Tunnel millisecond-delay controlled blasting based on the delay time calculation method and digital electronic detonators to reduce structure vibration effects

RESEARCH ARTICLE Tunnel millisecond-delay controlled blasting based on the delay time calculation method and digital electronic detonators to reduce structure vibration effects Xiaoming Guan ID1☯, Caixia Guo2☯, Ben Mou1*, Leilei Shi3 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Department of Civil Engineering, Qingdao University of Technology, Qingdao, P.R. China, 2 Department of Civil Engineering, Tsinghua University, Haidian District, Beijing, P.R. China, 3 Beijing, Municipal Construction Engineering Co., Ltd., Beijing, P.R. China ☯ These authors contributed equally to this work. * Abstract OPEN ACCESS Citation: Guan X, Guo C, Mou B, Shi L (2019) Tunnel millisecond-delay controlled blasting based on the delay time calculation method and digital electronic detonators to reduce structure vibration effects. PLoS ONE 14(3): e0212745. https://doi. org/10.1371/journal.pone.0212745 Editor: Wajid Mumtaz, Zapadoceska univerzita, CZECH REPUBLIC Received: May 4, 2018 Accepted: February 9, 2019 Published: March 22, 2019 Copyright: © 2019 Guan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper. Funding: This work is supported by the National Natural Science Foundation of China (Project No. 51708317 to XG), http://www.nsfc.gov.cn/; the Chinese Postdoctoral Science Foundation (2017M621095 to XG), http://jj.chinapostdoctor. org.cn/V1/Program3/Default.aspx and the Natural Science Foundation of Shandong Province (ZR2016EEB27 to XG, ZR2016EEB38), http://www. sdstc.gov.cn/. The funders had role in the study The reasonable delay time of millisecond-delay blasting using digital electronic detonators can significantly reduce the vibration effects induced by tunnel blasting. This study proposes a method for calculating the delay time for cut holes, easer holes and periphery holes, considering the rocks breaking effect as well as wave superposition theory. And then according to the actual layout diagram of the tunnel holes, the delay time calculation formulas of different holes are put forward. Then the delay times were calculated according to the formulas and applied in the field tests. The velocities, rocks breaking and wave superposition cancellation of the vibration using different delay times are analyzed with digital electronic detonators. Then the optimum delay times of different holes were obtained and applied to New Hongyan tunnel project. The velocity and frequency of the vibration with digital electronic detonators are analyzed, compared with non-electronic detonators. The effects of charge and delay time on the velocity and principal frequency of a blasting seismic wave are discussed. The results indicate that the delay time for the holes must be prioritized to achieve breaking effects in the rock with the simultaneous formation of a new free surface, next considering the wave superposition cancellation. When the delay time of cut holes was 5 ms, the rocks breaking effect and wave superposition cancellation effect both worked well. The velocity of the vibration induced by the cut holes blasting was about only 0.46–0.51 cm/s. When the delay time was 6 ms or much longer, the rocks breaking effect would fail. With regard to the easer holes and periphery holes, the optimum delay time of them were all 5ms. The vertical peak particle velocity was reduced from 2.974 cm/s to 0.901 cm/s with digital electronic detonators. Therefore, the velocity had decreased by 69.70% than non-electronic detonators, which was caused by reducing the single simultaneous explosive charge and setting optimum delay time. The proposed delay time calculation method is demonstrated to be sufficiently accurate and can thus be used as a guideline to reduce tunnel blasting vibrations. PLOS ONE | https://doi.org/10.1371/journal.pone.0212745 March 22, 2019 1 / 25 Tunnel controlled blasting using digital electronic detonators design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: Shi Leilei is affiliated with Beijing N0.4 Municipal Construction Engineering Co., Ltd. Our company confirms that this commercial affiliation does not alter our adherence to all PLOS ONE policies on sharing data and materials. 1. Introduction Complex environmental tunnels that pass through dense buildings are constructed using the drilling and blasting method are becoming increasingly popular [1,2,3]. Tunnel blasting vibration often causes damage to surrounding buildings and affects the daily work and lives of nearby inhabitants [4,5,6,7]. Therefore, reasonable measures must be taken to control the blasting vibrations. The main concept of the millisecond blasting technique is to control the detonation time and ignition sequence of detonators to achieve the expected vibration suppression effectiveness [8,9,10]. At present, non-electric millisecond detonators are widely used in tunnel blasting vibration control; however, such detonators have many limitations. Because non-electric millisecond detonators are detonated at the same time with several holes, the blasting vibration can be reduced by reducing the cyclical footage, using small charges and dividing the blasting. However, this approach reduces the construction efficiency and extends the construction period. When using the millisecond blasting technique, the delay time accuracy of non-electric detonators is rather low, with a delay error of approximately ± (10–150) milliseconds, because non-electric detonators achieve millisecond delay by controlling the chemical burning rate [11]. Therefore, blasting with non-electric detonators causes uncertainties and instabilities in blasting vibration control that prevent waveform interference from achieving the desired vibration reduction. With the development of high-precision digital electronic detonators, fine controlled blasting has been successfully applied to the construction of complex environmental tunnels. Digital electronic detonators achieve accurate millisecond delay by using an integrated circuit chip. The scope of the delay time is approximately 1 ms to 16 s, and the delay error is only approximately 0.1 ms. Digital electronic detonators can accurately achieve time delay ignition according to the needs of the conditions on site. A strong rock-crushing effect can be obtained using digital electronic detonators, and damage to structures near the tunnel induced by tunnel blasting under complex environmental conditions can be reduced [12,13]. Moreover, the use of electronic detonators leads to not only a smaller Excavation Damaged Zone (EDZ) but also a lower degree of rock breakage in the EDZ [14]. The use of digital electronic detonators has led to social, environmental and economic benefits. When (...truncated)