It is an effective method to construct a temporary shield maintenance environment at the bottom of rivers by isolating connection with the external groundwater after horizontal freezing in the shield mud tank.However,the existing research results cannot provide a reference for the evaluation of the freezing construction process.Based on the cross-river water supply corridor project of Xinjizhou in Nanjing,the temperature distribution characteristics and influence law in the process of forming frozen soil in shield mud tank were studied.The results show that through the relay heat exchanger of the shield working face,the ground low-temperature brine can be pumped into the freezing pipe with a small circulating pressure,thereby reducing the risk of brine leakage in the freezing pipe.During the stable freezing stage,the brine temperature of the working face was about 2.5℃ higher than the ground temperature.The change process of the temperature at the end of the freezing pipe during the construction process is basically the same,but due to the difference in the heat absorption capacity of the strata around the freezing pipe,the tempera-ture at the end of the freezing pipe with a large spacing was about 1℃ higher.The difference between the thermal conductivity and the heat dissipation coefficient of the shield structure steel will affect the cold transfer process,resulting in the temperature of the frozen soil around the shield cutterhead about 3℃ lower,while the heat dissipation of the shield panel causes the temperature of the frozen soil at the corresponding position about 4℃ higher.Under the condition that the maximum spacing of the horizontal freezing pipe was 3.12 m,the shield mud tank can be frozen completely after 80 days of freezing,so that the construction condi-tions for opening the shield mud tank in emergency maintenance can be realized.
关键词
富水地层/泥水平衡盾构/冻结温度场/越江供水廊道工程
Key words
water-rich stratum/mud-water balance shield/freezing temperature field/cross-river water supply corridor project
维普
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