summarized as follows: Softening and sputtering, scouring and widening, erosion and cavitation, and collapsing by gravity. The development rate of seepage erosion in the fractured loess is reflected by the sediment quantity and transport characteristics, which can be divided into the rapid erosion stage, the fluctuation reduction stage and the slow and stable erosion stage. The fracture opening, the erodibility of loess and the ultimate groove depth are important factors affecting the formation of internal erosion caves in the fractured loess. The research results provide theoretical support to further reveal the disaster-causing effects of loess internal erosion.
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Key words:
- fractured loess /
- internal erosion /
- caves /
- formation mechanism /
- model experiment
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表 1 土样基础物理参数表
Table 1. Basic physical parameters of the soil sample
参数 天然含水量/% 干密度/(g·cm−3) 比重 液限 塑限 取值 17.3 1.5 2.7 26.1 19.5 -
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