Research on Blasting Design and Safety Control for Tunnel Reconstruction and Expansion
To explore the design scheme and safety control of tunnel renovation and expansion projects,a case a-nalysis of a certain national highway tunnel project based on the theory of tunnel blasting was conducted.The tun-nel blasting construction plan,blasting parameter selection and blasting network design were systematically studied,and the safety control of tunnel blasting was explored.The calculated engineering blasting vibration velocity was in accordance with the specification,the on-site blasting situation was good,which verified the accuracy of the blas-ting design scheme.The main research conclusions are as follows:(1)The strength of tunnel support,advanced support,and excavation methods should be strengthened synchronously with the deterioration of surrounding rock conditions.Compared with the blasting design of split tunnel,the blasting design of double arch tunnels and open cut tunnels need to be further optimized and the connection position of tunnels needs to be paid attention to;(2)During blasting,pre splitting and smooth blasting methods are used for the side walls and top respectively.There should be differences in blasting parameters under different surrounding rock conditions and construction condi-tions.Deep hole blasting is mainly used for the main blasting hole,while shallow hole blasting is mainly used for subgrade of open tunnel excavation section and tunnel step;(3)During blasting design,the layout of blast holes,blasting methods and parameters,and blasting networks should be optimized and adjusted according to geological conditions and tunnel types.A combination of pre splitting and smooth blasting should be used,and blasting spatter should be strictly controlled;(4)Blasting disturbance is effectively controlled through construction blasting control and vibration monitoring,the site blasting condition is good and the calculation of different types of tunnel blasting vibration velocity symbol requirements verify the accuracy of the blasting scheme.
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