明暗挖结合地铁车站暗挖隧道断面优化研究——以南宁地铁3号线青秀山站为例

Cross-section Optimization of Mining Tunnel of Metro Station by Cut-and-Cover and Mining Method:a Case Study on Qingxiushan Station on Nanning Metro Line No.3

明暗挖结合地铁车站暗挖隧道部分随着断面尺寸的增大,结构风险成数量级增加。为达到在功能合理前提下,尽量减小暗挖断面尺寸以降低结构风险的目的,通过将暗挖隧道结构高风险性纳入设计评价体系,提出建筑设计标准回归规范要求、梳理机电设计标准盲点、调整机电系统方案、优化建筑形体的建筑设计优化理念。经与实际工程结合,总结出3项具体措施:1)简化暗挖隧道部分功能,将功能精简或转移至明挖空间;2)重整暗挖隧道群体内功能之间几何关系,有效规划,减小尺度;3)尊重暗挖隧道圆形、马蹄形断面有利受力特征,规整断面功能形体尽量与隧道无缝贴合。所述优化措施经南宁地铁3号线青秀山站运用实践,可有效减少暗挖隧道数量,减小暗挖隧道断面,扩大暗挖隧道间距,综合优化断面面积约30%,较好地降低了暗挖结构风险。

With the increase of cross-section size of mining tunnel in metro station by cut-and-cover and mining method,the structural risk multiplies.In order to reduce the mining cross-section size as far as possible under the premise of reasonable function and further reduce the structural risk,the architectural design optimization concept of returning to the standard requirements of architectural design standards,combing out the blind spots of electromechanical design standards,and promoting the adjustment of mechanical and electrical design schemes is proposed by incorporating the high risk of mining tunnel structure into the design evaluation system.According to project practice,three specific measures are summarized as follows:(1)Simplifying the partial functions of the mining tunnel,and simplifying or transferring the functions to the open excavation space.(2)Reorganizing the geometric relationship between the functions in the mining tunnel group,and effectively planning and reducing the scale.(3)Paying attention to the favorable stress characteristics of the circular and horseshoe-shaped cross-section of the tunnel,and making the functional shape of the regular cross-section seamless with the tunnel.The measures mentioned above are applied to Qingxiushan Station in Nanning Metro Line No.3,which can effectively reduce the number and the cross-section size of tunnels,and expand the distance between tunnels.The comprehensive optimization cross-section area reaches about 30%,which can reduce the risk of mining structure.