TBM多级刀盘自由面破岩机理和动态载荷行为研究

Full-face tunnel boring machines (TBMs) are key equipment for rock tunnel excavation, which are especially applied to high-speed railway and expressway tunnel projects as well as huge water diversion works. Aiming at the difficulties frequently occur when TBMs bore in hard rock grounds and based on the invention patent of multi-stage cutterhead authorized to the applicant’s team and its high efficiency rock breaking method, this project is to study the rock breaking mechanism of free face structure and dynamic load behaviors of the multi-stage cutterhead and cutters so as to improve the rock breaking efficiency and penetration rate of TBMs. The particle discrete element method (DEM) based numerical model of rock breaking for free face structure is developed and validated with rock breaking tests. The influences of rock types, free face structures and cutter penetrating arrangements on the rock crack initiation and propagation are studied so as to reveal the rock breaking mechanism of free face structure. The explicit numerical model of the rock mass excavation process with the multi-stage cutterhead is developed and validated with rock excavation tests. The influences of the cutterhead structure and boring parameters, intact rock mechanical properties and rock mass structures on the cutterhead’s thrust, torque as well as cutters’ rock breaking forces are studied, to reveal the evaluation mechanism of free faces. Based on the simulations and experiments on the rock excavation process, the dynamic boring efficiency of the multi-stage cutterhead is evaluated considering the penetration rate and specific energy. This project will make breakthroughs in basic scientific problems including the rock breaking mechanism and dynamic load behaviors of the multi-stage cutterhead. This will provide a basis for the design of new type multi-stage cutterheads to improve the rock breaking efficiency and penetration rate of TBMs.

全断面隧道掘进机（TBM）是开掘各类岩石隧道的关键装备，尤其用于高速铁路、公路隧道和大型引水工程。本项目针对TBM在高硬地质下常遇的“掘不动、掘不快”瓶颈问题，依托申请者团队已获授权的多级刀盘发明专利及其高效破岩掘进方法，研究其自由面破岩机理和刀盘刀具动态破岩载荷行为，从而提高TBM破岩效率和掘进速度。构建滚刀自由面破岩离散元模型并开展破岩试验，研究岩石类型、自由面结构和贯入次序对裂纹萌生扩展机制的影响规律，揭示自由面破岩机理；构建多级刀盘掘进岩体的显式动力学模型并开展掘进试验，研究刀盘结构和掘进参数以及岩石/岩体力学参数对刀盘掘进推力扭矩和滚刀动态破岩载荷的影响规律，揭示自由面群演化机理；基于多级刀盘掘进试验和模拟研究，从掘进速度和比能等角度评价多级刀盘动态掘进效能。本研究将突破多级刀盘破岩机理和动态载荷行为等基础问题，为设计“破岩高效、掘进快速”的多级刀盘提供基础理论和技术支撑。

本项目针对全断面隧道掘进机（TBM）在高硬地质下常遇的“掘不动、掘不快”瓶颈问题，研究多级刀盘自由面破岩机理和刀盘刀具动态破岩载荷行为，从而提高TBM破岩效率和掘进速度。开发了基于泰森多边形算法的等效晶质岩石材料构建技术，所建岩石模型的宏观力学参数与实际值的误差均在4%以下；建立了自由面条件下滚刀静压破岩数值模型，开展了自由面条件下静压和回转破岩试验，静压模拟与试验的载荷误差小于10%，验证了数值模型的可靠性；开展数值模拟，研究岩石类型和自由面结构对裂纹萌生扩展机制的影响规律，揭示自由面破岩机理，自由面条件下破岩载荷可减小达30%、破岩效率可提高45%，自由面与贯入方向平行时破岩效率最高，揭示了自由面间距和高度的双临界值及其原理，发现花岗岩自由面间距不得大于140 mm，研究了基于自由面破岩理论的预切槽辅助破岩机理。采用有限元方法和光滑粒子流动力学相耦合的数值方法构建了TBM滚刀群协同破岩数值模型，选用了基于Rankine拉伸截断的摩尔-库伦弹塑性本构模型表征岩石材料，开展了平面和两级TBM刀盘的大型全尺度掘进试验研究，滚刀法向力相对误差为2.2–11.3 %，验证了数值模型的可靠性，研究了刀盘结构和掘进参数以及岩石/岩体力学参数对刀盘掘进推力扭矩和滚刀动态破岩载荷的影响规律，揭示自由面群演化机理。基于刀盘掘进试验和模拟研究，从可掘进性系数、切削系数、推力、扭矩、岩碴级配与形状、比能、比掘进系数等角度评价刀盘动态掘进效能，建立了基于室内TBM刀盘掘进试验的“载荷-贯入度”、“可掘进系数-贯入度”预测模型。本研究突破了多级TBM刀盘破岩机理和动态载荷行为等一系列基础问题，可为设计“破岩高效、掘进快速”的多级刀盘提供基础理论和技术支撑。