Laws and Numerical Analysis of Surface Deformation Caused by Excavation of Large Diameter Slurry Shield in Upper-Soft and Lower-Hard Composite Stratum
- Release time:2024-08-09
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Affiliation of Author(s):
土木工程学院
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Journal:
Buildings
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Key Words:
shallow soil; large-diameter slurry shield; composite strata; surface deformation; numerical simulation
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Abstract:
Due to the large cross-section design of large-diameter shield tunnels, most of the rocks
and soils it crosses are composite strata with upper soft and lower hard. In order to reduce the
construction cost of shield working shafts, large-diameter shield launching is usually buried at a
shallow depth. Based on the typical large-diameter slurry shield tunnel, the following research
results were obtained according to field monitoring and PLAXIS 3D finite element simulation.
(1) The electronic level is used to monitor the surface settlement, and the field monitoring data were
obtained; the surface settlement duration curve at the axis of the shield tunnel during the construction
period can be divided into four stages: pre-deformation, shield passing, shield tail exit and shield
moving away, of which the surface settlement accounts for the largest proportion during the shield
passing. (2) In order to ensure the accuracy of the numerical simulation results, the linear shrinkage
of the shield needs to be considered in the modeling. (3) The maximum surface settlement value
at the center of the tunnel increases with the increase of the support pressure; when the support
pressure exceeds 300 kPa, the surface uplift and the settlement caused by the formation loss will
offset, and the surface settlement will decrease instead. The maximum surface settlement value is
inversely proportional to the grouting pressure, but with the increase of the grouting pressure, the
maximum uplift of the surface continues to increase. (4) With the numerical simulation of excavation
step construction, the surface uplift increases with the increase of grouting pressure and shield radius,
and decreases with the increase of shield buried depth.
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First Author:
meiyuan
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Indexed by:
Journal paper
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ISSN No.:
2075-5309
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Translation or Not:
no
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Date of Publication:
2022-09-13
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