| 黑方台地区马兰黄土渗透特性及结构损伤试验研究 |
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| 引用本文： | 李泽坤,马鹏辉,彭建兵,杨炬.黑方台地区马兰黄土渗透特性及结构损伤试验研究[J].地质科技通报,2022,41(6):200-210. |
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| 作者姓名： | 李泽坤 马鹏辉 彭建兵 杨炬 |
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| 作者单位： | 长安大学地质工程与测绘学院, 西安 710054 |
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| 基金项目： | 国家自然科学基金项目42090053国家自然科学基金项目41790441国家自然科学基金项目42041006国家自然科学基金项目4210071970中央高校基础研究基金300102262907 |
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| 摘 要： | 持续引水灌溉改变了马兰黄土的结构, 降低了土体的抗剪强度, 导致黑方台地区黄土滑坡频繁发生, 严重影响着当地居民生命和财产安全。为了明析马兰黄土的渗透过程, 取黑方台马兰黄土为研究对象, 分别开展核磁共振(NMR)试验及扫描电镜(SEM)试验, 以解释此类黄土在不同初始含水率及不同干密度下的渗透特性及结构损伤微观特征。研究结果表明: 入渗速率与土体初始含水率呈负相关关系, 土体初始含水率越高, 其充水微小孔隙增加速率越慢, 充水中大孔隙增加速率越快; 入渗速率与土体干密度呈负相关关系, 且会率先形成高含水率区域, 土体干密度越大, 其充水微小孔隙增加越慢, 充水中大孔隙增加越快。入渗前后对比发现, 试样初始含水率越高, 微小孔隙增加比例越小, 颗粒间接触方式变化越不明显; 干密度越大的试样不同孔隙体积基本按等量变化, 接触面积明显减少, 形成更多的架空孔隙, 连通性较好, 具有较好的储水能力。入渗后试样原本的致密结构丧失, 颗粒破碎严重, 部分细长状颗粒向似椭圆状颗粒演化, 颗粒间接触方式变为点边接触, 粒间胶结作用遭受损伤破坏, 甚至部分团粒中颗粒分离、脱落, 使得土体强度丧失, 最终导致滑坡发生。研究结果可为黄土滑坡的防治提供依据。
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| 关 键 词： | 黄土 核磁共振 扫描电镜 土体入渗 孔隙结构 结构损伤 黑方台地区 |
| 收稿时间： | 2022-08-13 |
Experimental study on the permeability characteristics and structure damage of Malan loess in Heifangtai area |
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| Institution: | College of Geological Engineering and Geomatics, Chang'an University, Xi'an 710054, China |
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| Abstract: | Continuous water diversion irrigation has changed the structure of Malan loess, led to the reduction of the shear strength of the soil, and thus the frequent occurrence of landslides in the Heifangtai area, which seriously affected the lives and property safety of local residents. In order to analyze the infiltration process of Malan loess, nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) tests were respectively carried out to investigate the permeability and structural damage microscopic characteristics for loess at different initial water contents and different dry densities. The obtained results show that the infiltration rate is negatively correlated with the initial moisture content of the soil. The density is negatively correlated, and it will take the lead to a higher water content area. The water content is higher, the increase in the proportion of micropores is smaller, and the less obvious the change in the contact mode between particles; the dry density of the sample is larger, the different pore volumes basically change in the same amount, the contact area is significantly reduced, and more overhead pores are formed, which are connected to each other, leading to good water storage capacity. After infiltration, the original dense structure of the sample is lost, and the particles are severely broken. Some slender particles evolve into nearly round particles or elliptical particles, and the contact mode between particles becomes point-edge contact.The intergranular cementation is damaged and destroyed, and even some particles in the aggregates are separated and fall off, resulting in the loss of soil strength and eventually leading to landslides. The results can provide a basis for the prevention and control of loess landslides. |
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