地铁隧道下穿淤泥地层工法比选及技术探讨

以广州地铁4号线南延段地铁隧道下穿深厚淤泥层为背景,从方案论证、管片特殊设计以及软基加固等几个方面进行比选和优化,解决淤泥地层盾构隧道偏心受压和工后隧道沉降量大的问题。得出如下结论:淤泥层区间设计应优先选用盾构法,在淤泥层深厚区域结合周边环境及车站选型选用大盾构可降低总成本,减少后期地铁保护难度;在欠固结、存在滑移趋势的淤泥层中应特别重视偏心受压对盾构管片的影响,可通过增加管片配筋提高抗弯、抗裂性能,通过增设变形缝提高结构柔度等措施提高管片受力状况及耐久性。

Comparison of Constructive Method and Technological Discussion on Metro Tunnel in Silt Layer

Based on the southern extension of line4 of Guangzhou subway,the main aim of thispaper is to solve the eccentric compression and after-construction settlement of the shield tunnel in silt layer by means of comparison and optimization of construction method,special design of segments and soft foundation consolidation. The results show that shield tunnel should be selected preferentially for tunnels in silt layer; where the silt layer is very deep,large diameter shield tunnel can be best selected to lower the cost and reduce the difficulties in later metro protection; where located in less consolidated soil with potential slippage,the segments are likely to suffer eccentric compression,which can be avoided by adding more reinforcing bar to improve bending and cracking resistance and by setting additional deformation joints to improve segment stress condition and durability.