大跨公路隧道截面仰拱连接形式优化分析

Optimization Analysis in Connection Form of Inverted Arc of Long-span Highway Tunnel Cross Section

为实现隧道截面仰拱连接处最小弯矩应力的目标，应用有限元原理对目前我国采用较多的大跨公路隧道结构截面形式进行内力计算，通过Ansys优化分析边墙与仰拱的连接部位，找到最优的隧道横断面连接形式；同时考虑到现场支模等施工的需要，优化找出与仰拱直线连接时最优直线段高度．发现直线连接相对于曲线连接弯矩最大值约增大20－30％．在满足净空及工程要求条件下，最大弯矩随直线连接段高度增加出现先减小再增大的趋势，最大弯矩随围岩级别增高增大速率较大．

To achieve the target of minimum bending stress in tunnel invert junction, applying finite element theory to internal force calculation in cross section types of many long-span highway tunnel used in our country at present, the connection part of side wall and inverted arch are analyzed through Ansys optimization. We do optimization analysis to maximum bending moment in each cross section and find the optimum connection pattern of the cross section. Considering the need of the form erection, we do optimization analysis of the optimum length of the line which is connected to inverted arch. Found that the maximum bending moment approximately increase 20% in straight line connection with respect to curve connection. To meet the conditions of clearance and engineering requirements, the maximum bending moment appear the trend of decreases with the straight line connecting segment height increases, the maximum bending moment increases with rate increasing of the rock level.