越海泥水盾构提前到达施工关键技术研究

由于竖井施工进度滞后,为解决盾构提前到达并保证顺利出洞这一技术难题,以台山核电站1#取水隧洞盾构提前到达施工为例,在理论研究的基础上,对盾构到达前的掘进控制措施进行分析,阐述了预留段隧洞爆破参数设计,并对提前到达的关键技术及控制要点进行总结。得出以下结论:1)盾构提前到达盾构井预留5 m的安全距离,并将刀盘后退掌子面0.7 m的方案是可行的,既能加快施工进度,又能有效地保护盾构设备;2)盾构到达预留段前采用"小推力、低转速"的掘进原则,预留5 m段采用"爆破开挖+锚喷支护+管片二次衬砌"相结合的施工方法,保证了盾构安全顺利出洞,有效地控制了管片上浮、错台和接缝处漏水等现象。

Key Construction Technologies for Arrival of Sea-crossing Slurry Shield before Completion of Arriving Shaft Sinking

In the construction of No.1 water conveyance tunnel of Taishan Nuclear Power Station,the shield machine,according to the original plan,was to stop boring at the position 140.6 m away from the arriving shaft,with the remaining tunnel section to be excavated by drill＋blast method from the arriving shaft.However,due to the legging of the shaft sinking,the shield machine has to continue boring to the position 5 m away from the arriving shaft,so as to keep the overall construction schedule of the project.In the paper,the measures taken before shield arriving are analyzed,the design of the blasting parameters for the last 5 m-long tunnel section is described and the key technologies and control points for the arrival of the shield machine are summarized.Conclusions drawn are as follows：1） The solution that the shield machine stops boring at the position 5 m away from the arriving shaft and then the cutter head of the shield machine is withdrawn 0.7 m away form the tunnel face is feasible,which not only guarantees the construction schedule of the project,but also guarantees the effective protection of the shield machine;2） In the arriving section,the shield machine advances under small thrust force and low rotation speed;the remaining 5 m-long tunnel section is excavated by drill＋blast method and supported by rock bolting,shotcreting and secondary segment lining.In this way,the successful arrival of the shield machine is guaranteed and the uplifting and dislocation of the segments and the water seepage from the segment joints are brought under effective control.