Observed long-term differential settlement of metro structures built on soft deposits in the Yangtze River Delta region of China.

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From: Canadian Geotechnical Journal(Vol. 57, Issue 6)
Publisher: NRC Research Press
Document Type: Article
Length: 6,537 words
Lexile Measure: 1530L

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Abstract :

In this study, the measured differential settlements of five metro lines built on soft deposits were analyzed. The different structural combinations at various characteristic locations in the metro lines were examined, including at 67 joints of stations and tunnels, 55 connecting passage locations, 4 wind well locations, and at 3 joints of U-shaped grooves and adjacent structures. Moreover, the differential settlement between the track slabs and the bridge piers of a 16.57 km long elevated structure was analyzed. The results showed that the settlements of ~85% of the stations were less than those of adjacent shield tunnels, and the settlements at the connecting passages of ~73% of the tunnels were greater than those on either sides of the tunnel. The wind well exhibited lower settlement than its adjacent tunnels. The settlement of the U-shaped groove was greater than that of its adjacent elevated structure, but was less than those of the cut-and-cover and shield tunnels. Approximately 86% of the track slabs exhibited arch deformation, and the settlements of the bridge piers were greater than those of the track slabs. The stiffness transition between the different structures should be considered in the design of metro structures on soft deposits. Key words: long-term settlement, differential settlement, stiffness transition. Dans cette etude, les tassements differentiels mesures de cinq lignes de metro construites sur des depots meubles ont ete analyses. Les differentes combinaisons structurelles a differents emplacements caracteristiques des lignes de metro ont ete examinees, notamment a 67 jonctions de gares et de tunnels, a 55 emplacements de passages, a 4 emplacements de puits de vent et a 3 joints de rainures en U et de structures adjacentes. De plus, le tassement differentiel entre les dalles de la voie et les piliers du pont d'une structure elevee de 16,57 km de long a ete analyse. Les resultats ont montre que les implantations de ~85 % des stations etaient inferieures a celles des tunnels a boucliers adjacents et que les implantations aux passages de connexion de ~73 % des tunnels etaient plus grandes que celles situees de part et d'autre du tunnel. Le puits de vent presentait un tassement plus faible que ses tunnels adjacents. Le tassement de la rainure en forme de U etait plus important que celui de la structure surelevee adjacente, mais inferieur a celui des tunnels de tranchee couverte et de boucliers. Environ 86 % des dalles de la voie presentaient une deformation de la voute, et les tassements des piliers du pont etaient plus grands que ceux des dalles de la voie. La transition de rigidite entre les differentes structures doit etre prise en compte dans la conception des structures de metro sur des depots mous. [Traduit par la Redaction] Mots-cles : reglement a long terme, reglement differentiel, transition de rigidite.

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Gale Document Number: GALE|A627109632