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Study on Effects of Group Foundation Pits Excavation on Heaving/Settlement of Adjacent Metro Tunnel in Operation
(1 School of Civil Engineering, Beijing Jiaotong University, Beijing 100044; 2 China Railway Construction & Investment Group Co., Ltd., Shenzhen 518055; 3 School of Civil Engineering, Central South University, Changsha 410075)
Abstract The Che Kung Temple interchange project of Shenzhen Metro is used as an example in this paper to study the heaving/settlement laws and the displacement control measures for the adjacent metro tunnel in operation which is effected by excavation of group foundation pits. In order to control the displacement of existing tunnel and track structure, the deformation control standards for track structure in each construction step of group foundation pits are set by means of scheme optimization, theoretical analysis and numerical simulation based on the distribution principle of structure displacement. With the unloading effect induced by foundation pit excavation, the displacement superimposed effect of adjacent existing tunnel is noticeable, therefore the excavation and dewatering of the pit are the key steps among the construction sequence of group foundation pits. Foundation pit dewatering is a favorable factor for controlling the heaving of underneath tunnel, while it is an unfavorable factor for controlling the horizontal deformation. Consequently, the displacement reference values of the underground structure in different orientations shall be taken into account as for the reasonable dewatering measures in the progress of design and construction. The actual measurements show that during the excavation of group foundation pits, deformation of existing subway structure is not beyond the specific standard, the deformation control standards are reasonable and the engineering measures are effective.
Abstract：
The Che Kung Temple interchange project of Shenzhen Metro is used as an example in this paper to study the heaving/settlement laws and the displacement control measures for the adjacent metro tunnel in operation which is effected by excavation of group foundation pits. In order to control the displacement of existing tunnel and track structure, the deformation control standards for track structure in each construction step of group foundation pits are set by means of scheme optimization, theoretical analysis and numerical simulation based on the distribution principle of structure displacement. With the unloading effect induced by foundation pit excavation, the displacement superimposed effect of adjacent existing tunnel is noticeable, therefore the excavation and dewatering of the pit are the key steps among the construction sequence of group foundation pits. Foundation pit dewatering is a favorable factor for controlling the heaving of underneath tunnel, while it is an unfavorable factor for controlling the horizontal deformation. Consequently, the displacement reference values of the underground structure in different orientations shall be taken into account as for the reasonable dewatering measures in the progress of design and construction. The actual measurements show that during the excavation of group foundation pits, deformation of existing subway structure is not beyond the specific standard, the deformation control standards are reasonable and the engineering measures are effective.
LIU Ji-Qiang-1,
2 ,
欧Xue-Feng-3 etc
.Study on Effects of Group Foundation Pits Excavation on Heaving/Settlement of Adjacent Metro Tunnel in Operation[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(4): 81-87
2014, Vol. 51 