高压透水隧洞变形协调与水力传递机制研究

Inner water exosmosis is one of the most prominent characteristics of high pressure tunnels under operation condition, which has marked influence on the tunnel structure safety and the slopes stability upon the tunnel. The composite methods with indoor experiment, local measurement, theoretical analysis and numerical simulation are employed to study the mechanisms of deformation compatibility and hydraulic transmission for the pervious tunnels. And the patterns of concrete crack propagation and distribution will be analyzed along with the tunnel liner indoor experiment loaded directly by inner water pressure. And the concrete crack numerical model will be developed while the calculation methods of crack width with water injected and rock mass deformation capability are concluded. The spatial surfaces of cracks and the basement surfaces to estimate roughness are built up with laser scanning method and spatial imaging technology after the characteristics of roughness and tortuosity along the crack surface are analyzed. Then the calculation methods of the permeability of cracked concrete liner are furnished, in which crack width, crack surface characteristic, reinforcement layout and hydraulic condition are considered, to analyze the mechanism of hydraulic conduction when the tunnel liner is fully cracked. Furthermore, the joint element model with a special function is developed to simulate the combined capability of concrete liner and surrounding rock along the surface between them. The dynamic combination status between liner and surrounding rock and the distribution of water pressure around tunnel are analyzed after the combined bearing model including liner, joint and rock mass are built up. The mechanisms of deformation compatibility and hydraulic transmission between rock mass and liner are discussed in the end. And the outputs could reveal the inherent bearing mechanism of pervious tunnel, which could provide primary guarantee for the tunnel safety.

透水是高压水工隧洞的突出特征，是影响隧洞结构安全与沿线山体稳定的关键因素。本项目拟采用理论分析、室内试验、原型观测与数值模拟相结合的方法，研究高压隧洞透水过程中的变形协调与水力传递机制。.开展衬砌室内压水试验，分析隧洞充水环境下的混凝土裂缝扩展与分布特征，建立基于围岩变形能力与隧洞充水环境的混凝土裂缝宽度计算方法，构建衬砌混凝土裂缝模型；分析混凝土裂缝表面粗糙度与迂曲度特征，研究基于激光扫描与三维成像技术的混凝土裂缝表面和粗糙度评价基准面生成方法，完善考虑裂缝宽度、表面特征、布筋环境和水力条件的开裂混凝土衬砌的渗透系数计算方法，揭示开裂混凝土衬砌的水力传导机制；依托衬砌与围岩结合面构造接缝单元，组建基于衬砌-接缝单元-围岩的水工隧洞组合承载模型，研究高压隧洞水力变化特征以及衬砌与围岩间的动态结合状态，揭示衬砌与围岩间的变形协调与水力传递机制。研究成果可为高压透水隧洞的安全运行提供重要保证。

本项目针对衬砌混凝土裂缝模型、开裂混凝土衬砌内水外渗水力传导机制、衬砌与围岩联合承载机理等三个方面展开研究。采用塑性损伤模型模拟衬砌裂缝，将开裂破坏这一非连续的脆性结构响应问题通过等效损伤来体现，实现了非连续断裂的等效连续化。提出透水衬砌渗流-应力-损伤耦合模型，基于ABAQUS软件平台进行二次开发， 实现材料渗透系数随损伤的动态更新，完成了隧洞动态充水过程中的衬砌损伤开裂耦合分析过程，探讨了衬砌与围岩有条件联合承载特性对耦合分析结果的影响。同时，采用cohesive单元模拟水力裂缝，考虑裂缝与岩体水体交换特性，以及岩体弹塑性变形特征，建立应力-渗流-损伤耦合非连续性模型，探讨了水力裂缝起裂与扩展过程中水压力的分布规律。针对高压隧洞透水衬砌结构，考虑衬砌与围岩间的粘结力作用，建立了双层厚壁圆筒模型，提出了相应的透水衬砌设计方法与实践步骤，分析了隧洞初次充水期间衬砌与围岩的有条件联合承载机理，并重点分析了钢筋应力、最大裂缝宽度等的演化规律，提出了由开裂点及脱离点控制标示的衬砌钢筋应力的三段式计算模型，揭示了初次充水过程中衬砌与围岩脱离前是钢筋应力峰值点的这一新规律，为工程安全和运行决策提出了强有力的技术支撑。同时，系统研究了渗流与应力数值计算过程中计算模型范围对计算结果与误差的影响分析，提出了渗流、应力计算过程中的模型范围取值方法。