单洞4车道隧道内轮廓关键指标统计分析与启迪

现行公路隧道设计规范对单洞4车道隧道的构造和设计尚无明确规定。基于其内轮廓设计角度,并参考相关研究成果,提出应将扁平率作为其关键指标。同时,结合对已建成类似隧道工程内轮廓扁平率的统计分析结果,指出对于分离式双洞8车道或单洞4车道隧道,其内轮廓设计时,扁平率（不含仰拱）取0.485,扁平率（含仰拱）取0.605,矢跨比取0.406,具有较好的技术经济性,可为4车道公路隧道设计提供借鉴。

Statistical Analysis for Key Indicators of Contour in Single-hole and 4-lane Tunnels and Enlightenment

The existing codes for design of highway tunnels have not had definite provisions for construction and design for single-hole and 4-lane tunnels yet.This paper,based on design angle of internal contour and by reference to relevant research achievements,proposes the flat ratio as a key indicator.Meanwhile in combination with the results of statistical analysis for flat ratio of internal contour of the constructed similar tunnel projects,the paper points out that a flat ratio（excluding inverted arch） of 0.485,a flat ratio（including inverted arch） of 0.605 and a rise span ratio of 0.406 in design of internal contour for separated double-hole and 8-lane or single-hole and 4-lane tunnels show good technical economy and can provide a reference for design of 4-lane highway tunnels.