ISSN 2096-4498
CN 44-1745/U
ISSN 2096-4498
CN 44-1745/U
Case Study on Parallel Cut in Vibrationreducing Blasting of Hard Rock Tunnel in Urban Area
Received date: 2013-04-23
Revised date: 2014-03-19
Online published: 2014-06-16
Cut method not only affects the tunnel excavation efficiency, but also affects the blasting vibration control effect. No. 3 bid section of No. 3 line of Phase 1 project of Qingdao Metro crosses underneath an existing hospital. In the paper, the blasting in the tunneling under the hospital is studied. 3 parallel cut methods, i.e., smalldiameter single hollow hole cut method, largediameter single hollow hole cut method and largediameter double hollow hole cut method, are analyzed in terms of tunneling advance rate, blasting hole utilization rate and peak value of vibration velocity of monitoring point at ground surface above the working face. Conclusions drawn are as follows: 1) Under the same conditions, the largediameter single hollow hole cut method is superior to the other 2 cut methods in terms of blasting hole utilization rate and vibration control. The largediameter single hollow hole cut method is used in the blasting of tunnel underneath the hospital and good effect has been achieved, with the vibration velocity being controlled under 2 cm/s; 2) The tunnel excavation efficiency and vibration control effect of parallel cut method are related to the ratio between the distance from the charged hole to the hollow hole (l) and the diameter of the hollow hole ().
Key words: parallel cut; blasting; vibration; excavation; largediameter hollow hole
WANG Juntao , WANG Hailiang , YANG Qing . Case Study on Parallel Cut in Vibrationreducing Blasting of Hard Rock Tunnel in Urban Area[J]. Tunnel Construction, 2014 , 34(6) : 564 -568 . DOI: 10.3973/j.issn.1672-741X.2014.06.011
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