不同层间系数条件下双层地基潜蚀可视化试验研究  

Visual experimental study on suffusion in double-layered soil under different retention ratios

作　　者：罗玉龙[1] 李澳 张海彬 张兴杰 游春华[2] 袁小龙[3] 盛金昌[1] 王惠民 LUO Yulong;LI Ao;ZHANG Haibin;ZHANG Xingjie;YOU Chunhua;YUAN Xiaolong;SHENG Jinchang;WANG Huimin(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing,Jiangsu 210098,China;School of Civil and Architecture Engineering,Hunan Institute of Technology,Hengyang,Hunan 421002,China;Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining,Qinghai 810008,China)

机构地区：[1]河海大学水利水电学院,江苏南京210098 [2]湖南工学院土木与建筑工程学院,湖南衡阳421002 [3]中国科学院青海盐湖研究所,青海西宁810008

出　　处：《岩石力学与工程学报》2024年第1期226-235,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：湖南省水利科技项目(XSKJ2021000–35,XSKJ2022068–37);中国科学院青海盐湖研究所基础研究青年创新交叉团队(islJCTD–2022–2)。

摘　　要：地层结构显著影响潜蚀的发生、发展过程,然而,目前大部分研究多集中在单一土体发生潜蚀的几何条件与水力条件方面,很少考虑地层结构的影响。针对实际工程中常见的地基结构——双层强透水地基,上层由内部稳定土体组成,充当反滤层,下层为内部不稳定土体,利用自行研制的基于平面激光诱导荧光技术的潜蚀可视化试验装置,开展不同层间系数条件下双层地基潜蚀可视化试验研究,重点探讨层间系数对潜蚀发生、发展过程的影响机制。试验结果表明:上层土体能够显著提高下层土体潜蚀发生的临界坡降和破坏坡降,其与层间系数近似呈负相关关系,层间系数越小,潜蚀发生的临界坡降和破坏坡降越大。层间系数对双层地基颗粒运移模式及破坏模式均有显著影响。层间系数≤5时,下层土体中运移流失的细颗粒聚集、淤堵在接触面,最终导致接触面附近出现明显的拉裂破坏;层间系数>5时,上层土体不能有效保护下层土体,下层土体中运移出来的细颗粒大量进入上层,最终下层土体发生潜蚀破坏。基于试验结果,提出了适用于被保护土体为内部不稳定土的反滤层设计方法,并利用已有的试验结果验证了该方法的有效性和可靠性。Geological structure significantly influences the evolution of suffusion in alluvium foundations,and then may affects the safety of dams.However,the present studies mainly focus on the internal instability and hydraulic conditions initiating suffusion of the internally unstable soils,and the influence of geological structure is neglected.A series of transparent suffusion tests on double-layered foundation were carried out by a new suffusion visualization apparatus based on planar laser induced fluorescence technology.In the double-layered foundation,the upper and lower soil layers serve as filter and base soil,respectively.The influence of retention ratio of double-layered soil on the evolution of suffusion was investigated.The results indicate that the upper soil layer has a remarkable influence on the critical hydraulic gradients at the initiation of suffusion and at blowout.The critical hydraulic gradients decrease with the increase of the retention ratio.The retention ratio significantly influences the fine particle migration and failure modes.If the retention ratio is less than or equal to 5,the eroded fine particles from the lower soil layer were clogged at the interface,and eventually induces tensile failure;if the retention ratio is larger than 5,the upper soil layer can¢t effectively protect the lower soil layer,the fine particles from the lower soil layer were eroded into the upper soil layer,and then pass through the layer,and eventually induce suffusion failure.A new filter criterion for the internally unstable base soils was proposed,and then it was validated by the experimental results presented in reference.

关 键 词：土力学 深厚覆盖层 双层地基 潜蚀 可视化 层间系数 反滤设计方法 

分 类 号：TU443[建筑科学—岩土工程]