海水侵蚀环境影响下海底隧道浆-岩复合体弱化机理研究

Subsea tunnels often encounter weak and broken rock masses with complex engineering properties, and that are more susceptible to collapse, groundwater and mud inrush. To deal with these unfavorable conditions, the grouting method has been widely used to enhance the mechanical properties of weak rock masses. Unfortunately, the current understanding of grouting mechanism and grout-rock complex weakening mechanism under seawater erosion are very limited. By adopting the methods of theoretical derivation, laboratory test, model test and numerical simulation, this project intends to reveal the weakening mechanism of grout-rock complex under seawater ions and water pressure erosion, also the resisting weakening mechanism of grouting. On basis of simulating the grouting process under high injection pressure and water pressure, the typical grouting reinforcement mode can be obtained. Considering the erosion effect of seawater ions and water pressure, this study focuses on the physical and chemical damage of grout-rock complex microscopically, therefore the quantitative characterization method of damage could be proposed. In addition, the influence of seawater ions concentration, water pressure and curing age on mechanical properties of the complex, as well as the relationship between microscopic damage and macroscopic properties weakening, will be studied. Therefore, the weakening model of grout-rock complex mechanical properties could be developed. On the basis of revealing the resisting weakening mechanism of grouting, the method for resisting weakening of complex mechanical propertie under seawater erosion will be proposed. The conclusions can provide theoretical guidance for grouting design in subsea tunnels, also can contribute to the safety construction and operation of the subsea tunnels.

海底隧道穿越软弱破碎岩体易诱发垮塌和突水突泥灾害，注浆技术是防渗和加固的首选途径，但考虑海水环境影响的注浆机理及浆-岩复合体性能弱化规律等方面的研究尚不成熟，亟待加强。本项目综合采用理论分析、室内试验、模型试验和数值模拟相结合的研究方法，重点揭示海水侵蚀环境对于浆-岩复合体力学性能的弱化规律及注浆抑制机理。在还原海底水压力和浆-岩复合体高压胶结环境的基础上，确定注浆典型加固模式；模拟海水离子和水压力侵蚀环境，揭示侵蚀作用下复合体损伤物理和化学本质；获取海水离子浓度、水压力和养护龄期对于复合体力学性能的弱化规律，揭示复合体微观损伤与宏观性能弱化之间的关联机制，建立侵蚀作用下复合体力学参数弱化模型；分析注浆加固效应对于侵蚀弱化的抑制机理，提出侵蚀环境下海底隧道浆-岩复合体性能弱化抑制方法。研究成果可为我国海底隧道地质灾害注浆防控提供理论支撑，保障海底隧道建设顺利进行和长期运营安全稳定。

海底隧道建设穿越强风化带和节理裂隙发育带等软弱破碎岩体易诱发地质灾害，注浆技术可实现岩土体防渗与加固，但目前在海水环境对于浆液性质的影响、考虑浆-岩耦合作用的浆液扩散机理、动态侵蚀海水环境对于浆-岩复合体的弱化机制等方面研究尚不成熟。本项目综合采用理论分析、室内试验和数值模拟相结合的研究方法，聚焦“海水环境下水泥基浆液及浆-岩复合体基础性能”、“海水环境影响下海底隧道强风化带注浆扩散机理”和“动态海水环境下海底隧道强风化带浆-岩复合体弱化机理”三方面研究内容，实现了考虑海水环境影响的注浆扩散机理与浆-岩复合体性能弱化规律的关联性研究。获取了海水环境下典型浆液的黏度时变规律，划分了黏度时变的典型阶段，拟合了浆液黏度时变方程，对比了海水环境与淡水环境下浆液黏度时变规律。提出了多序注浆影响下被注介质压缩模型和劈裂扩展模型动态演变机制，揭示了关键注浆参数对于多序注浆浆液劈裂过程的影响规律；考虑裂隙倾角以及粘度时空分布规律的影响，建立了水泥基浆液在海底隧道裂隙岩体中的扩散模型，获得了关键参数计算方法，揭示了浆液扩散机理。自主设计并研制了模拟海水流动特性的试验装置，可实现侵蚀参数精确控制；根据Arrhenius方程化学反应速率原理，通过提高溶液浓度与温度加速离子侵蚀，获取了海水侵蚀环境对浆-岩复合体的弱化规律；通过控制侵蚀溶液离子种类与复合体试件侵蚀条件，揭示了动水环境、注浆压力、水灰比、服役时间等关键因素对于浆-岩复合体性能弱化的影响规律；结合微观观测方法，揭示了复合体侵蚀弱化机理，确定了侵蚀弱化关键抑制因素。研究成果可为我国海底隧道地质灾害注浆防控提供理论支撑，保障海底隧道建设顺利进行和长期运营安全稳定。