中文摘要：

拱北隧道口岸暗挖段管幕工程初步设计阶段推荐采用两种直径钢管的组合管幕。在施工设计阶段,结合施工单位的施工水平、现场试验管研究成果及施工经验,对管幕设计进行了优化,统一了管幕钢管直径,调整了断面布置形式,优化了管幕顶进和接收等施工组织方案。考虑流固耦合作用,文章利用有限差分方法对两种方案进行了数值模拟,分析结果表明：统一管幕钢管直径的方案在衬砌变形、内力和地表沉降等方面均优于原方案;开挖引起的孔隙水压力降低会产生土体的固结沉降,冻结区解冻后沉降更加显著。通过综合考虑,统一管幕钢管直径的方案可在不降低管幕稳定性和结构安全度的基础上,降低工程投资,减少设备投入,施工技术方面更加可行,有效降低了施工风险。

英文摘要：

A pipe-roof combining two kinds of steel pipes with different diameters was recommended in the preliminary design phase for the bored section of the Gongbei tunnel. During the construction design phase, and combining the construction level of the construction unit and the research results of a field pipe test, both the design option and the construction scheme of the pipe-roof were optimized in terms of a unified pipe diameter,section pattern type, launching and receiving of the jacking pipe. Considering the fluid-solid coupling interaction,these two schemes were simulated using the finite difference method. The results show that the unified pipe diameter scheme is superior to the original one in terms of lining deformation, internal force and surface subsidence, and the excavation-induced pore-water pressure drop will generate a consolidation settlement of soil,which is more significant in thawed frozen areas. Through synthetic consideration, the unified pipe diameter scheme can reduce engineering and equipment investments without decreasing the stability and structural safety of the pipe-roof, and it is most feasible in low-risk construction techniques.