高铁隧道穿越断层破碎带施工方法及稳定性分析

针对新建福州—厦门高速(350 km/h)铁路碧峰寺隧道穿越F7断层破碎带施工潜在的地质灾害,提出隧道采用三台阶临时仰拱、超前帷幕注浆、弱爆破、早封闭、勤量测的联合施工方法穿越断层破碎带,利用有限差分程序建立了三维数值计算模型,研究了施作和未施作超前注浆预加固作用下隧道施工破碎带围岩的稳定性。研究表明:预注浆加固措施作用下,断层破碎带隧道施工围岩最大变形量降低了137.8 mm,达到了设计的预留变形量,拱顶和拱脚附近应力集中明显减弱,改善了围岩的稳定性,提出的施工方法对破碎带围岩扰动小;结合现场施工监测数据,验证了这种断层破碎带联合施工方法的可行性和适用性;最终隧道施工成功穿越了断层破碎带,保障了工期和施工安全,能为类似工程提供借鉴意义。

Construction Method and Stability Analysis of High-speed Railway Tunnel Crossing Fault Fracture Zone

For the potential geological disasters in the construction of the Bifengsi Tunnel crossing the F7 fault fracture zone on the newly-built Fuzhou-Xiamen High-speed Railway with 350 km/h,it is proposed that a joint construction method,i.e.,three-step temporary inverted arch,advanced curtain grouting,weak blasting,early closure,and frequent monitoring,is adopted to pass through the fault fracture zone.A three-dimensional numerical calculation model using finite difference program may be constructed,and the stability of the surrounding rock in the fracture zone of the tunneling with and without pre-grouting is studied.The results show that under the action of pre-grouting reinforcement measures,the maximum deformation of surrounding rock during tunnel construction in the fault fracture zone is reduced by 137.8 mm,which is within the reserved deformation range of the lining design.The stress concentration near the vault and springing is significantly weakened,which improves the stability of the surrounding rock.The proposed construction method exhibits little disturbance on the surrounding rock in the broken zone.Combined with on-site construction monitoring data,the feasibility and applicability of the joint construction method for fault fracture zone is verified.Finally,the tunnel construction smoothly passes through the fault fracture zone,and the construction period and safety have been guaranteed,which can provide reference for similar projects.