中国四车道及以上超大断面公路隧道修建技术的发展

伴随经济的迅猛发展,对公路交通提出了更高的通行要求,新建、扩建的四车道及以上超大断面公路隧道频频出现,但却几乎没有学者对此方面的研究做出系统的归纳总结,诸多研究在类比引用时忽略工程案例更为细致的类别而存在些许不合理。基于此,通过广泛深入的调研,依据成因和特征将四车道及以上超大断面公路隧道分成3类:常规新建四车道公路隧道、原位扩建四车道公路隧道和分岔四车道及以上公路隧道;在此基础上,归纳总结分析了四车道及以上超大断面公路隧道断面形状、施工工法、施工力学和支护参数等的技术现状以及研究中存在的不足。在断面形状的研究上,实际工程采用的扁平率波动范围较大,并且大于目前理论研究得到的扁平率和国外大部分隧道采用的扁平率,更为合理的扁平率需要深入研究;在施工工法的研究上,有逐渐减少开挖分部,扩大施工空间,增强机械化施工的趋势,与之配套的自动化程度更高的施工机械急需研发;在施工力学的研究上,对围岩的荷载释放和渐进性破坏过程有了更加深入的认识,但是对深埋段围岩压力的计算方法仍没有统一的有说服力的计算理论;在支护参数的研究上,不同的工程呈现较大的差异,需对超大扁平隧道的支护参数进一步研究和优化,为完善相应的指南或规范奠定理论基础。最后对四车道及以上超大断面公路隧道的建造技术进行了展望,指出设计标准化、施工机械化、结构轻型化等是今后重点研究的内容。

Construction Technology of Super-large Section of Highway Tunnels with Four or More Lanes in China

With the rapid development of the economy, higher vehicle requirements are being put forward for highway transportation. Newly built and expanded super-large sections of single-span highway tunnels with four or more lanes frequently appear; however, few scholars have systematic studied these. Many studies often overlook the more detailed categories of engineering cases, and are unreasonable in both analogy and citation. Based on an extensive and in-depth investigations, this study classifies super-large sections of highway tunnels with four or more lane into three categories according to their causes and characteristics:conventional newly built four-lane highway tunnels, in-situ extensions of four-lane highway tunnels, and bifurcated highway tunnels with four or more lanes. On this basis, the study both summarizes and analyses the technical status of the section shape, construction method, construction mechanics, and support parameters of highway section tunnels; shortcomings in this and other research are also investigated. In the study of section shape, it was determined that the flatness rate used in practical projects fluctuates widely, and is larger than the flatness rate obtained by the current theoretical research used in most foreign tunnels. As such, a more reasonable flatness rate needs to be studied in depth. In the study of construction methods, it was found that there is a tendency to gradually reduce excavation sections, expand construction space, and enhance mechanized construction. Construction machinery with higher degrees of automation is therefore in urgent need of research and development. In the study of construction mechanics, despite the fact that the load release and progressive failure process of surrounding rock are more deeply understood, it was determined that there is still no uniform and convincing calculation theory for the pressure calculation of the surrounding rock in deep buried sections. On the research of support parameters, it was noted that there are great differences among different projects; it is necessary to further study and optimize the support parameters of super-large flat tunnels so as to lay a theoretical foundation for perfecting the corresponding guidelines or codes. Finally, the construction technology of four or more lane super-large cross-section highway tunnel was prospected. It was pointed out that the standardization of design, mechanization of construction, and lightening of structures are the key targets for research in the future.