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Geomechanics and Engineering
  Volume 15, Number 2, June10 2018, pages 745-754
DOI: http://dx.doi.org/10.12989/gae.2018.15.2.745
 


Determination of equivalent blasting load considering millisecond delay effect
Zhan-Ping Song, Shi-Hao Li, Jun-Bao Wang, Zhi-Yuan Sun, Jing Liu and Yu-Zhen Chang

 
Abstract
    In the analysis of the effects of rock tunnel blasting vibration on adjacent existing buildings, the model of simplified equivalent load produces higher calculation result of vibration, due to the lack of consideration of the millisecond delay effect. This paper, based on the static force equivalence principle of blasting load, proposes a new determination method of equivalent load of blasting vibration. The proposed method, based on the elastic-static force equivalence principle of stress wave, equals the blasting loads of several single blastholes in the same section of millisecond blasting to the triangle blasting load curve of the exploded equivalent elastic boundary surface. According to the attenuation law of stress wave, the attenuated equivalent triangle blasting load curve of the equivalent elastic boundary is applied on the tunnel excavation contour surface, obtaining the final applied equivalent load. Taking the millisecond delay time of different sections into account, the time-history curve of equivalent load of the whole section applied on the tunnel excavation contour surface can be obtained. Based on Sailing Tunnel with small spacing on Sanmenxia-Xichuan Expressway, an analysis on the blasting vibration response of the later and early stages of the tunnel construction is carried out through numerical simulation using the proposed equivalent load model considering millisecond delay effect and the simplified equivalent triangle load curve model respectively. The analysis of the numerical results comparing with the field monitoring ones shows that the calculation results obtained from the proposed equivalent load model are closer to the measured ones and more feasible.
 
Key Words
    tunnel; millisecond blasting; delay effect; equivalent load
 
Address
Zhan-Ping Song: 1.)School of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an, China
2.)Research Center of the Tunnel and Underground Structure Engineering, Xi\'an University of Architecture and Technology, Xi\'an, China

Shi-Hao Li, Jun-Bao Wang, Jing Liu and Yu-Zhen Chang: School of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an, China

Zhi-Yuan Sun: Chinese Railway Bridge Engineering Bureau Group Co. Ltd., Tianjin, China
 

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