列车环境振动扰动下浅表土洞型岩溶塌陷的动力学机制研究

The influence of karst collapse geological hazards on railway engineering runs through the whole stage of railway construction and operation, and has the characteristics of concealment, periodicity and abruptness. Train vibration is an important inducement for karst collapse. This project closely combines disaster mitigation, disaster prevention and safety operation requirements of railway projects in Karst areas, taking the dynamic and collapse mechanism of karst surface subsidence under the disturbance of train environmental vibration as the research objectives. Typical karst collapses in environmental vibration field along Guilin-Hezhou section of Guizhou-Guangzhou high-speed railway and Guizhou-Zhangzhou-Changzhou railway are selected as research objects. Focusing on the variation law of water pressure in karst pipeline system in environmental vibration field and the dynamic mechanism of karst soil cave development-expansion-collapse under coupling action, field investigation, site vibration monitoring, vibration- geomechanics modeling, soil dynamic triaxial test and micro-tests, physical model tests, dynamic monitoring, numerical simulation and theoretical research are adopted to explore the dynamic mechanism, evolution law and relationship model of karst collapse under the action of train environmental vibration and groundwater, which provides scientific basis for the safe operation of railway in karst areas and the disaster prevention and mitigation of karst collapse in China.

岩溶塌陷地质灾害对铁路工程的影响贯穿铁路建设运营全阶段，具有隐蔽性、周期性和突发性等特点。列车振动是导致岩溶塌陷的重要诱因，本项目紧密结合岩溶区铁路工程减灾防灾和运营安全需求，以列车环境振动扰动下浅层地表岩溶塌陷的动力学机制和致塌机理为研究目标，选择贵广高铁桂林-贺州段和黔张常铁路沿线环境振动场典型岩溶塌陷为研究对象，围绕环境振动场岩溶管道系统水气压力变化规律和振动与地下水耦合作用下岩溶土洞发育-扩张-塌陷动力学机制等问题，采用现场勘察、场地振动监测、振动场-地质力学建模、土动三轴和微观试验、物理模型试验、动态监测、数值模拟和理论研究等研究方法，探索列车环境振动和地下水作用下岩溶塌陷的动力学机制、演化规律和关系模型等，为我国的岩溶区铁路的运营安全和岩溶塌陷的防灾减灾提供科学依据。

列车振动是导致岩溶塌陷的重要诱因，本项目紧密结合岩溶区铁路工程减灾防灾和运营安全需求，以列车环境振动扰动下浅层地表岩溶塌陷的动力学机制和致塌机理为研究目标，选择贵广高铁桂林-贺州段和黔张常铁路沿线环境振动场典型岩溶塌陷为研究对象，明确了典型铁路工程线路潜在的岩溶塌陷的岩土结构模型，分析了典型塌陷区的研究区的岩溶地质结构、岩土空间分布结构及地下水空间分布特征；开展了列车振动下岩溶区场地振动信号数据的现场采集试验，分析了列车振动波在周边岩溶系统和土层中的传播规律，建立了列车环境振动下土洞型浅表岩溶塌陷的地质力学模型；开展了考虑时间间歇效应的动三轴试验、循环荷载下岩土体的微观特性试验，建立了岩溶塌陷区土体的微观结构特性和宏观力学参数之间的关系；设计了以地表降雨、地下土壤含水率、地下孔隙水压力、土压力为监测指标，提出了岩溶土洞致灾阈值与综合判据，确定了列车振动影响下岩土体强度衰减规律与地表塌陷关系；完善了室内模型试验的物理空间模型，结合数值模拟分析了列车振动作用下土层发生岩溶塌陷全过程的内部结构变化特征；研究了不同振动频率、振源位置和地下水位变化条件下发生塌陷土体结构和强度变化特性，揭示了列车环境振动与地下水耦合作用土洞的发育-扩张-塌陷形成动力学机制研究，研究成果为我国的岩溶区铁路的运营安全和岩溶塌陷的防灾减灾提供科学依据。