多心圆拱隧道支护结构内力反演分析的理论研究

Back Analysis of the Internal Force on the Supporting Structure of a Multi-Centered Circular Arch Tunnel

在施工环境下对多心圆拱隧道支护结构的内力分布特征进行研究,是保证隧道施工安全的关键措施之一。文章采用弹性地基曲梁理论,基于初参数法和现场围岩量测压力,从理论上推导了多心圆拱隧道支护结构内力计算的反演表达式,并结合集呼高速旗下营隧道某断面围岩压力的实测数据,反演了隧道衬砌结构的内力分布情况,对衬砌结构的薄弱部位进行了安全性评价。结果表明,隧道BG弧段衬砌结构弯矩和剪力较大,在施工过程中应加强该部位的现场监测工作;隧道拱顶部位混凝土可能出现弯拉造成的开裂现象,应注意加强观测。

It is important to understand the characteristics of the internal force distribution of the supporting structure of a tunnel with multi-centered circular arch in complicated construction conditions to ensure safe tunnel construction. Based on the initial parameter method and site-measured pressures of the surrounding rock, an inversion expression for the internal force calculation of the supporting structure of the multi-centered circular arch tunnel is theoretically derived using the theory of a curved beam on an elastic foundation. Based on the measured pressures of the surrounding rock of a certain section of the Qixiaying tunnel, a back analysis is conducted for the internal force distribution of the tunnel lining structure and a safety evaluation of the weak parts of the tunnel structure is undertaken. The results show that site monitoring should be strengthened for the weak parts during construction since the bending moment and shearing force of the lining structure at the BG arc section are relatively large; monitoring and observation should also be improved since concrete cracking could occur at the tunnel crown due to bending.