高速铁路单线隧道Ⅳ级围岩台阶法施工参数选择

Parameter Selection for Construction of HSR Single-track Tunnel Class Ⅳ Surrounding Rock by Benching Tunnelling Method

为研究隧道台阶法施工时不同台阶高度及长度对隧道变形的影响,以西十高铁秦岭马白山单线隧道为工程依托,采用三维有限元计算模型,对不同台阶高度和长度下围岩变形及初支结构稳定性的变化规律进行研究。结果表明:台阶高度对掌子面变形、塑性区分布、拱顶沉降及初支收敛有较大影响;不同台阶长度的掌子面纵向变形较小,随台阶长度增大,拱顶最大沉降量及初支收敛变形量逐渐增大,当台阶长度达到20 m后两者基本趋于稳定;Ⅳ级围岩地段,单线隧道台阶高度宜为6.5~8.0 m,综合考虑隧道施工机械设备排布情况,台阶长度取20~40 m较合适。隧道施工过程中,拱顶沉降、初支收敛等监测结果均满足施工安全要求,验证了研究结果的可行性,并可为相关工程台阶法施工提供参考。

Based on Qinling Mabaishan Single-track Tunnel of Xi'an-Shiyan HSR,this paper uses a threedimensional finite element calculation model to study the change law of surrounding rock deformation and primary support structure stability under different bench heights and lengths during construction by benching tunnelling method.The results show that:a)the bench height has a great impact on tunnel face deformation,plastic zone distribution,arch crown settlement and primary support convergence;b)the longitudinal deformation of the tunnel face with different bench lengths is small.With the increase of bench length,the maximum arch crown settlement and primary support convergence deformation gradually increase.When the bench length reaches 20 m,both tend to be stable;c)for ClassⅣsurrounding rock sections,the bench height of single-track tunnel should be 6.5~8.0 m.Considering the arrangement of tunnel construction machinery and equipment,it is appropriate to take the bench length as 20~40 m.During tunnel construction,the monitoring results of arch crown settlement and primary support convergence meet the construction safety requirements,which verifies the feasibility of the study results and can provide reference for the construction of related projects by benching tunnelling method.