Research on the Construction Insulation Technology for Large-Volume Open-Cut Tunnel Concrete in Winter
The Baifo Tunnel on Shijiazhuang's Fuxing Street is an open-cut tunnel project requiring 150 000 m3 concrete.In order to address the quality issues associated with large-volume concrete construction in the winter environment ranging from 0 to-15℃,a combination of theoretical analysis and on-site testing was employed to compare and analyze the impact of concrete placement temperature and different insulation measures.A thermal insulation technique suitable for winter concrete construction in the Baifo Tunnel was proposed.The research results indicate that for C45 concrete used in the Baifo Tunnel during winter,the temperature upon discharge from the mixer ranged from 11.7℃to 14.6℃with the temperature fluctuation during concrete placement between 7.4℃and 9.7℃.The tunnel floor,side walls,and ceiling were respectively treated using a combination of"polyurethane+electric heating blanket+quilt","hot air blower",and"electric heating blanket+polyurethane+quilt",and the measured temperature of the concrete interior and surface showed an initial increase followed by a decrease over time.Both the interior and surface temperatures remained above 0℃,and no cracks were observed on the concrete surface.Additionally,on the 7th day,the compressive strength of the concrete in the tunnel floor,sidewalls,and roof reached 36.3 MPa,36.1 MPa,and 35.7 MPa respectively.
open-cut tunnelmunicipal-service tunnelconcreteconstruction in winterinsulation technologycompressive strength
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