华南富水全强风化花岗岩隧道突水突泥动力学演化与致灾机理研究

Water-rich completely and strongly weathered granite is widely distributed in southern China, tunnel excavations in those areas often suffer serious water and mud inrush disasters due to its special engineering behaviors of low strength, strong disintegration, and bad water stability. Thus, there is an urgent need to carry out the research of water and mud inrush mechanism in completely and strongly weathered granite. This program intends to use field investigation, laboratory model tests to study the evolution process of water and mud inrush under the coupled effects of water pressure and earth pressure, to reveal the key factors, disaster characteristics and evolution mechanism of water inrush channel based on the consideration research of variable mass behavior and flow pattern transformation behaviors, and to establish the seepage-stress-erosion coupling water and mud inrush model considering the mass transfer and flow pattern transformation behaviors. Simultaneous, constructing the numerical simulation software by secondary development to solve the theoretical model. Then, the numerical method will be used to study the water inrush evolution process, to establish the water inrush disasters criteria combining with laboratory model tests and field tests. The research results of program could provide scientific basis and theoretical foundation for comprehensive prediction, early warning and process control of water and mud inrush for completely and strongly weathered granite tunnel.

全强风化花岗岩广泛分布于我国华南地区的浅中地层，因其软弱、崩解性强、水稳性差，在富水地区开挖隧道时常易导致严重的突水突泥灾害。因此，开展此类地层的突水突泥动力学演化过程及其致灾机理研究极为迫切和关键。本项目拟通过开展现场调查、室内突水突泥模型试验，研究高水压地应力耦合作用下的突水突泥灾变演化过程，在充分研究灾变的变质量特征及流态转换特性的基础上，揭示突水通道形成的主控因素、临灾特征及其演化机理，并结合理论分析建立可考虑质量迁移与流态转换的变质量渗流-应力-侵蚀耦合的突水突泥模型。以实际工程为依托，通过二次开发构建数值仿真程序，实现灾变动力学演化的全过程模拟，并综合室内试验与现场试验数据构建突水突泥临灾判据。本项目研究成果可为富水全强风化花岗岩隧道突水突泥的预测、预警、过程控制及防治提供科学依据和理论基础。

在我国华南全强风化花岗岩地层修建隧道时，突水突泥地质灾害给隧道安全建设带来极大技术挑战。通过自主研发的大型动水三轴模型实验系统，本项目试验研究高水压地应力耦合作用下的突水突泥灾变演化过程。在考虑岩土体颗粒迁移及渗流流态转换特征下，探究了不同试样级配、初始孔隙率、不同应力条件下的突水突泥演化过程，得到了关键的灾变条件。在理论模型层面，结合溶质运移、多孔介质渗流力学等理论建立了变质量渗流应力侵蚀耦合模型，提出了非线性渗流模型，考虑质量迁移的孔隙率演化模型，渗透率-孔隙率演化模型以及颗粒运移模型。为了实现灾害的模拟，以Comsol多场耦合系统为平台，将构建的理论模型进行离散求解，进而构建有效的仿真技术，以实现突水突泥灾害全过程模拟。最后，采用实际现场隧道突水突泥灾害数据对项目研究成果进行验证及优化。项目的研究成果进一步完善突水突泥地质灾害预测及防控技术。