深埋隧道两级螺旋式刀盘掘进地应力释放机理研究

【目的】护盾式全断面岩石隧道掘进机(TBM)掘进大埋深山岭隧道时,平面式刀盘存在直接掘进的岩爆风险高等问题,亟需对地应力释放机理进行研究,设计一种使地应力稳定释放的刀盘方案。【方法】课题组聚焦一种地应力逐级释放的两级螺旋式刀盘方案,进行两级刀盘开挖围岩过程的大型三维有限元数值模拟,研究盘面间距和一级刀盘直径对围岩变形和应力释放的影响规律。【结果】1)当盘面间距为30 m时,即一级掘进完成后再进行二级掘进,可以避免两级刀盘同时掘进过程中所引起的地应力交汇现象。2)一级刀盘直径为2 m时,两级螺旋式刀盘在隧道掘进中两刀盘释放的应力值都约为平面式刀盘的50%。3)盘面间距统一为3 m时,在隧道末端,一级刀盘直径为2 m时隧道变形量在X方向仅为0.7 mm,Y方向为2.7 mm;一级刀盘直径为5 m时隧道变形量在X方向为0.9 mm,Y方向为4.7 mm。【结论】1)螺旋式两级刀盘的盘面间距对隧道形变的位移量影响不明显,一级刀盘直径对隧道形变的位移量影响明显。2)两级刀盘二级掘进可显著改善地应力的释放状况,降低单次释放的地应力值,提高隧道稳定性,降低岩爆发生的可能性。

Simultaneous effects of joint spacing and joint orientation on the penetration rate of a single disc cutter

This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine （TBM） disc cutter as modeled by the Discrete Element Method （DEM）. The input data for the siLmulations were obtained from the sandstone along the AIborz tunnel that is currently being excavated in Iran using a 5.2 m diameter open TBM. Three joint spacings, 150, 200, and 300 mm, were modeled together with seven values of joint orientation; 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that the penetration increases when joint orientation increases from 0° to 75°, but it decreases as the joint orientation increases further from 75° to 90°. This is true for each joint spacing. In addition, for a given joint orientation increasing the joint spacing causes the TBM penetration to decrease. The optimum joint orientation, from the viewpoint of TBM penetration, is about 60-75°.