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软岩大断面隧道施工中掌子面的挤出位移及其前方的先行位移对开挖稳定性影响很大,因此以某软弱围岩铁路隧道大断面施工为例,针对两种预支护加固——掌子面玻璃纤维锚杆预加固和管棚超前支护,设定了5种计算工况,分别进行了开挖过程中掌子面前方的先行位移、掌子面挤出位移和掌子面后方最终位移变化的三维数值模拟,并考察了相应塑性区的分布情况,结果表明:管棚超前支护对最终位移和先行位移有明显的控制作用,掌子面超前玻纤锚杆加固对先行位移有一定的控制作用,但对最终位移的控制作用不明显;与管棚超前支护相比,掌子面锚杆加固对掌子面的挤出变形的控制作用更明显;超前管棚支护更能抑制拱部上方围岩塑性区的发育,而掌子面锚杆加固对抑制超前核心土塑性区发育的效果更好。
In the soft rock large section tunnel construction, the extrusion displacements of the face and its front displacement have a great influence on the excavation stability. Taking the large section construction of a weak surrounding rock railway tunnel as an example, - Pre-reinforcement of fiberglass anchor rod and advance support of pipe roof, five kinds of calculation conditions were set up, the first displacement in front of the face of the excavator and the displacement Face three-dimensional numerical simulation of the final displacement changes, and investigated the distribution of the corresponding plastic zone, the results show that: the pipe shed ahead of the final displacements and displacement displacement of the obvious control, The first displacement has a certain control effect, but the control effect on the final displacement is not obvious. Compared with the advanced support of pipe roof, the control effect of the reinforcement of the anchor face on the extrusion deformation of the face is more obvious. The support can restrain the development of the plastic zone of the surrounding rock above the arch, while the reinforcement of the palm face anchor rod can better inhibit the development of the advanced plastic zone of the core.