Vibration control of blasting excavation of large cross-section highway tunnel over metro line
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GMGDA 2019
Vibration control of blasting excavation of large cross-section highway tunnel over metro line Qinghua Qin 1 & Jun Zhang 2 Received: 30 June 2020 / Accepted: 12 August 2020 # Saudi Society for Geosciences 2020
Abstract The blasting excavation of the new tunnel may cause damage to the adjacent tunnel. Taking the Hongshi road tunnel in Chongqing as a research object, the paper analyzed the influence of the maximum charge on the vibration speed of the existing tunnel by comparing the influence of adjacent tunnel blasting team on the existing tunnel simulated by ANSYS/LS-DYNA with the actual monitoring results. The results show that when adopting the “three steps + invert” four steps excavation, the maximum charge quantity of each excavation step is 56.8 kg, 40.2 kg, 37.1 kg, and 21.6 kg, and the combined vibration velocity of the control measuring points is less than 1.5 cm/s. All meet the design requirements. The vibration velocity of the blasting side of the existing subway tunnel is mainly in the horizontal direction and relatively small in the vertical direction. With the increase of distance from the blasting point, the maximum vibration velocity is the charge quantity of large sections and can be increased gradually. Keywords Large-section tunnel . Adjacent tunnel . Finite element method . Numerical simulation . Blasting vibration
Introduction As urban infrastructure expanding continuously and rapidly, the construction of new structures will inevitably affect existing ones. The excavation causes blasting vibration and the redistribution of surrounding rock stress, thus leading to the potential structural safety issue of the existing tunnel during the construction process. The closer the distance is, the more prominent the influence is. Relevant research points out that when the vibration velocity caused by blasting occurs on the sidewall of the existing tunnel, it reaches the largest level. The more stable the surrounding rock is, the smaller the vibration velocity is. When the spacing is less than one time of the tunnel diameter, the vibration velocity of the tunnel lining may exceed the allowable value, while the relationship between the vibration This article is part of the Topical Collection on Geological Modeling and Geospatial Data Analysis * Jun Zhang [email protected] 1
Chongqing Rail Transit (Group) Co., Ltd, Chongqing 401120, China
2
Chongqing Municipal Research Institute of Design, Chongqing 400020, China
velocity of the surrounding rock and the distance to the blasting source is nonlinear (Bi and Zhong 2004). Sidewall, arch foot, arch crown, and other parts of the blasting side of the built tunnel are the most severely impacted parts of the built adjacent tunnel when conducting the upper loose blasting. During the construction, it is important to monitor the blasting side of the tunnel (Ouyang and Shuai 2009). The maximum blasting charge remains unchanged, the better the surrounding rock quality, and the greater the thickness of the intermediate rock, the smaller the vibration spe
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