软土城区盾构法地下道路分合流处非开挖技术

Research on Undercutting Method of Shield-Driven Underground Expressways in Urban Core Zones with Soft Soil Layers

地下快速路通常需沿主线设置多个匝道与地面道路相接,服务重点区域的到发交通。匝道与主线隧道连接区域往往会成为制约项目的关键因素。软土地区地下快速路主线隧道和匝道通常分别采用盾构法和明挖法实施,分合流处现行施工方案为设置大型异形工作井。大范围明挖对地面交通,地下管线,周边建筑物等产生较大影响。借鉴国内外相关地下道路建设经验,以上海北横通道中山公园工作井为研究背景,结合盾构法地下快速路的特点,分析分合流处非开挖方案的适用性。随后,分别建立荷载结构法和地层结构法三维计算模型,分析主体板壳结构和冻结预支护体系的受力性能。结果表明,主线盾构法隧道分合流处采用局部暗挖方案具有可行性,但是仍然存在一些问题有待深化研究。

Multiple ramps are set up along the main line of underground expressways to connect with the ground road,serving the arrival and departure traffic in urban core zones.Construction of interchanges between ramps and the main tunnel becomes a key restriction of projects.In soft soil areas,the main line and ramps are constructed by shield method and cut-and-cover method,respectively,while interchanges are structured inside ultra-large special-shaped shafts.Large-scale open excavation has great influence on surface traffic,underground pipelines,surrounding buildings and so on.Based on Zhongshan Park shaft in Shanghai Beiheng Tunnel and the characteristics of shield-driven tunnels,taking the construction experience of underground expressways at home and abroad for reference,the applicability of undercutting method in interchange areas is analyzed.Subsequently,3D numerical simulation with loading structure method and stratum structure method are adopted respectively to verify the mechanical performance of the shell structure and the pre-supporting system by Artificial Ground Freezing method(AGF).The results show that it is feasibile that interchanges are structured by undercutting method.However,there are still some issues to be further studied.