为解决超大跨公路隧道在设计施工过程中普遍存在的工法选择、支护参数确定等技术难题，基于广东省深汕西高速改扩建项目双洞8车道超大跨公路隧道建设实例，通过调研、工程类比、模拟计算等方法，进行超大跨公路隧道在施工工法、支护参数、“一洞九线”大型机械化工装配置以及相关优化设计等方面的研究，并通过监控量测对设计方案进行验证。结果表明： 1）现行规范中2、3车道隧道的设计方法仍基本适用于4车道隧道。2）CD法适用于深埋强风化层，且拱顶强风化层厚度不小于1倍洞身开挖宽度；三台阶法适用于深埋中风化层，且拱顶中风化层厚度不小于1倍洞身开挖宽度。3）采用51超前中管棚、掌子面玻璃纤维锚、涨壳式预应力锚杆以及C30早高强喷射混凝土后，在Ⅳ级围岩中进行机械化施工具有较高的可行性。4）在前述超前预加固以及支护优化的前提下，当仰拱与掌子面的距离优化至106 m（CD法）、118 m（三台阶法），二次衬砌与掌子面的距离优化至160 m（CD法）、190 m（三台阶法），机械化施工可达到安全、高效的预期。

To rationally select construction methods and support parameters in the design and construction process of super-large span highway tunnels, a case study is conducted on a double-hole eight-lane super-large span highway tunnel of the Shenzhen-Shantou western expressway extension project in Guangdong province, China. The investigation, engineering analogies, and simulation calculations are employed to examine the construction method, supporting parameters, "one-hole nine-line" large-scale mechanized tooling configuration, and related optimization design of super-large span highway tunnel. Furthermore, the design scheme is validated through monitoring and measuring. The results reveal the following: (1) The design methods for two- and three-lane tunnels in the current specifications are still basically applicable to four-lane tunnels. (2) The centerdiaphragm(CD) method is suitable for deep and strongly-weathered strata with a thickness in the arch no less than 1 times the excavation width of the tunnel; whereas the three-bench method is suitable for deep and moderately-weathered strata with a thickness in the arch no less than 1 times the excavation width of the tunnel. (3) The mechanized construction method can be applied in Grade Ⅳ surrounding rock after implementing advance middle pipe roof, glass fiber anchor, expanded shell prestressed anchor, and C30 early high-strength shotcrete. (4) Under the premise of advance pre-reinforcement and support optimization mentioned above, the mechanized construction method is applicable when the distance between the invert and the tunnel face is optimized to 106 m (CD method) or 118 m (three-bench method), and the distance between the secondary lining and the tunnel face is optimized to 160 m (CD method) or 190 m (threebench method).