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Impact Zoning and Dynamic Response to Blasting Vibration in Adjacent Tunnel under Hard Rock Strata
(1. Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University School of Civil Engineering, Chengdu 610031; 2. The Third Engineering Co., Ltd. of China Railway 22nd Bureau Group Corporation Limited,Xiamen 361000)
Abstract To investigate how the blasting of overlapped tunnels affects adjacent existing tunnels in hard rock strata, a study is carried out on the impact zoning of the blasting vibration and dynamic response of new tunnels based on the "frequency-velocity" criterion specified in China′ s standards for blasting vibrations, with the new Damaoshan No.1 Tunnel and the existing Xinliutang No.1 Tunnel on Fuzhou-Xiamen Passenger Dedicated Line as the study case. First, the calculation parameters are obtained through triaxial tests and the Hoek-Brown criterion. Second, the blasting vibration pattern of new tunnels under different cases is studied and the impact zoning of the blasting vibration is obtained. Finally, a 3D finite element model is established to investigate the dynamic response pattern of the existing tunnel when the new tunnel is being blasted directly below the existing tunnel. The results show that: (1) the impact of the project′ s blast vibration can be zoned through the maximum vibration attenuation curve on the blast face and it can be determined that the existing tunnel is in the weak impact zone; (2) The impact range of blasting in the up and down directions is greater than that in the left and right directions, and the total impact zones of blasting vibration can be obtained for single-track railway tunnels under hard rock strata; (3) The impact range of blasting on the existing tunnel above the unexcavated section is greater than that on the excavated section, and because of media reflection, the attenuation of the vibration speed of the existing tunnel above the excavated section is slow; (4)the correctness of the numerical simulation is verified with the field monitoring results, and it is found that the deformation and stress of the existing tunnel structure both meet the requirements for impact control.
Abstract：
To investigate how the blasting of overlapped tunnels affects adjacent existing tunnels in hard rock strata, a study is carried out on the impact zoning of the blasting vibration and dynamic response of new tunnels based on the "frequency-velocity" criterion specified in China′ s standards for blasting vibrations, with the new Damaoshan No.1 Tunnel and the existing Xinliutang No.1 Tunnel on Fuzhou-Xiamen Passenger Dedicated Line as the study case. First, the calculation parameters are obtained through triaxial tests and the Hoek-Brown criterion. Second, the blasting vibration pattern of new tunnels under different cases is studied and the impact zoning of the blasting vibration is obtained. Finally, a 3D finite element model is established to investigate the dynamic response pattern of the existing tunnel when the new tunnel is being blasted directly below the existing tunnel. The results show that: (1) the impact of the project′ s blast vibration can be zoned through the maximum vibration attenuation curve on the blast face and it can be determined that the existing tunnel is in the weak impact zone; (2) The impact range of blasting in the up and down directions is greater than that in the left and right directions, and the total impact zones of blasting vibration can be obtained for single-track railway tunnels under hard rock strata; (3) The impact range of blasting on the existing tunnel above the unexcavated section is greater than that on the excavated section, and because of media reflection, the attenuation of the vibration speed of the existing tunnel above the excavated section is slow; (4)the correctness of the numerical simulation is verified with the field monitoring results, and it is found that the deformation and stress of the existing tunnel structure both meet the requirements for impact control.
LIU Jiaming1 ZHANG Junru1 WANG Zhiyong1 JING Yawen1 JIANG Manlin1 TAN Yumei1 CHEN Kegang2
.Impact Zoning and Dynamic Response to Blasting Vibration in Adjacent Tunnel under Hard Rock Strata[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(2): 125-137
2023, Vol. 60 