TBM滚刀作用下岩石密实核动态衍生机制及刀岩界面接触力特性研究

The crushed zone phenomenon affects the rock-breaking mechanism of TBM disc cutters, resulting in the discontinuous-concentrated distribution of contact forces at the interface between the cutters and rock. This interaction mechanism seriously shortens the life of cutters, but has not yet been quantitatively studied. In this project, methods of numerical simulation, experiments and theoretical analysis are integratedly used to study the dynamic growth mechanism of the zone under the action of the cutters, and then its influence on rock crack propagation and contact force characteristics are further discussed. Firstly, in order to reproduce the growth process, three-dimensional rock-breaking models of the cutter are established by using overlapping nodes method; at the same time, in-situ/off-line observation test schemes are proposed, and the contact force test scheme based on TSVD is given by reliably solving an influence function. Secondly, characterization methods of the macroscopic morphology and its characteristic parameters are given; the spatiotemporal evolution law of the characteristics is studied and the periodic concentration-scatter law of crushed materials is then revealed. In addition, the materials/energy dissipation characteristics during rock powder splitting processes are studied, and the rock crack propagation mechanism powered by the zone is obtained. Finally, the contact force characteristics of the cutter are explored to reveal its essential relations with the aforementioned spatiotemporal evolution law and the aforementioned periodic concentration-scatter law; based on cavity expansion theory and elastoplastic theory, the nonlinearities of the interface and materials are considered; Then disc cutter-crushed zone interaction models are established which provides a theoretical basis for the design and manufacture of long-life cutters.

密实核现象影响了滚刀破岩机理，并导致刀岩界面接触力非连续集中分布，严重缩短了滚刀使用寿命，而目前尚未对此加以定量研究。本项目拟采用仿真、试验和理论相结合的手段，对TBM滚刀作用下密实核动态衍生机制展开研究，探讨其对岩石裂纹扩展和接触力特性的影响规律。首先，为了再现密实核衍生过程，基于重合节点法建立滚刀三维破岩模型，同时提出原位/离线观测试验方案，并给出TSVD可靠求解影响函数的接触力测试方案；其次，提出密实核宏观形态特征表征方法及其特征参数，研究所述特征时空演化规律，揭示密实核物质周期性聚集溃散规律；此外，研究粉劈过程中物质/能量耗散特性，揭示密实核作用下裂纹扩展机制；最后，探究刀圈接触力特性，揭示其与所述时空演化规律和所述物质周期性聚集溃散规律间的本质联系，并基于腔体膨胀理论和弹塑性理论，推导考虑所述界面非线性和材料非线性的滚刀-密实核相互作用模型，为设计制造长寿命滚刀提供理论依据。

密实核现象影响了滚刀破岩机理，并导致刀岩界面接触力非连续集中分布，严重缩短了滚刀使用寿命，而目前尚未对刀岩作用过程中的密实核现象加以定量研究。本项目采用仿真、试验和理论相结合的手段，对TBM滚刀作用下刀岩接触力测试方法及分布特性、密实核动态衍生及裂纹扩展机制、密实核-刀圈摩擦磨损机理、高效辅助破岩技术展开了深入研究，其主要成果包括：1）针对不同地质工况条件，提出了刀岩接触力测试方法，获得了刀岩接触力实测分布曲线，获知了密实核在刀圈周向上的动态衍生效应是导致刀岩接触力呈非连续集中分布的关键原因；2）提出了密实核宏观形态特征的表征方法及其特征参数，并基于腔体膨胀理论和弹塑性理论，推导出考虑所述界面非线性和材料非线性的滚刀-密实核相互作用模型，探究了密实核形态及应力载荷理论变化规律；3）设计了一套密实核动态衍生与裂纹扩展观测方案，包括观测装置设计方案、岩石试样夹持方案、裂纹/密实核自适应聚类检测方法等，为后续定量分析密实核动态衍生过程提供了基础；4）考虑到密实核聚集-流转-溃散动态衍生过程中对刀圈刃部的强烈研磨刻划效应，开展了具有较高相似度的刀岩对磨试验台方案设计、方案论证、装置制备、相似性验证、工程对比、方案优化改进等工作；5）为了降低“三高”（高原岩围压、高岩石强度、高石英含量）等特殊地层下密实核衍生效应剧烈所带来的不良影响，基于激光技术具备功率密度高、非接触式能量传输、可形成热裂纹等独特优势，开展了激光辅助滚刀高效破岩机理研究，提出了两步式激光辅助滚刀破岩仿真建模方法，研究了激光辅助缩尺比例滚刀侵岩/滚压破岩过程，系统分析了孔孔距与刀孔距等关键参数对岩石宏观损伤形貌、岩石破碎块度、侵岩垂直力、侵入难度系数及破碎比能耗的影响规律，证实了激光理论上可辅助滚刀实现高效破岩。本项目研究成果，可为设计制造长寿命滚刀提供理论依据。