压实黄土淤地坝“陡坎”冲蚀特性研究  

Study on head-cut erosion characteristics of compacted loess check dams

作　　者：单熠博 陈生水[1,2] 钟启明 王琳[3] 杨蒙 卢洪宁[1] 陈小康 SHAN Yibo;CHEN Shengshui;ZHONG Qiming;WANG Lin;YANG Meng;LU Hongning;CHEN Xiaokang(Nanjing Hydraulic Research Institute,Nanjing,Jiangsu 210029,China;Key Laboratory of Reservoir and Dam Safety,Ministry of Water Resources,Nanjing,Jiangsu 210029,China;State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China,Xi'an University of Technology,Xi'an,Shaanxi 710048,China)

机构地区：[1]南京水利科学研究院,江苏南京210029 [2]水利部水库大坝安全重点实验室,江苏南京210029 [3]西安理工大学省部共建西北旱区生态水利国家重点实验室,陕西西安710048

出　　处：《岩石力学与工程学报》2023年第9期2315-2328,共14页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51909214,52279111);中央级公益性科研院所基本科研业务费专项资金项目(Y320005)。

摘　　要：近年来短时强降雨导致我国黄土高原地区淤地坝水毁灾害频发,鉴于该领域研究基础薄弱,不同因素影响下压实黄土冲蚀特性和“陡坎”冲蚀机制尚不明晰。开展黄土材料微观孔隙结构的定性和定量测试,以及14组压实黄土“陡坎”冲蚀水槽试验,重点研究初始含水率和压实度对“陡坎”冲蚀过程的影响,揭示压实黄土微观孔隙结构对“陡坎”冲蚀模式和冲蚀速率的影响机制。试验结果表明:压实黄土持水状态是影响“陡坎”冲蚀模式和冲蚀速率的重要因素,水分子通过影响黄土的微观孔隙结构进而改变土体的宏观冲蚀规律;土体在低含水率状态下,“陡坎”以层状冲蚀为主,由基质吸力提供的“假黏聚力”对冲蚀速率影响较小;随着土体含水率提高,“陡坎”冲蚀模式发生转变,以间歇性块体失稳的形式向上游溯源冲蚀;压实度的改变不影响“陡坎”冲蚀模式,而是通过调整颗粒骨架、颗粒接触面积影响“陡坎”冲蚀速率,其量值提高能够显著增强黄土的抗冲蚀能力。研究成果可为压实性黄土淤地坝溃坝机制研究及灾害预测提供理论支撑。In recent years,water-induced failures of check dams frequently occurred due to short-time heavy rainfalls in Loess Plateau in China.The research foundation on check dam breach simulation is weak,while the erosion characteristics of compacted loess and the head-cut erosion mechanism under the influence of different factors are still unclear.Qualitative and quantitative tests on microscopic pore structures of loess material,and 14 groups of head-cut erosion flume tests of compacted loess have been conducted.In this study,the influences of initial water content and compactness on head-cut erosion process are the main concern,and the influence mechanisms of compacted loess microscopic pore structure on the head-cut erosion mode and rate have been revealed.The model test results show that the water-holding state of compacted loess has an essential impact on head-cut erosion mode and rate.Water molecules change the macroscopic erosion law by affecting the microscopic pore structure of compacted loess.When the soil is in a low water content state,the head-cut is dominated by layered erosion,and the“false cohesion”provided by matrix suction has little impact on the erosion rate.With the increase of water content,the head-cut erosion mode has changed into retrogressive erosion towards upstream accompanied by intermittent instability of blocks.However,the change of compactness does not affect the head-cut erosion mode,but the head-cut erosion rate by adjusting particle skeleton and contact area.The increase of compactness can significantly enhance the erosion resistance of loess.The research results can provide theoretical support for the study of dam breach mechanisms of loess check dams.

关 键 词：土力学 淤地坝 压实性黄土 初始含水率 压实度 微观结构 “陡坎”冲蚀 

分 类 号：TU43[建筑科学—岩土工程]