复杂环境下浅埋暗挖隧道穿越薄富含水层冻结温度场研究

提出了南京地铁2号线新街口-上海路隧道穿越薄富含水层冻结法止水加固方案,利用ADINA有限元软件对该浅埋暗挖隧道涌水段建立冻结温度场数值模型,分析了冻结管间距、冻结盐水温度、冻结管直径对冻结壁发展速率、冻结壁厚度、平均温度的影响,以此为基础对冻结参数开展优化设计,并获得成功应用。研究结果表明:利用人工冻结技术能够有效解决这一特殊岩土工程难题。为了在支护段获得有效地止水冻土帷幕,冻结管间距应小于等于1m;冻结工程中采取-30℃的盐水温度既能满足需冷量,又能符合经济性要求;采取大直径的冻结管对增加冻土墙厚度与降低冻土壁平均温度的影响并不显著。

Study of thermal field of soil freezing in shallow covered tunnel with subsurface excavation passing through ground with thin aquifer under complex conduction

Artificial freezing water sealing reinforcement method for water-enriching layers of Shang－Xin tunnel of Nanjing metro Line No.2 is proposed. Numerical model of freezing temperature field is built for the water inflowing tunnel by ADINA software. The effects of distance of freezing pipes, brine temperature and diameter of freezing pipes on development of freezing walls, thickness of freezing wall and average temperature are studied. On the basis of this study optimization design is implemented. And the freezing method is successfully applied to the construction. The study demonstrates that the application of artificial freezing can solve this special geotechnical problem. The distance of freezing pipes should less than 1 meter so as to get effective freezing wall. Using brine temperature of -30℃ may not only meet the need of cooling capacity but also meet the economical requirement. There is no significant effect on the thickness of freezing wall and the average temperature by using freezing pipes of large diameter.