浅埋偏压小净距隧道进洞施工方案优化研究

Optimization of construction scheme of small spacing tunnel with shallow-buried bias

以莆炎高速公路布盂隧道工程为依托,对浅埋偏压小净距隧道进行施工方案优化。采用MIDAS GTS NX软件建立浅埋偏压小净距隧道三维有限元模型,分析了双侧壁导坑法、中隔壁法、三台阶法3种施工方案下的围岩应力和变形特征、围岩塑性区分布、中间岩柱水平位移,并将数值计算值与现场监测值进行对比分析。研究结果表明:中隔壁法在保证施工安全、降低施工成本、缩短工期方面能起到良好的作用,综合考虑本项目工程地质条件与工法特点,洞口小净距段最终采用中隔壁法进行施工,现场实践表明该方法切实可行。

Based on the Buyu Tunnel Project of Puyan highway,the optimization of the construction scheme of small spacing tunnel with shallow-buried bias is studied.The three-dimensional finite element model of small spacing tunnel with shallow-buried bias is established by Midas GTS NX software.Furthermore,the stress and deformation characteristics of surrounding rock,distribution of plastic zone,horizontal displacement of intermediate rock pillar under three construction schemes of both side drift method,center diagram method and three-steps method are analyzed,and the theoretical calculation value and field monitoring value are compared and analyzed.The results show that the middle wall method can ensure the construction safety,reduce the construction cost and shorten the construction period.Considering the engineering geological conditions and the characteristics of construction method of the project,the middle wall method is adopted for the construction of the small spacing section of the portal,and field practice shows that the method is feasible.