Subway Cross Passage Artificial Freezing Temperature Field in Pebble Stratum with High Velocity Flow
The excavation of subway cross passage is often disturbed by groundwater,and the artificial ground freezing method has become the preferred method for the construction of cross passage in water-rich stratum by virtue of its excellent water sealing and adaptability.Relying on the freezing project of 1# cross passage between Suzhou Qiao Station and Renmin University.Station of Beijing Metro Line 12,the development law of stratum temperature field and the pressure of depressurization hole was studied through field monitoring.The closure characteristics of freezing curtain were analyzed to determine the weak position of freezing wall of high flow velocity stratum.The results show that the temperature of brine decreases rapidly in the early stage of freezing,then the rate of decrease slows down and finally the temperature stabilizes below-28 ℃.The temperature at the junction of soil and tunnel lining in the thermometric holes is higher than that inside of the soil,and the temperature of the freezing wall at the upstream of the seepage is higher than that at the downstream,so these areas should pay more attention to monitor.When freezing to 59 d,based on the actual rate of decrease in temperature,the calculation method of the freezing wall thickness in different stages is used to obtain the minimum thickness of the freezing wall in different section is 2 495.2 mm.At the same time,the pressure of depressurization hole has been fully released and kept stable,the frozen wall no longer develops,and meets the requirements of cross passage excavation.The research results can provide theoretical support for the selection of artificial freezing parameters and monitoring in high flow velocity strata.
cross passageartificial ground freezing methodtemperature fieldfreezing wall thicknessfrost heaving force
万方数据
维普
