超高水压复合地层大直径盾构隧道纵断面优化设计研究

摘要

文章以南京纬三路过江通道超高水压复合地层大直径盾构隧道工程为例，针对原设计方案存在的穿越不利复合地层、入岩深度和长度较大以及水压超高等问题，对隧道施工期和运营期的合理覆土厚度、结构抗浮要求进行了研究；通过采用洞内永久压重方案并结合隧址预测的河床冲刷和现状河床冲淤的观测资料，提出了隧道纵断面优化方案。采用该优化方案，在满足隧道平纵线形指标和施工期及运营期安全的条件下，可降低施工难度和风险、节约工期、提高行车舒适度。%Using the Nanjing Weisan Road river-crossing tunnel, which is a large-diameter shield-driven tunnel in mixed ground with very high water pressure, as an example, the rational overburden thickness and anti-floating requirements for a tunnel structure during the construction and operation phases were studied in order to address such problems as unfavorable mixed ground, great depth and length of the entering rock layer and very high water pressure in the original design option. An optimized profile scheme is presented by combining the permanent weight scheme in the tunnel with the predicted and observed river-bed erosion data. Fewer construction difficulties and risks, a shorter construction period and easier driving can be achieved by adopting this optimization scheme while meeting the requirements for the tunnel plane and longitudinal profile index and assuring tunnel safety during construction and operation.