双洞八车道公路隧道施工方案研究

双洞八车道公路隧道最大跨度在23m左右，扁平率小于0．5，为超大断面隧道。通过对某双洞八车道公路隧道在几种围岩条件下多种施工开挖方案的有限元计算分析，得出双洞八车道公路隧道宜采用三心圆拱型断面和复合式支护衬砌，软弱围岩段宜采用双侧壁导坑法开挖，并通过相似模型实验研究，得到隧道围岩在施工中的位移发展，遵循台阶式发展过程并符合Hill函数变化规律，可对类似工程设计施工提供类比和指导。

A Study on Construction Schemes of Highway Twin Tunnel with Eight Travelled lanes

The caving width of highway twin tunnel with eight travelled lanes is over 23 meters and its oblateness is small than 0.5. Through FEM analysis of the constructure of this tunnel engineering under different surrounding rock mass conditions, the cross section of the tunnel should be three-centered arch and its structure is constant section composite lining. And the constructure of the soft rock mass tunnel should be caved with drift method on both sides. Also through long-span physical simulation experiment, the periphery displacement development of this tunnel is flight of steps, and approximates to Hill function. That may guide the design and construction for similar projects.