隧道进出口线形协调性研究

分析平曲线、竖曲线、平纵曲线组合及横断面对隧道安全的影响，对隧道进出口线形协调性进行研究，并提出：隧道进出口应尽量设在直线段上或圆曲线段上，避免设在缓和曲线上；对于洞口处的纵坡，除应采用较大的竖曲线半径外，隧道洞口的变坡点应距洞门有一定的距离；隧道洞口段的平纵面线形组合须避免在进、出洞口的洞外段、洞内段设置较长、较大的下坡，且在洞口处均需设置小半径的平曲线进、出洞；隧道洞内外的路面宽度应逐渐过渡，且长大隧道内应设置紧急停车带。

Research on Curve Coordination of Tunnel Inlets and Outlets

This paper analyzes influences of horizontal curve, verncat cu ,~ vertical curves and cross section on tunnel safety, studies the curve coordination of tunnel inlets and outlets, and proposes that tunnel inlets and outlets should be set on straight-line segments or circular curve segments as much as possible and avoid setting on transition curve; for longitudinal slopes at the portal, besides adoption of large vertical curve radius, the point of change slope of the tunnel portal should be at a certain distance from the portal; linear combination of horizontal and vertical surfaces at tunnel portal segment should not set long and large down slopes at outside and inside segments of the portal into and out of the portal, and horizontal curves at small radius at the portal to come in and out of the portal; the road width inside and outside the portal should transit gradually and emergency parking strips should be set in long and large tunnels.