EXPERIMENTAL STUDY ON DEFORMATION AND FAILURE MECHANISM OF SHALLOW LOESS LANDSLIDE UNDER THE EFFECT OF IRRIGATION
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摘要: 为有效减少泾阳地区大面积灌溉活动诱发黄土滑坡对社会和经济带来的巨大损失,开展灌溉型滑坡室内实验研究,研究坡度在灌溉条件下对黄土滑坡变形破坏过程影响,具有重大的现实意义。本次实验设计了可用于坡顶和坡面的灌溉装置,同时进行了45°斜坡和60°斜坡的两组室内灌溉模型实验,且每组斜坡内埋设体积含水率传感器、基质吸力传感器和孔隙水压力传感器三种传感器记录其内部变化。通过对两组实验过程及结果进行对比分析,进而得出灌溉条件下浅表层黄土滑坡的变形破坏规律,总结出该类滑坡的破坏模式及其诱发机理。实验结果表明,实验前期随着体积含水率不断增大,基质吸力逐渐减小至基本稳定,土体强度随之减小;实验后期上部土体饱和,斜坡产生的变形和土体排水不畅产生了超孔隙水压力,有效应力随之减小,土体强度减小至最小,导致滑坡产生。同时,坡度越大,滑坡越易发生,滑面深度和滑动距离越小。Abstract: In order to effectively reduce the enormous losses to society and economy caused by shallow loess landslides triggered by irrigation in large area of Jingyang, it is of great realistic significance to carry out laboratory experimental study on irrigation-induced landslides and to study the effects of slope gradient on deformation and failure process of loess slope under irrigation condition. Irrigation rig used for slope surface and slope top irrigation was designed. In the meanwhile, two groups of indoor physical model experiments respectively with slope of 45 degrees and slope of 60 degrees were conducted, and three kinds of sensors namely volume moisture sensors, matric suction sensors and pore water pressure sensors were buried inside the slopes to record the internal changes. Based on the analysis and the comparison of the experimental procedures and results of two groups, the deformation and failure law of shallow loess landslide under irrigation condition is disclosed, and the failure mode and the triggering mechanism of this kind of landslides are summarized. The experimental results show that, at the early stage of the experiments, with the continuous increases of volume moisture, the matric suction of the loess decreased gradually and maintained stable in the end while the strength reduced accordingly at the later stage, the upper loess of the slope reached the saturation stage, excess pore water pressure was generated by the slope deformation and poor drainage of the loess, which decreased the effective stress and the strength of the loess. As a result, the strength reached the minimum, which resulted in landslides. And meanwhile, the steeper a slope is, the greater probability of landslide occurrence is, and the smaller the depth of sliding surface and sliding distance are.
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Key words:
- Loess slope /
- irrigation /
- landslide /
- physical model experiment /
- pore water pressure
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表 1 实验黄土的物理参数
Table 1. Physical parameters of the loess used in experiments
天然重度/(kN/m3) 初始体积含水率/% 饱和体积含水率/% 塑限WP/% 液限WP/% 塑性指数IP 14.7 10 43 17.2 28.0 10.9 表 2 滑坡发展过程和滑动时间
Table 2. Development and sliding times of landslides
斜坡实验 主要破坏类型 现象描述 累计灌溉/L 整体滑动时间/min 60°斜坡 浅层滑动破坏 ①前缘坡脚侵蚀。②距离坡肩约10 cm处产生宽3 mm裂隙。③破坏较快,滑动距离远,最远达19 cm。 124.8 360 45°斜坡 浅层滑动破坏 ①坡脚冲蚀严重,形成临空面。②后缘轻微塌陷,出现1条贯通的拉裂隙距坡肩约13 cm。③滑动2 s完成,最远达到20 cm。 168.5 486 -
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