中文摘要：

结合福州国际机场高速公路2期工程魁岐2号双洞八车道特大断面小净距隧道工程,建立了离散元数值模拟分析模型,针对节理岩体中特大断面小净距隧道施工方案进行了优化分析。分别研究了双侧壁导坑法、CRD法和CD法3种施工方案下隧道拱顶下沉、中间岩柱水平位移、围岩水平位移和围岩塑性区的变化规律。基于研究成果,并结合魁岐2号特大断面小净距隧道现场实际情况,在该隧道进口Ⅴ级围岩段,将双侧壁导坑法变更为CRD法,顺利完成了施工,此施工方案的变更对降低施工成本、加快施工进度、缩短施工工期均起到了较好的作用。研究结果可为类似条件下特大断面小净距隧道的设计、施工提供借鉴与参考。

英文摘要：

According to the construction conditions of Kuiqi No.2 small-space tunnel with super-large cross-section and eight traffic lanes in the second phase project of Fuzhou International Airport Highway,a discrete element analysis program is established to simulate the construction process.In the program,the double-heading construction method,CRD method and CD method have been simulated.The settlements of vault,horizontal deformations of middle rock pillar,horizontal deformations of surrounding rock and plastic zone of surrounding rock are analyzed and the advantages of the three methods are compared.Considering the characteristics of Kuiqi No.2 Tunnel,the practical construction scheme is optimized.The double-heading method is changed to CRD method at the tunnel entrance.The modification of construction method has great contribution to cut down the cost and to reduce erection time.The results provide some reasonable references to design and construction for similar engineering.