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Model Test on the Stability of the Surrounding Rock of a Tunnel Constructed by the Arch-Cover Method
(1 College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100; 2 School of Civil Engineering, Beijing Jiaotong University, Beijing 100044; 3 Qiangdao Municipal Administration, Qingdao 266100)
Abstract In this paper, surface deformation law and the force applied on surrounding rock during the arch-cover method of tunnel construction are studied by a large-scale model test. The results show that surface subsidence undergoes three settlement phases in the process of tunnel excavation: slow settlement, fast settlement, and slow settlement again. The fast development of surface subsidence occurred during middle pilot tunnel excavation and vertical bracing dismantlement. Excavation of the bottom surrounding rock had little impact on surface deformation when the secondary lining at the crown was completed. The load-releasing process of the surrounding rock at each part of the monitoring section was quite different while the working face was advancing, and the load-releasing speed at the tunnel crown was greater than that at the arch springing and sidewall. Excavation of the middle pilot tunnel at the tunnel crown and dismantlement of the temporary support resulted in a secondary pressure release of the stable surrounding rock. Radial convergence of the surrounding rock was well controlled, which is attributed to its self-supporting capacity and immediate support. Is it is suggested that crown settlement be considered a main criterion for judging the stabilization of the surrounding rock in tunnels characterized by the arch-cover method.
Abstract：
In this paper, surface deformation law and the force applied on surrounding rock during the arch-cover method of tunnel construction are studied by a large-scale model test. The results show that surface subsidence undergoes three settlement phases in the process of tunnel excavation: slow settlement, fast settlement, and slow settlement again. The fast development of surface subsidence occurred during middle pilot tunnel excavation and vertical bracing dismantlement. Excavation of the bottom surrounding rock had little impact on surface deformation when the secondary lining at the crown was completed. The load-releasing process of the surrounding rock at each part of the monitoring section was quite different while the working face was advancing, and the load-releasing speed at the tunnel crown was greater than that at the arch springing and sidewall. Excavation of the middle pilot tunnel at the tunnel crown and dismantlement of the temporary support resulted in a secondary pressure release of the stable surrounding rock. Radial convergence of the surrounding rock was well controlled, which is attributed to its self-supporting capacity and immediate support. Is it is suggested that crown settlement be considered a main criterion for judging the stabilization of the surrounding rock in tunnels characterized by the arch-cover method.
YANG Zhong-Nian-1,
Ji-Zhao-Qi-1,
Liu-Quan-Wei-2 etc
.Model Test on the Stability of the Surrounding Rock of a Tunnel Constructed by the Arch-Cover Method[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(5): 85-91
2014, Vol. 51 