深埋软岩隧洞围岩-衬砌协同承载体系变形破裂演化机制与自适应数值流形方法

The lining structure of deep-buried and soft rock tunnel needs to bear partial pressure caused by surrounding rock squeezing deformation. Damage degradation of lining structure will be induced by the pressure, such as cracks, which causes hidden danger of the long-term operation of tunnels. For this reason, using the methods of theoretical analysis, experiments and numerical simulation, crack propagation criteria for joint bearing system of surrounding rock and lining in deep-buried and soft rock tunnel and algorithms such as search of fracture elements, generation of new cracks, and physical cover renewal during crack propagation will be studied and a numerical manifold method for simulating the crack propagation process will be established. With regard to the characteristics of discontinuity and singularity after fracture of the joint bearing system of surrounding rock and lining, high-order displacement function with high accuracy, efficient local mesh refinement algorithm and posteriori error estimation will be studied in numerical manifold method, and an adaptive numerical manifold method program will be developed. Then the joint bearing characteristics, influence factors and interaction laws of surrounding rock and lining will be clarified, and the whole fracture process of joint bearing system for surrounding rock and lining in deep-buried and soft rock tunnel will be revealed. The research results have important theoretical significance for understanding the fracture evolution law of joint bearing system for surrounding rock and lining. Meanwhile, the results can provide theoretical basis and technical guidance for the stability evaluation of the joint bearing system for surrounding rock and lining.

深埋软岩隧洞的衬砌结构需要承担部分来自围岩挤压变形带来的压力，存在诱发衬砌结构产生裂缝等损伤劣化的可能，对隧洞长期运行带来安全隐患。为此，采用理论分析、室内试验与数值模拟相结合的方法，研究围岩-衬砌协同承载体系裂纹扩展准则，提出破裂单元检索、新生裂纹生成及裂纹扩展过程中物理覆盖更新等算法，建立模拟裂纹扩展过程的数值流形方法；针对围岩-衬砌协同承载体系开裂后的非连续性和奇异性特点，研究数值流形方法中具有高精度的高阶位移函数、高效的局部网格加密算法及后验误差估计，开发自适应数值流形方法程序；阐明围岩-衬砌协同承载特征、影响因子及其相互作用规律，揭示深埋软岩隧洞围岩-衬砌协同承载体系由连续到非连续变形破裂演化机制。研究成果对认识深埋软岩隧洞围岩-衬砌协同承载体系变形破裂演化规律具有重要的理论意义，可为软岩隧洞围岩与衬砌结构联合受力的稳定性评价提供理论基础和技术指导。

深埋软岩隧洞衬砌结构在隧洞施工、运营过程中，往往会产生裂缝等损伤劣化现象，为隧洞的安全性带来隐患。为此，项目以深埋软岩隧洞围岩-衬砌协同承载体系为研究对象，围绕表征裂纹扩展演化的数值流形模型、高精度高效率的自适应数值流形方法、围岩-衬砌协同承载体系变形破裂演化机制等研究内容，通过理论分析、数值模拟、室内试验及原位测试和监测等多种手段开展了相关研究工作。采用最大周向应力准则作为深埋软岩隧洞围岩-衬砌协同承载体系的裂纹扩展准则，并相应提出了数值流形方法中破裂单元检索、新生裂纹生成及裂纹扩展过程中物理覆盖更新等算法，将上述建立的围岩-衬砌协同承载体系裂纹扩展失稳准则嵌入到数值流形方法中，实现了裂纹扩展过程中数值流形方法模拟的自动控制。将B样条基函数作为数值流形方法中的权函数，建立了高阶数值流形方法的分析格式，实现了数值流形方法中的p型自适应策略。推导了不同阶次的适合分析T样条的基函数，并将其作为数值流形方法中的权函数，针对性的，提出了一种基于适合分析T样条的自适应局部网格加密算法，实现了数值流形方法中的h型自适应策略。通过现场综合测试和监测、围岩-衬砌结构联合承载的仿真试验、数值仿真等多种手段，揭示了深埋软岩隧洞围岩-衬砌协同承载体系由连续到非连续变形破裂演化规律、影响因子及相互作用机制。所建立的数值分析方法及揭示的规律机理在天山隧洞、圣佳旺水电站引水隧洞等深埋软岩隧洞工程中得以应用，为工程优化设计和安全施工发挥了积极的支撑作用。