软弱围岩隧道进洞施工支护参数优化设计研究

Research on optimal design of support parameters for tunnel entry construction in weak surrounding rock

软弱围岩高陡边坡隧道进洞开挖时,采用玻璃纤维锚杆超前支护,在提高边坡稳定性、控制洞内收敛及优化衬砌受力等方面,都有一定的优越性。文章依托采用该工法的在建隧道工程,利用有限元分析软件MIDAS-GTS建立三维数值模型,考虑软弱围岩变形控制技术,对隧道掌子面不同支护工况下的软弱围岩隧道进洞过程进行数值模拟。研究结果表明,隧道掌子面挤出变形、地表沉降、拱顶下沉及水平收敛均随玻璃纤维锚杆间距的减小而降低,为了提升隧道掌子面稳定性可以选择适当提升玻璃纤维锚杆的密度。基于锚杆轴力分析,提出了支护的最优设计方案。

During the tunnel excavation of high and steep slopes with weak surrounding rock,the use of glass fiber bolts for advanced support has certain advantages in improving the stability of the slope,controlling the convergence in the tunnel and optimizing the stress of the lining.In this paper,relying on the tunnel project under construction using this method,the finite element analysis software MIDAS-GTS is used to establish a three-dimensional numerical model,and considering the deformation control technology of the weak surrounding rock,the tunnel entry for the weak surrounding rock under different supporting conditions of the tunnel face is carried out.The process is numerically simulated.The research results show that:The extrusion deformation of the tunnel face,surface settlement,vault subsidence and horizontal convergence all decrease with the decrease of the distance between the glass fiber bolts.In order to improve the stability of the tunnel face,an appropriate increase can be selected.The density of the glass fiber bolt.Based on the analysis of the axial force of the bolt,the optimal design scheme of the support is proposed.