Abstract:

The mixing proportion of and key construction technologies for extruded concrete lining of utility tunnels are studied so as to promote the application of utility tunnels with extruded concrete lining in China. The key of the study is to solve the contradiction between the high flowability and long slumpkeeping time of extruded concrete and its early high strength, as well as to solve the problems in the construction of extruded concrete lining. After indoor tests, it is concluded that the mixing proportion of the extruded concrete lining that can meet relevant requirements is W∶C∶F∶Msand∶Maggregate∶Madditive=180∶343∶86∶673∶1 098∶6.4, the extrusion pressure should be controlled at 0.3 MPa, the pressure holding time should be 30 min, the 1 day strength of the concrete can reach more than 10 MPa and the 28 day strength can reach more than 45 MPa. The study result can provide technical support for the construction of extruded concrete lining of utility tunnels in China. 

Key words: utility tunnel, extruded concrete lining (ECL), mixing proportion optimization, pressure control