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为研究岩溶地区隧道开挖过程中,充填型岩溶管道受施工扰动和地下水渗流作用发生失稳突水的机制,以湖北省保康—宜昌高速公路尚家湾隧道突涌水段为工程背景,通过大型三维可视化固–液耦合试验平台、水压加载控制系统以及水压环境下有较好相似度的流–固耦合岩石和充填物相似材料的研制,开展深长隧道充填型岩溶管道渗透失稳突水的大比尺三维流–固耦合模型试验,真实再现隧道开挖和水压加载过程中,岩溶管道充填物中裂隙形成→扩展→导水通道贯通→突水的全过程,通过位移、应力和渗压变化规律的分析,揭示充填物渗透失稳突水过程的灾变演化机制。试验结果表明:(1)施工过程中充填型岩溶管道突水是开挖扰动和高地下水位高渗透力作用诱发充填物渗透失稳的结果;(2)充填物受开挖扰动影响比围岩更明显,变形量比围岩大20%~25%,应力释放率比围岩高30%;水压加载阶段,水头高度升高到6.0 m时,充填物位移突增50%,渗压下降速率达0.6k Pa/min,达到失稳临界状态;(3)岩溶管道突水受其发育形态影响比较明显,其弯曲角度较大的部位是阻碍上部水和充填物突出的主要屏障;(4)充填型岩溶管道渗透失稳突水的灾变演化过程经历4个阶段:形成离散的微小裂隙、裂隙连通形成导水通道、在渗流作用下导水通道扩展延伸、导水通道贯通形成突水路径,其中前2个阶段主要受开挖扰动影响,后2个阶段与高水位高水压的渗流作用密切相关。试验成果对突涌水机制的研究和工程中突涌水灾害的防治具有一定的指导意义。
In order to study the mechanism of instability and water inrush caused by construction disturbances and groundwater seepage during the process of tunnel excavation in karst areas, the paper takes the water inrush of Shangjiawan tunnel of Baokang-Yichang Expressway in Hubei Province as an example, Large-scale three-dimensional visualization of solid-liquid coupling test platform, water pressure control system and the water pressure environment has good similarity of fluid-solid coupling rock and filling materials similar to the development of deep tunnel filled karst pipeline infiltration destabilization Water large-scale three-dimensional flow-solid coupling model test to truly reproduce the process of tunnel excavation and hydraulic loading, the filling of karst pipe fissures in the formation → expansion → water channel through water → water inrush through the entire process of displacement, stress And seepage pressure variation analysis to reveal the filling infiltration instability water burst disaster evolution mechanism. The results show that: (1) The water inrush of filling karst pipeline during excavation is the result of seepage instability caused by excavation disturbance and high permeability of groundwater table; (2) More obviously, the deformation is 20% -25% larger than the surrounding rock, and the stress release rate is 30% higher than the surrounding rock. When the water pressure increases to 6.0 m, the displacement of the filling suddenly increases 50% and the seepage pressure drops (3) Karst pipe water inrush affected by its developmental morphology is obvious, its bending angle is a major obstacle to the upper water and filling the main barrier of the prominent; (4) ) The catastrophic evolution process of infiltration instability and water inrush of filling karst pipeline goes through four stages: formation of discrete tiny cracks, the connection of fissures to form a water-conducting channel, the water-conducting channel expands and extends under seepage and the water-conducting channel penetrates to form a water inrush path , Of which the first two stages are mainly affected by excavation disturbances. The latter two stages are closely related to the seepage action of high water pressure and high water pressure. The result of the experiment is of guiding significance to the study of water inrush mechanism and prevention and treatment of inrush water disaster in engineering.