| 降雨入渗下裂土边坡水分运移时空特征与失稳机理 |
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| 引用本文： | 周峙,张家铭,宁伏龙,罗易,王建立.降雨入渗下裂土边坡水分运移时空特征与失稳机理[J].交通运输工程学报,2020,20(4):107-119. |
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| 作者姓名： | 周峙 张家铭 宁伏龙 罗易 王建立 |
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| 作者单位： | 1.中国地质大学(武汉) 工程学院，湖北 武汉 4300742.安徽交通控股集团有限公司，安徽 合肥 230088 |
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| 基金项目： | 中央高校基本科研业务费专项;国家自然科学基金;安徽省交通运输科技进步计划项目 |
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| 摘 要： | 为探究降雨入渗下裂土边坡水分运移时空特征与失稳机理, 自主研制了足尺模型试验系统和光纤布拉格光栅(FBG)深部柔性位移系统, 对边坡渐进破坏进行了全过程、多物理量联合监测, 揭示了降雨入渗作用下裂土边坡的渐进变形和破坏演化模式; 基于裂土边坡的渐进破坏模式, 提出了土体饱和比概念, 将裂隙深度范围滑体分为饱和层和非饱和层; 以土体饱和度变化描述了含随机分布裂隙的边坡水分运移规律, 并结合刚体极限平衡法探讨了由裂隙控制的边坡失稳机制。研究结果表明: 对于未形成裂隙的边坡, 连续降小雨时浅层变形受表层基质吸力控制; 裂隙形成后, 雨水沿裂隙快速入渗形成暂态饱和区, 导致基质吸力降幅达82.50%~87.14%, 而由其贡献的抗剪强度迅速损失, 从而形成初期溜滑、片蚀等浅层变形, 降雨停止后坡体仍处于蠕变过程, 坡脚与坡顶位移增幅分别为23.40%和19.39%;蒸发后裂隙规模发展增大了雨水对渗流场的影响范围和边坡破坏规模; 土体经历胀缩、蠕变而变得松散, 裂缝区深部土体体积含水率较初始状态的增幅为205.7%;同一降雨条件下, 初始裂隙深度愈深, 稳定系数愈低, 破坏愈快; 对具有同一裂隙深度的边坡, 其稳定系数随土体饱和比的增加逐渐降低, 土体饱和比增长愈快, 表征边坡内部出现大面积连通型饱和区, 这是裂土边坡出现整体失稳的主要原因。
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| 关 键 词： | 路基工程 裂土边坡 足尺模型 变形机理 土体饱和比 光纤布拉格光栅 |
| 收稿时间： | 2020-03-01 |
Temporal and spatial characteristics of moisture migration and instability mechanism of cracked soil slope under rainfall infiltration |
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| ZHOU Zhi,ZHANG Jia-ming,NING Fu-long,LUO Yi,WANG Jian-li.Temporal and spatial characteristics of moisture migration and instability mechanism of cracked soil slope under rainfall infiltration[J].Journal of Traffic and Transportation Engineering,2020,20(4):107-119. |
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| Authors: | ZHOU Zhi ZHANG Jia-ming NING Fu-long LUO Yi WANG Jian-li |
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| Affiliation: | 1.School of Engineering, China University of Geosciences, Wuhan 430074, Hubei, China2.Anhui Transportation Holding Group Co., Ltd., Hefei 230088, Anhui, China |
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| Abstract: | To reveal the temporal and spatial characteristics of moisture migration and instability mechanism of cracked soil slope under the rainfall infiltration. The full-scale model test and fiber Bragg grating(FBG) displacement systems were developed independently to conduct the whole-process and multi-physical monitoring of slope progressive failure. The progressive deformation and failure evolution mode of cracked soil slope under the rainfall infiltration were revealed. Based on the progressive failure mode of cracked soil slope, the concept of soil saturation ratio was proposed. The sliding body within the crack depth range was divided into the saturated layer and unsaturated layer. The change of soil saturation degree was used to describe the water transport law of slope with randomly distributed cracks, and the slope instability mechanism controlled by cracks was discussed by combining with the rigid body limit equilibrium method. Research result indicates that the shallow deformation is controlled by the surface matrix suction in the case of continuous light rain for the slope without cracks. After the formation of cracks, the rainwater infiltrates rapidly along the cracks to form a transient saturated zone. It causes a rapid loss of shear strength contributed by the matrix suction with a drop of 82.50%-87.14%, and produces the initial slip flow, sheet erosion and other shallow deformations. After the rainfall stops, the slope is still in the creep process, and the displacements of slope foot and roof increase by 23.40% and 19.39%, respectively. After the evaporation, the development of crack increases the influence range of rainwater on the seepage field and slope failure scale. The soil becomes loose after experienced swelling, shrinking and creep process. The volumetric moisture content of soil at the deep layer of crack zone increases by 205.7% compared with the initial state. Under the same rainfall condition, the deeper the initial crack depth is, the lower the stability coefficient is, and the faster the failure occurs. For a slope with the same crack depth, its stability coefficient decreases with the increase of soil saturation ratio. The faster the soil saturation ratio increases, the wider the connected saturated zone inside the slope is. It is the main reason for the overall instability of cracked soil slope. |
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