Abstract
Building deformations are not only closely related to the distance from the building to metro-station excavation but also related to the relative positions of the building and metro-station excavation. Building deformations can be predicted using ground surface settlement profiles. Based on typical geological parameters of Nanjing metro-station excavation, ground surface settlements were numerically simulated by auxiliary planes perpendicular and parallel to the excavation and by angled auxiliary planes at the excavation corner. Results show that the ground surface settlement profiles in auxiliary planes are closely related to the relative positions of the auxiliary planes and the metro-station excavation. Partitioning of ground surface settlements was proposed according to the three types of ground surface settlement profiles; furthermore, bending deformation and torsional deformation regularities of surrounding buildings were analyzed, and an estimation method for building settlements was developed. Finally, field-monitored settlement data of 21 buildings in different zones were compared with the estimated settlement data, and the application of the settlement estimation method to different types of foundations was analyzed. The results of this study can serve as reference for metro-station deep excavation construction and protection of surrounding buildings.
Highlights
Metro-station deep excavations are generally located in bustling areas of a city. e excavation design should meet the strength and stability requirements of the support structure and the deformation-control requirements of the surrounding environment [1]
(1) For the ground surface settlements, the surface settlement profiles in the perpendicular auxiliary plane are all trough-shaped at the short-side center, long-side center, and corner 45° direction. e maximum settlement position of the short side is closer to the diaphragm wall than that of the long side and the corner 45° direction, and the maximum settlement positions of the long side and the corner 45° direction are essentially the same
When the distance of the parallel auxiliary plane to the diaphragm wall is within 0.5H, the ground surface settlements in the parallel auxiliary plane increase when they cross the excavation corner, and the settlement profile is trough-shaped
Summary
Metro-station deep excavations are generally located in bustling areas of a city. e excavation design should meet the strength and stability requirements of the support structure and the deformation-control requirements of the surrounding environment [1]. Ground surface settlements can be studied through auxiliary planes perpendicular and parallel to the excavation, as well as through angled auxiliary planes at the excavation corner (Figure 1). Li et al [17] studied ground surface settlement profiles by analyzing field-monitoring data of 30 station excavations in the construction of Nanjing Metro Line 3, Line 10, and Line S8. The modified Cam-clay model was adopted with typical geological parameters in the Nanjing region, and the 3D characteristics of ground surface settlements resulting from station excavation were numerically analyzed using FLAC3D. Li et al [17] reported that three types of ground surface settlement profiles suitable for different zones (zones A, B, and C) around the excavation were obtained in the construction of Nanjing Metro Line 3, Line 10, and Line S8. It should be noted that the three surface settlement profiles reported by Li et al [17] were based on the greenfield ground settlement. us, the greenfield ground settlement was used to assess the building deformation, and there was no consideration of the excavation-building interaction
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