| 基于力矩法的元谋干热河谷冲沟沟头土体稳定性模拟与验证 |
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| 引用本文： | 张宝军,熊东红,张光辉,吴汉,张素,袁勇,董一帆.基于力矩法的元谋干热河谷冲沟沟头土体稳定性模拟与验证[J].农业工程学报,2018,34(15):133-140. |
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| 作者姓名： | 张宝军 熊东红 张光辉 吴汉 张素 袁勇 董一帆 |
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| 作者单位： | 中国科学院水利部成都山地灾害与环境研究所/中国科学院山地灾害与地表过程重点实验室;中国科学院教育部水土保持与生态环境研究中心/黄土高原土壤侵蚀与旱地农业国家重点实验室;北京师范大学地理科学学部 |
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| 基金项目： | 国家自然科学基金项目（41571277）；国家重点基础研究发展计划项目课题（2015CB452704） |
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| 摘 要： | 元谋干热河谷冲沟活跃沟头具有"跌坎陡立、内凹洞发育、溯源侵蚀剧烈"等特征,土体崩塌是沟头溯源侵蚀的主要过程之一。该文综合考虑沟头形态特征和裂缝发育等因素,基于力矩分析方法,模拟研究了干热河谷冲沟沟头土体稳定性。结果表明,沟头土体稳定性受土壤含水量、内凹洞发育高度、裂缝发育深度及其距沟壁的距离等多个因素影响。沟头土体稳定性系数,随土壤含水量和裂缝发育深度的增大呈显著指数函数降低,随内凹洞发育高度的增大呈显著线性函数降低,随裂缝发育距沟壁距离的增大呈二次多项式增大。以土壤含水量作为标准对模拟结果进行了检验,发现沟头土体失稳崩塌时,崩塌体和崩塌面实测的土壤含水量分别为模拟值的69.8%~87.6%和82.0%~95.5%,评价结果较为可靠。崩塌面土壤含水量与模拟值更为接近,说明裂缝发育对沟头土体稳定性非常重要。研究结果可为元谋干热河谷沟头土体崩塌预测及沟头治理措施制定提供重要的理论参考。
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| 关 键 词： | 土壤 侵蚀 内凹洞 土体稳定性 溯源侵蚀 冲沟沟头 元谋干热河谷 |
| 收稿时间： | 2018/3/28 0:00:00 |
| 修稿时间： | 2018/6/13 0:00:00 |
Simulation and verification of overhanging soil layers stability of gully heads in Yuanmou Dry-hot Valley based on moment method |
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| Zhang Baojun,Xiong Donghong,Zhang Guanghui,Wu Han,Zhang Su,Yuan Yong and Dong Yifan.Simulation and verification of overhanging soil layers stability of gully heads in Yuanmou Dry-hot Valley based on moment method[J].Transactions of the Chinese Society of Agricultural Engineering,2018,34(15):133-140. |
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| Authors: | Zhang Baojun Xiong Donghong Zhang Guanghui Wu Han Zhang Su Yuan Yong and Dong Yifan |
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| Institution: | 1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; 2. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Research Center of Soil & Water Conservation and Ecological Environment, Chinese Academy of Sciences, Yangling 712100, China;,1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China;,3. Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China,1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China;,1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China;,1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; and 1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; |
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| Abstract: | Abstract: Gully erosion is one of the major contributors to severe land degradation in the Yuanmou Dry-hot Valley Region of Southwest China, due to the frequent erosive precipitation events in the rainy season and special lithological conditions. Most active gullies in the study area are characterized by steep gully headcut, and headward erosion has been recognized as the main process of gully expansion. In particular, scour holes are often developed in the open side of gully headcut, which cause the frequent collapse of overhanging layers of gully heads in the process of headward erosion, and thus accelerate gully headward development. It is, therefore, of great significance to carry out the study on the collapse of overhanging layers of gully heads during the gully headward processes. In this study, based on the field investigations, a generalized physical model of active gully head was established. Then, the stability of overhanging layer of active gully head was studied by the momental analysis method, considering the main factors i.e. headcut height, the shape of scour hole and the development of tension crack at gully head. The results showed that the stability of overhanging layer of gully head was affected by various factors, such as the soil water content, the height of scour hole, the location and depth of tension crack. The results also indicated the difficulty in studying the mechanism of the gully head collapse process. When other parameters were assigned with default values, the stability of overhanging layer of gully head was decreased with soil water content and depth of tension crack (p<0.001) as an exponential function, and decreased with height of scour hole (p<0.001) as a linear function. As the distance between the tension crack and the headcut wall increased, the stability of overhanging layer increased significantly (p<0.001). Furthermore, to test the reliability of the evaluation of stability of overhanging layers, 4 gully heads molded by man with scour holes and the flow scouring experiments were employed in the field. When the collapse of overhanging layers of gully heads occurred, soil water contents of the whole collapse soil and the collapse surface soil were determined by oven-dry method with 6 repetitions. The results showed that the measured soil water contents of the whole collapse soil and the collapse surface soil were 69.8%-87.6% and 82.0%-95.5% of the model estimated values, separately. The small difference in soil water contents between the measured values and estimated values also indicated that this evaluation model was very valuable for the prediction of the collapse of overhanging layers of gully heads in the Yuanmou Dry-hot Valley Region. Moreover, the soil water content of the collapse surface soil was much closer to the model estimated value, which demonstrated that the development of tension crack on the overhanging layers of gully heads did affect their stability. These results are helpful to supplement meaningful theories to the erosion mechanism study and conservation practices implementation of active gully heads in the Yuanmou Dry-hot Valley Region. However, due to the complexity and uncertainty of the collapse of overhanging layers, further studies are needed to focus on the process of collapse of active gully heads, which can further improve the evaluation reliability of the stability model. |
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| Keywords: | soils erosion scour hole stability of overhanging layer headcut erosion gully head Yuanmou Dry-hot Valley Region |
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