超前导洞不同扩建方案对隧道稳定性的影响研究

Research on the Influence of Different Expansion Schemes for Pilot Heading on Tunnel Stability

利用圆形超前导洞经扩建形成隧道断面,运用FLAC有限差分软件进行建模分析,研究超前导洞经不同方案扩建成隧道后的围岩稳定性是否存在着差异,对水平位移、竖向位移及塑性区三方面内容进行研究,结果表明:两台阶扩建方案优于全断面扩建;超前导洞扩建成隧道施工过程中,拱脚围岩存在局部失稳风险;台阶法扩建更加有利于支护结构受力。

The circular pilot heading is expanded to form a tunnel section, and the modeling analysis is carried out by utilizing FLACfinite difference software to study whether there are differences in the stability of surrounding rock after the pilot heading is expanded into a tunnel through different schemes. Three aspects like horizontal displacement, vertical displacement and plastic zone are explored. The results show that: the two-step expansion scheme is better than the full section expansion scheme;during the construction of expanding the pilot heading into a tunnel, there is a local instability risk in the surrounding rock of the arch foot;the expansion with bench method is more conducive to the stress of the supporting structure.