双向八车道连拱隧道施工方案优化分析

 利用有限元计算法对双向八车道连拱隧道IV，V级围岩的2种施工方法(双侧壁导坑和CRD法)进行模拟。计算和比较这2种施工方法下围岩应力和位移控制效果，结果表明，双侧壁导坑法可以更好地发挥围岩自身承载能力和初期衬砌支护作用，有利于提高二次衬砌的安全储备；CRD法对隧道两侧边墙水平位移控制比较有利，但对隧道顶部围岩沉降控制不如双侧壁导坑法有效。从总体上分析结果可知，双侧壁导坑法更适合于双向八车道连拱隧道施工。

OPTIMUM ANALYSIS OF CONSTRUCTION SCHEME OF MULTI-ARCH TUNNEL WITH EIGHT TRAFFIC LANES

By finite element method，the courses of dynamic construction of multiple-arch tunnels with eight traffic lanes and surrounding rocks of class IV and V are simulated；the excavation effects of two construction methods，which are the double-side-drift method and the CRD method，are compared based on the displacements of surrounding rock mass and preliminary lining and the second lining. Through comparing the numerical calculation results of stresses and displacements in surrounding rock，it can be concluded that the double-side-drift method has advantages in coupling the surrounding rock and the preliminary lining into full play of supporting the tunnel，which will benefit the second lining with certain safety margin. The CRD method is of advantages in horizontal displacement control，but it is not as effective as the double-side-drift method in vertical displacement control at the tunnel top according to the numerical calculation of multiple-arch tunnel with eight traffic lanes. It can be concluded that from overall analysis，the double-side-drift method is more suitable than the CRD method in multiple-arch tunnel with eight traffic lanes.