With the increasing number of long tunnelling and urban subway constructions, mixed-face ground conditions are frequently encountered. Rock fragmentation mechanism under disc cutter cutting in TBM tunneling through the mixed-face ground is complex and can lead to engineering difficulties. During TBM tunneling in mixed-face ground with soft rock in upper layer and hard rock in the lower layer, reduction of the advance rate and reduced rotational speed of cutter head occur compared with homogeneous ground. As a result, the muck in the working chamber cannot be replaced timely, leading to the formation of mud cake. Additionally, the disc cutters cannot rotate normally and are worn eccentrically and severely. Finally, the cutters collide with hard rock periodically at the interface between soft and hard rock, thus being subject to a huge impact load, even overload on some cutters, resulting in chipping of the cutter ring and damage to the cutter holder. This paper presents numerical analysis of the disc cutter cutting process considering the difference of rock-cutting behaviors of disc cutters in the mixed-face ground with the aid of PFC3D code. Based on the forces imposed on the disc cutter and rock crack propagation, TBM tunneling in the mixed-face ground is investigated. The decrease of the mean rolling force of the disc cutter causes rotation hindering in the disc cutter in soft rock stratum leading to flat cutter wear. The gap of the normal force between the soft rock and hard rock generates the overturning moment of the cutter head, which causes the eccentricity and vibration of the cutter head.

中文翻译：

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基于三维粒子流模型的混合地层圆盘刀具切岩过程研究

随着长隧道和城市地铁建设数量的增加，经常遇到混合面地层条件。TBM隧道通过混合面地层的圆盘刀具切割下的岩石破碎机制复杂，会导致工程困难。TBM在上层软岩下层硬岩的混合面地层掘进时，与均质地层相比，存在推进速度和刀盘转速降低的现象。造成工作腔内的淤泥不能及时更换，形成泥饼。另外，盘形刀具不能正常旋转，偏心磨损严重。最后，刀具在软硬岩界面处周期性地与硬岩碰撞，从而承受巨大的冲击载荷，甚至某些刀具过载，导致刀具环碎裂和刀架损坏。本文借助PFC3D代码，对考虑混合工作面地层中盘式刀具切削性能差异的盘式刀具切削过程进行了数值分析。基于作用在盘形刀具上的力和岩石裂纹扩展，研究了在混合面地层中的TBM隧道掘进。在软岩地层中，盘形刀具平均轧制力的降低导致盘形刀具旋转受阻，导致平刀具磨损。软岩和硬岩之间法向力的间隙产生刀盘的倾覆力矩，从而引起刀盘的偏心和振动。导致刀环碎裂和刀架损坏。本文借助PFC3D代码，对考虑混合工作面地层中盘式刀具切削性能差异的盘式刀具切削过程进行了数值分析。基于作用在盘形刀具上的力和岩石裂纹扩展，研究了在混合面地层中的TBM隧道掘进。在软岩地层中，盘形刀具平均轧制力的降低导致盘形刀具旋转受阻，导致平刀具磨损。软岩和硬岩之间法向力的间隙产生刀盘的倾覆力矩，从而引起刀盘的偏心和振动。导致刀环碎裂和刀架损坏。本文借助PFC3D代码，对考虑混合工作面地层中盘式刀具切削性能差异的盘式刀具切削过程进行了数值分析。基于作用在盘刀上的力和岩石裂纹扩展，研究了在混合面地层中TBM掘进。在软岩地层中，盘形刀具平均轧制力的降低导致盘形刀具旋转受阻，导致平刀具磨损。软岩和硬岩之间法向力的间隙产生刀盘的倾覆力矩，从而引起刀盘的偏心和振动。本文借助PFC3D代码，对考虑混合工作面地层中盘式刀具切削性能差异的盘式刀具切削过程进行了数值分析。基于作用在盘形刀具上的力和岩石裂纹扩展，研究了在混合面地层中的TBM隧道掘进。在软岩地层中，盘形刀具平均轧制力的降低导致盘形刀具旋转受阻，导致平刀具磨损。软岩和硬岩之间法向力的间隙产生刀盘的倾覆力矩，从而引起刀盘的偏心和振动。本文借助PFC3D代码，对考虑混合工作面地层中盘式刀具切削性能差异的盘式刀具切削过程进行了数值分析。基于作用在盘形刀具上的力和岩石裂纹扩展，研究了在混合面地层中的TBM隧道掘进。在软岩地层中，盘形刀具平均轧制力的降低导致盘形刀具旋转受阻，导致平刀具磨损。软岩和硬岩之间法向力的间隙产生刀盘的倾覆力矩，从而引起刀盘的偏心和振动。研究了混合工作面地层中的 TBM 隧道掘进。在软岩地层中，盘形刀具平均轧制力的降低导致盘形刀具旋转受阻，导致平刀具磨损。软岩和硬岩之间法向力的间隙产生刀盘的倾覆力矩，从而引起刀盘的偏心和振动。研究了混合工作面地层中的 TBM 隧道掘进。在软岩地层中，盘形刀具平均轧制力的降低导致盘形刀具旋转受阻，导致平刀具磨损。软岩和硬岩之间法向力的间隙产生刀盘的倾覆力矩，从而引起刀盘的偏心和振动。