地铁区间矿山法大断面隧道内轮廓参数确定方法

地铁区间线路往往设有联络线、停车线等线路。这些区间的线路变化复杂处的隧道可能出现矿山法大断面结构形式。从限界要求出发,介绍了确定矿山法隧道内轮廓的要点,采用勾股定理法确定内轮廓上部圆弧,并针对几种不同的内轮廓进行解析,计算分析其优劣,得到以下结论:仰拱半径越小,整体结构受力越有利,但开挖及回填面积都将增大,结构经济性指标降低;建议矿山法大断面隧道内净高与净跨之比约为0.7~0.75,仰拱半径与隧道净高之比约为1.35~1.45。

Method of Determing the Inner Outline of Metro Tunnels Built with Mining Method

There are often connecting lines and stabling lines lie in metro sections.Structure with large cross-section tunnel built with mining method may be applied to places of complex line arrangement.In this paper,the main points of determining inner outline of tunnels built with mining method are introduced based on gauge limitation requirements.The upper arch of tunnel inner outline can be conveniently determined by Pythagorean Theorem,several kinds of inner outlines are inducted through comparison.The results are as follows:the smaller invert radius,the better structural forces will be.In such condition,the excavation and backfill area will be increased,but the economic index reduced.Suggestions are given that the ratio of tunnel inner clear height to innerclear span shall be controlled in 0.7～0.75,and the ratio of invert radius to tunnel clear height in 1.35～ 1.45 for large cross-section tunnel.