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Analysis of the Mechanical Response in the Construction of Large-Span Mined Metro Stations by the Arch-Cover Method
(1 College of Transportation Engineering, Dalian Maritime University, Dalian 116026; 2 Construction Branch of Shanghai Civil Engineering Group Co., Ltd. of CREC, Shenyang 110000)
Abstract Based on the large-span shallow mined Shikui Road Station of Dalian Metro Line 5, this paper uses the FLAC3D finite difference software for 3D numerical modeling, conducts a detailed analysis of the changes of ground settlement, lining and surrounding rock stress during the construction with the arch-cover method, proposes corresponding construction measures according to the characteristics of the mechanical response of each construction stage, and optimizes the reasonable excavation spacing of the pilot tunnel with large section. Finally, the results are compared with the actual monitoring data. The results show that the excavation of the main pilot tunnel with large section is the main factor leading to the ground settlement, which basically remains stable after the completion of the construction of the secondary lining at the vault; the excavation of the single-sided pilot tunnel has an obvious asymmetrical loading effect, and it should strictly follow the construction sequence of "the side first before the middle";the removal of the temporary support and the middle diaphragm has a significant impact on the initial support and surrounding rock stress, and measures such as segmented removal, cross removal and bolt installation instead of support can be taken to ensure the stability of the structure; the excavation spacing of the main pilot tunnel with large section has an obvious impact on the ground settlement, and the reasonable spacing should be controlled within the range of 20~35 m. The numerical calculation results are in good agreement with the field monitoring data, which can provide references for similar engineering practices.
Abstract：
Based on the large-span shallow mined Shikui Road Station of Dalian Metro Line 5, this paper uses the FLAC3D finite difference software for 3D numerical modeling, conducts a detailed analysis of the changes of ground settlement, lining and surrounding rock stress during the construction with the arch-cover method, proposes corresponding construction measures according to the characteristics of the mechanical response of each construction stage, and optimizes the reasonable excavation spacing of the pilot tunnel with large section. Finally, the results are compared with the actual monitoring data. The results show that the excavation of the main pilot tunnel with large section is the main factor leading to the ground settlement, which basically remains stable after the completion of the construction of the secondary lining at the vault; the excavation of the single-sided pilot tunnel has an obvious asymmetrical loading effect, and it should strictly follow the construction sequence of "the side first before the middle";the removal of the temporary support and the middle diaphragm has a significant impact on the initial support and surrounding rock stress, and measures such as segmented removal, cross removal and bolt installation instead of support can be taken to ensure the stability of the structure; the excavation spacing of the main pilot tunnel with large section has an obvious impact on the ground settlement, and the reasonable spacing should be controlled within the range of 20~35 m. The numerical calculation results are in good agreement with the field monitoring data, which can provide references for similar engineering practices.
ZHANG Zilong1 JIANG Annan1 YU Hai2 WANG Feng2
.Analysis of the Mechanical Response in the Construction of Large-Span Mined Metro Stations by the Arch-Cover Method[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(3): 139-146
2021, Vol. 58 