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Analysis on Influence of Blasting of Underlying of Tunnel on Surrounding Rock of Existing Tunnel-type Anchorage Based on Numerical and Theory Method

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DOI: 10.25236/icemit.2019.033

Author(s)

Wang Lianbin

Corresponding Author

Wang Lianbin

Abstract

Due to the constraints of construction period and site conditions, in order to ensure the stability of the surrounding rock of existing tunnel-type anchorage and the safety of bridge, it is necessary to study the influence of blasting construction of underlying tunnel on the surrounding rock of the existing tunnel-type anchorage. Based on the methods of numerical methods and theoretical analysis, this paper systematically analyzed the influence of underpass tunnel construction on the surrounding rock of the tunnel-type anchorage from the aspects of loose circle of the surrounding rock. The results show that when underlying tunnel blasting, the peak velocity of the top arch monitoring points in each section of the right underlying tunnel specifically is largest. For the blasting of the upper steps, it is necessary to focus on monitoring the vibration speed of the top arch. The total peak velocity of the monitoring point of the anchorage does not exceed 1 cm/s, which is smaller than the allowable vibration velocity of the particle which is stipulated by the blasting and meets the stipulated requirements. Based on the elasto-plastic theory, Hoek-Brown strength criterion is used to calculate the thickness of the loose circle of top arch about 2.04m. Therefore, the blasting of underlying tunnel has less influence on the surrounding rock of existing tunnel-type tunnel.

Keywords

Underlying tunnel, tunnel-type anchorage, blasting, loose circle, dynamic analysis