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| Research and application of interlaid rock vibration law in drilling and blasting construction of small clear distance tunnel |
| GAO Yufan1，2，FU Hongxian1，2，JI Xiangchen1，2，RONG Xing1，2，YE Zhichao1，2，MENG Zhaowei1，2 |
| (1. School of Civil Engineering and Architecture，Beijing Jiaotong University，Beijing 100044，China；2. Key Laboratory of Urban Underground Engineering of Ministry of Education，Beijing Jiaotong University，Beijing 100044，China) |
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Abstract To make clear the internal blasting vibration characteristics of the interlaid rock in small clear distance tunnels is of great significance to the guarantee construction safety and tunnel stability. Based on a large number of in-situ interlaid rock blasting tests，the main influencing factors of the vibration speed and the evolution of the vibration frequency in the near and far areas of blasting，and the blasting vibration law of different blastholes in different areas were studied. The maximum allowable charge to ensure the safety of the Great Wall was deduced by combining case analysis. The results show that SD = 3.5 is the boundary of near and far blasting，when SD≤3.5，it is near blasting area, and when SD＞3.5，it is far from blasting area，the maximum vibration velocity in the near and far blasting area is produced by the blasting of peripheral holes and cut holes respectively. The PPV value of the center of the interlaid rock in the blasting area is larger than that on both sides，and its attenuation rate is the lowest. The vibration velocity on the surface of the tunnel is larger than that in the middle of the interlaid rock，and the former has a faster attenuation rate. With the increase of SD，the phenomenon that the PPV value in front of the palm face is greater than that behind the tunnel face gradually disappears，and the main frequency of internal vibration of the interlaid rock decreases in a“L”shape. The relationship between the safe charge quantity and distance of the Great Wall based on the regression formula in front of and behind the tunnel face can better guide the blasting construction，and the blasting vibration will not cause damage to the Great Wall.
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2020, Vol. 39 
