Study on Impact Zoning Method and Zoning Control Technique for Construction of Large-diameter Shield Tunnel Adjacent to Viaduct Pile Foundation Group
In order to investigate the impact zoning for large-diameter shield tunnel adjacent to viaduct pile founda-tion group and propose effective comprehensive control measures,the shield construction adjacent to viaduct pile foundation group in the Qibaoshan Station-Huajing Station interval in the Shanghai Airport Link Project is used as an example in this study,and numerical simulation and theoretical analysis are conducted to devise the adjacent im-pact zoning method.Numerical simulation and field test are conducted to investigate the control result and effective-ness of the zoned reinforcement scheme.The following conclusions are drawn:(1)The adjacent impact zoning meth-od devised based on horizontal adjacent degree and vertical adjacent degree can be used for adjacent degree analy-sis of pile foundation group.(2)The combined reinforcement method of MJS reinforcement+isolation pile+sleeve valve pipe grouting below pile cap is proposed for strong impact zone,while the zoning control by isolation pile is proposed for weak impact zone.(3)The isolation pile is mainly meant to isolate the horizontal deformation of soil mass,while the MJS reinforcement and grouting below pile cap are mainly meant to reinforce the soil mass and mini-mize the looseness and slippage of soil mass induced by excavation.(4)The zoning control technique can reduce overall settlement of pile cap by 50.4%and its horizontal displacement by 69.7%,and reduce overall settlement of pier column by 47.7%and its horizontal displacement by 56.0%;the tilt of pier column is kept within 37.1%～46.9%.
Large diameter shield tunnelApproaching constructionViaduct pile foundation groupImpact zoningReinforcement technique
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