基于模型试验的阻-透型岩溶塌陷演化过程与机理研究  

Development process and mechanism of sinkhole with upper clayey and lower sandy layer cover based on model tests

作　　者：王英 肖先煊[1] 许模[1] WANG Ying;XIAO Xianxuan;XU Mo(State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059

出　　处：《铁道科学与工程学报》2024年第11期4815-4826,共12页Journal of Railway Science and Engineering

基　　金：四川省科技计划项目(2021YJ0320)。

摘　　要：地下水位下降是诱发地面塌陷的关键因素之一。为研究地下水位下降触发岩溶地面塌陷的过程和机理,以塌陷区上阻下透结构盖层(上层为黏性土、下层为砂性土)的典型塌陷坑为研究对象,通过室内土工试验获取了盖层土体的物理力学性质和水理性质参数,并在室内构建地质物理模型,设计符合现场实际的5组试验工况,探讨不同排水速率条件下的溶洞内真空负压变化与盖层表面变形的本质关系。基于极限平衡理论分析盖层的受力特征,提出盖层稳定性的判别模型。并利用判别模型对物理模拟试验结果进行验证,显示两者总体吻合。研究结果表明:1)盖层表面变形、塌陷与溶洞内地下水位下降速率关系密切。当盖层处于塌陷临界状态时,溶洞内真空压强到达峰值,地下水位下降速率到达谷值,孔隙水压力出现“倒V形”曲线段。2)地下水位下降产生的渗透压力、真空吸蚀力是触发此类岩溶地面塌陷的关键因素,控制着盖层的变形和演化行为。3)致塌力、抗塌力均随地下水位的下降而增大,当地下水位的初始下降速超过临界值8.9×10^(-3)m/s时,产生的致塌力超过抗塌力,塌陷发生。塌陷演化过程总体可划分为盖层逐渐向下变形和突然失稳塌陷2个阶段。研究成果具有一定合理性和参考意义,可为塌陷区防灾减灾工作提供重要技术支撑。Decline in water levels is one of the key factors inducing sinkholes.In order to better understand the cover collapse sinkhole process and disaster-causing mechanism,this article selected a typical sinkhole with upper clayey and lower sandy layer cover in collapse area as research object,obtained the mechanical parameters and hydraulic property parameters of cover soil.And then 5 physical model tests were carried out in accordance with the field situation for discussing the essential relationship between the negative pressure in cave and the surface deformation of cover under different drainage rates.Moreover,based on the limit equilibrium theory,a suitable stability discrimination model was proposed for verifying the results of physical model tests,which were generally consistent with each other.On this basis,the critical rate of groundwater level decline was determined.Our research indicates that(1)The cover surface deformation and collapse are closely related to the fall rate of decline in water level.When the cover is in the critical state of collapse,the vacuum pressure in the cave reaches the peak value,the rate of decline in water level reaches the trough value,and the pore water pressure appears an“inverted V-shaped”curve section.(2)The osmotic pressure and vacuum suction caused by water level decline are the key factors that trigger the sinkhole collapse and control the deformation and evolution behavior of the cover.(3)Both the collapsing force and the anti-collapsing force increase with the decline in groundwater level.if the initial rate of decline in water level exceeds the critical value 8.9×10^(−3) m/s,the collapsing force can exceed the anti-collapsing force and then cover collapse sinkhole occurred.And the collapse process of cover is divided into two stages,which are the gradual downward deformation and sudden instability collapse.The research results can have certain rationality and reference significance and can provide important technical support for disaster prevention and reduction i

关 键 词：阻-透型盖层 地下水位下降 物理模拟试验 判别模型 岩溶塌陷机理 

分 类 号：P641[天文地球—地质矿产勘探] P642.25[天文地球—地质学]