Research on Vibration Reduction Measures of Double Arch-tunnel Without Middle Drift
Based on the multi-arch tunnel of Menglu Expressway in Yunnan,a numerical model was es-tablished.The influences of the maximum single-segment explosive charge,inter-segment delay,ar-rangement of vibration-damping materials and thickness of vibration-damping rock column on sur-rounding rock damage,vibration velocity of previous tunnel and lining displacement were analyzed,and the suggested parameters were put forward in combination with the actual situation on site.The results show that:(1)It is suggested that the blasting method of step-by-step sequence should be a-dopted in the subsequent tunnel blasting excavation,and the maximum single-stage charge should be controlled within 15 kg.(2)In order to eliminate the influence of the error of detonator initiation time,the difference of blasting equipment performance and blasting technology,it is suggested that the interval delay be 100 ms.(3)Arranging the damping layer between the initial steel arch and the initial sprayed concrete can significantly reduce the vibration speed and displacement of the lining,so it is suggested to arrange the damping layer in this way when the site construction is feasible.(4)With the increase of the thickness of the isolation rock column,the deformation of the first tunnel support gradually decreases.The lining speed first decreases and then increases,and reaches the mini-mum value when the thickness of rock column is 1.5 m.It is suggested that the thickness of vibration isolation rock column should be 1.5 m.The research process and results can provide guidance and suggestions for the field construction of similar projects.
double arch-tunnel without middle driftmaximum charge amount in one time delayinter-val of delay blastingvibration damping layeranti-vibration rock pillar
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维普
