Abstract Selection and optimization of construction sequence of the small-spacing and overlapped tunnels are key factors affecting construction safety and progress. Based on the four small-spacing and overlapped bored tunnels of Line 4I and Line 9 on Chongqing Rail Transit, the influences of four different construction sequences on ground surface settlement, internal force and deformation of tunnel structure were studied using finite element simulation. The results show that the construction of overlapped mined tunnel causes settlement of ground surface, the closer the overlapped mined tunnels are, the larger the ground surface settlements are; the“lower-upper”construction sequence is superior to the“upper-lower”sequence for controlling ground surface settlement, tunnel crown settlement and lining stress, and construction sequence of the following tunnels has little effect; for the four small-spacing and overlapped mined tunnels, it is optimal to adopt a construction sequence of“lower-upper and left-right”with the ground surface settlement and crown settlement no more than 10 mm, meeting the requirements of technical standards concerned, and the variation law of settlement is consistent with the results of finite element simulation.
Abstract：
Selection and optimization of construction sequence of the small-spacing and overlapped tunnels are key factors affecting construction safety and progress. Based on the four small-spacing and overlapped bored tunnels of Line 4I and Line 9 on Chongqing Rail Transit, the influences of four different construction sequences on ground surface settlement, internal force and deformation of tunnel structure were studied using finite element simulation. The results show that the construction of overlapped mined tunnel causes settlement of ground surface, the closer the overlapped mined tunnels are, the larger the ground surface settlements are; the“lower-upper”construction sequence is superior to the“upper-lower”sequence for controlling ground surface settlement, tunnel crown settlement and lining stress, and construction sequence of the following tunnels has little effect; for the four small-spacing and overlapped mined tunnels, it is optimal to adopt a construction sequence of“lower-upper and left-right”with the ground surface settlement and crown settlement no more than 10 mm, meeting the requirements of technical standards concerned, and the variation law of settlement is consistent with the results of finite element simulation.
WANG Meng SHI Mengxiao XU Manji WU Wenpeng
.Study on Construction Sequence of Four Overlapped Bored Tunnels with Small-spacing[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(3): 139-146
2019, Vol. 56 