白城隧道工程大断面马蹄形盾构始发与接收技术

为解决大断面马蹄形盾构始发与接收难点,以蒙华铁路白城隧道工程为依托,对大断面马蹄形盾构始发和接收施工关键技术进行总结。其关键技术包括： 1) 始发阶段采用加强明洞代替传统盾构反力架,可降低反力架的制作、拆除费用和减少始发负环管片用量,有效缩短主体施工时间,节约项目成本; 2）始发基座的底部均匀铺设豆砾石,可减少盾构进入原状土后始发导洞与管片背部间隙回填时间; 3）始发阶段创新地采用套拱钢架代替传统始发端墙结构,减少始发附属设施的工程量,缩短始发准备时间; 4）接收阶段基座与端墙相结合,降低盾构在软弱地层接收安全风险; 5）优化盾构始发和接收位置,使盾构施工和明洞主体作业面充分利用、互不干扰,实现较好的经济效益和安全效益。

Launching and Receiving Technology of Large Cross sectionHorseshoe shapedShield Used in Baicheng Tunnel

The shield launching and receiving is one ofdifficulties for large cross section horseshoe shaped shield tunnel construction. In this paper, the keyconstruction technologies of shield launching and receiving of large cross section horseshoe shaped shield used inBaicheng Tunnel on Menghua Railway are studied and summarized. The keytechnologies adopted include: (1) In the shield launching stage, the cost ofreaction frame production and dismantling and the amount of original negativering pipe can be reduced by replacing traditional shield reaction frames bystrengthened open hole, which helps to shorten the construction time and savethe cost. (2) The bottom of launching base is evenly laid with bean gravel toreduce the backfilling time of hollow between launching guide hole and pipeafter the shield enters undisturbed soil. (3) In shield launching stage, thearch steel frame is innovatively adopted to replace the traditional launchingendwall structure, which reduces the construction amount of launching ancillaryfacilities and shortens launching preparation time. (4) In receiving stage, thebase is combined with the endwall to reduce the security risk of the shieldmachine receiving in the weak stratum. (5) The launching and receivingpositions of shield are optimized to make full use of the main operationsurface of shield tunneling and open tunnel without interfering with eachother, which would realize better economic and safety benefits.