深部高地应力地层TBM破岩机理及掘进性能预测研究

In deep grounds, high in-situ stress can usually induce engineering problems such as rock slabbing and burst, and then seriously threatens the excavation efficiency and safety of the tunnel boring machine. Focused on the key scientific problem “Rock cutting mechanism and excavation performance prediction for tunnel boring machine in deep grounds under high in-situ stress”, experimental, numerical and field methods are all employed. First, the microscopic rock damaging/cracking mechanism, rock failure/response zones and dynamic crack initiation/propagation process during the rock indentation process are revealed. Second, the changing rule of rock intactness degree, disc cutter cutting forces and rock cutting efficiency with increasing confining stress during the rock disc cutting process are studied. Then, the relations among laboratory rock cutting test results, theoretical/empirical TBM preformation prediction models and field TBM excavation performance data are established. Finally, the influence of high in-situ stress on the thrust per cutter, net penetration rate and rock boreability index are analyzed, the prediction method for rock boreability index in highly-stressed fractured rock mass is proposed, the occurrence mechanism, precaution method and supporting principles for rock slabbing and burst under high in-situ stress are proposed. The results of this study can improve the TBM cutter/cutterhead design, excavation state evaluation, operation parameter selection and supporting method optimization, leading to the effective and safe TBM excavation in deep grounds under high in-situ stress.

高地应力通常会诱发深部岩层出现岩石板裂和岩爆灾害等工程问题，严重威胁TBM的施工效率和安全。本项目拟围绕“深部高地应力地层TBM破岩机理及掘进性能预测方法”这一关键科学问题，借助室内试验、数值模拟和现场研究，揭示不同围压下滚刀破岩时岩石微观损伤破裂机制、破坏响应分区及裂纹网络萌生扩展全过程，揭示岩石完整性、滚刀三向受力和岩石破碎效率在围压增加时的变化规律，建立室内岩石切削试验结果、理论和经验TBM性能模型预测结果与现场TBM掘进性能实测结果之间的相关关系模型，揭示深部高地应力对TBM掘进过程中单刀推力、净掘进速度和岩体可掘性指数的影响规律，提出深部高地应力地层节理岩体可掘性指数多指标预测方法，揭示高地应力下岩石板裂和岩爆灾害的发生机理、预警方法和支护原则。本项目的研究成果有助于指导TBM刀盘刀具布置、运行状态评价、掘进参数选择和支护措施优化，进而实现深部高地应力地层TBM安全高效掘进。

TBM掘进施工时，深部高地应力很有可能会降低其掘进速度和支护进度，诱发岩石板裂和岩爆灾害，严重威胁TBM施工效率和施工安全。所以，开展深部高地应力地层TBM破岩机理研究、掘进性能预测和安全支护技术研究已经成为实现交通、水利和矿山重大工程建设中TBM安全高效掘进迫切需要解决的关键难题。因此，本项目围绕“深部高地应力地层TBM破岩机理及掘进性能预测方法”这一关键科学问题，进行了如下研究工作：（1）通过室内滚刀贯入破岩物理试验和数值模拟揭示了不同围压下岩石内部微观损伤破裂机制、破坏响应分区划分及裂纹网络萌生扩展动态全过程；（2）通过室内滚刀线性切削破岩物理试验和数值模拟揭示了岩石完整性、滚刀三向受力和岩石破碎效率在双向围压增加时的变化规律；（3）通过与现场TBM掘进性能实测数据的对比建立了室内岩石切削试验结果、理论和经验TBM性能模型的预测结果与现场TBM掘进性能实测结果之间的相关关系模型；（4）通过分析现场三维地应力分布特征和现场TBM掘进性能实测数据揭示了深部高地应力对TBM单刀推力、净掘进速度和岩体可掘性指数的影响规律，揭示并提出了深部高地应力下岩石板裂和岩爆灾害的孕育发生机理、预测预警方法和安全支护原则。本项目最重要的研究成果为：揭示了深部高地应力条件下TBM破岩机理和掘进性能的变化规律，即（1）随着围压增加，围压对滚刀切削下的岩体存在三个影响阶段：强化阶段、损伤阶段和破碎阶段；（2）随着围压增加，低围压抑制滚刀破岩逐渐转化为高围压促进滚刀破岩。上述研究成果有助于指导深部高地应力地层TBM刀盘刀具布置、运行状态评价、掘进参数选择和支护措施优化，进而实现深部高地应力地层TBM安全高效掘进。