基于海水劣化作用的断层破碎带注浆加固机理及长期稳定性研究

Currently, the grouting method for fault fractured zone of subsea tunnel is borrowed from that of mountain tunnel construction, which overlooks the influence of chemical erosion and seepage force on grouting process, and is not sufficient for long-period safety of construction. In this research, based on analyzing research status in our country and overseas, various research methods are used for investigation, such as theoretical analysis, numerical simulation, laboratory test, model test and field test. Firstly, a discrete-continuum coupled mechanical model is proposed based on the non-continuum and inhomogeneous property, to study the influence of grout vein structure and the cementation force on grouting interface, and to reveal the mechanism of grouting reinforcement of fault fractured zone. Then, the influence of ion erosion and seepage force, and their coupling effect are revealed with consideration of seawater condition. The time decreasing factor of grout reinforced body is established and a time prediction model for strength decreasing degree is proposed. Finally, a creep deformation model of surrounding rock is proposed with consideration of crustal stress, seepage force and ion erosion. A critical value of grouting reinforcement and a security factor are proposed for long-period safety of subsea tunnel and field tests are carried out to test and improve the research results, to minimize engineering disasters and accidents, and enhance the construction safety and disaster prevention ability, which is of great theoretical and practical meaning.

目前海底隧道破碎带注浆加固理论和设计方法多参考陆域隧道，较少考虑海水离子侵蚀和长期渗流的影响，难以满足工程长寿命安全需求。本项目在分析国内外研究现状基础上，拟运用理论分析、数值模拟、室内试验、模拟试验及现场试验相结合的方法开展研究：首先，充分考虑断层破碎带非连续、非均质特性，建立断层破碎带离散-连续耦合力学模型，分析注浆界面胶结与浆脉骨架支撑及其共同作用机制，揭示断层破碎带注浆加固机理；其次，研究并揭示海水条件下，破碎带注浆加固体在离子侵蚀、长期渗流及其耦合作用下的劣化机制，获得加固体强度的时间劣化因子，建立其强度劣化的时间预测模型；最终，建立考虑地应力、渗透压力、离子侵蚀劣化作用下的围岩蠕变模型，提出满足海底隧道长寿命安全的注浆加固临界力学指标与安全系数，并通过现场试验进行研究成果的验证和完善。研究成果对于控制海底隧道重大工程灾害的发生，保障工程长寿命安全具有重大的理论和实践价值。

本项目围绕海水劣化作用下的断层破碎带注浆加固机理和长期稳定性等关键科学问题，开展了大量研究工作，按时完成了项目任务书规定的各项任务。在海底隧道断层破碎带注浆加固机理、海水条件下破碎带注浆加固体强度劣化机理和断层破碎带变形机制与隧道长期稳定性等方面取得了重要进展，主要如下：. （1）针对典型围岩试样开展三轴试验，建立了海底隧道断层破碎带岩体本构模型。建立了张性与剪性注浆充填结构面的剪切力学分析模型，揭示了注浆充填结构面的剪切破坏机制与注浆加固机理。建立了断层破碎带加固体强度表征方法，揭示了断层破碎带注浆加固机理。. （2）分析总结了断层破碎带加固体在海水环境条件下力学强度的长期变化规律，揭示了离子浓度、侵蚀时间对注浆加固体强度的长期劣化机制。明确了化学侵蚀与长期渗流耦合作用下注浆加固体强度的衰减规律和劣化机制，获得了加固体强度的时间劣化因子，建立了其强度劣化的时间预测模型。. （3）建立了加固体损伤演变方程及损伤数学模型，揭示了海洋环境下围岩的长期变形机制。提出了满足海底隧道长寿命安全的注浆加固临界力学指标与安全系数，形成了海水环境下断层破碎带注浆设计方法。. 以上研究成果已在国内外学术期刊发表论文12篇，授权发明专利5项，相关成果在青岛地铁1号线、8号线海底隧道和胶州湾二隧工程中推广应用，保障了隧道的顺利贯通，对隧道安全建设与运营发挥了重要作用。