基于颗粒流的覆盖型岩溶地面塌陷动态演化特征研究  

Dynamic evolution characteristics of ground collapse of covered karst based on particle flow

作　　者：师海 贾智磊 白明洲[1,3] 张晔 孙子冰 SHI Hai;JIA Zhilei;BAI Mingzhou;ZHANG Ye;SUN Zibing(School of Civil Engineering,Beijing Jiaotong University,Beijing100044,China;Beijing Key Laboratory of Track Engineering,Beijing 100044,China;Beijing Engineering and Technology Research Center of Rail Transit Line Safety and Disaster Prevention,Beijing 100044,China)

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]轨道工程北京市重点实验室,北京100044 [3]北京市轨道交通线路安全与防灾工程技术研究中心,北京100044

出　　处：《中国岩溶》2024年第5期1110-1120,共11页Carsologica Sinica

基　　金：国家自然科学基金项目(41907260、42172311);中央引导地方科技发展资金项目(216Z3802G)。

摘　　要：为揭示铁路周边覆盖型岩溶土洞扩展的动态演化规律和细观致塌机理,以京沪高铁(江西段)某典型岩溶塌陷点为依托,通过颗粒流(PFC^(2D))压缩试验对塌陷土体的强度参数进行标定,引入接触黏结模型,建立覆盖型岩溶地面塌陷流固耦合模型,从细观角度揭示了岩溶地面塌陷的动态演化过程与变形特征,探究不同溶洞开口大小、覆盖层厚度、地下水位高度对覆盖型岩溶地面塌陷变形特征的影响。研究表明:地表沉降、土体孔隙率等随塌陷演化发展而逐渐增大;地下水位高度越高,土洞扩展越快,地表沉降越明显,塌陷也越易发生;溶洞开口越大,地面沉降深度和范围随之增大,塌陷越易发生;覆盖层厚度越小,地表沉降变化越明显;从细观角度可知,塌陷过程中颗粒间接触力变化过程近似为“应力平衡-应力拱形成-应力拱破坏-应力再次平衡-…-应力拱断裂”的规律。研究从细观角度揭示了岩溶地面塌陷演化的全过程,可为高速铁路建设、运营期周围环境覆盖型岩溶地面塌陷的防灾减灾提供参考。Karst collapse represents a significant geological hazard,predominantly occurring in regions characterized by the presence of soluble rock formations,including carbonate rocks,calcareous clastic rocks and salt rocks,among others.The characteristics of karst collapse fall into three key attributes:a hidden spatial distribution,a sudden occurrence and a periodic recurrence over time.These attributes can collectively challenge the construction of major infrastructure in karst areas.A karst collapse disaster along the railway will potentially pose a significant threat to the safe construction and continued operation of the high-speed railways.During both the construction and operational phases of railways in karst areas,pumping and discharging groundwater,along with altering hydrodynamic conditions,have been identified as key factors contributing to karst collapse.The most widely used numerical simulation method is the finite element method(FEM),which is based on the assumption of a continuous medium.FEM simplifies a complex problem by breaking it down into more manageable components.It conceptualizes the solution domain as a collection of small interconnected sub-domains called finite elements.For each element,a suitable(simpler)approximate solution is assumed,and the conditions necessary for solving the overall domain are derived.However,soil is not a continuous medium;therefore,a model based on FEM is unable to simulate the local instability of a collapsed soil body,the damage process at a mesoscopic scale,and other phenomena.In light of the dearth of sufficient attention to the temporal effects and fine-scale mechanisms of the karst collapse process in current studies,this paper aims to elucidate the dynamic evolution laws and mesoscopic-scale collapse mechanisms of the expansion of overlying karst soil caves around the railway.A typical karst collapse site,namely the Beijing–Shanghai high-speed railway(Jiangxi section),was selected as the basis for calibrating the strength parameters of the collapsed soil body

关 键 词：覆盖型岩溶 土洞扩展 颗粒流 数值模拟 动态演化 

分 类 号：P642.5[天文地球—工程地质学]