Velocity and stress response and damage mechanism of three types pipelines subjected to highway tunnel blasting vibration

•Velocity and stress responses of pipelines under tunnel blasting was investigated.•Increase of stress of pipeline was much greater than that of velocity.•The position of maximum velocity was not exactly accord with that of maximum stress. The safety of water pipelines subjected to tunnel blasting with a short distance are becoming a difficult and urgent problem to be solved in tunnel construction. It is necessary to investigate the velocity and stress response of water pipelines caused by tunnel blasting excavation. Three-dimensional numerical models of the tunnel, stratum, and circular, square and horseshoe-shaped pipelines were established using ALE algorithm with ANSYS/LS-DYNA software. Blasting vibration was tested simultaneously on the ground surface to verify the reliability of the numerical model. The effects of clear distances, initiation charges, and properties of soil around pipeline on velocity and tensile stress of circular, square and horseshoe-shaped pipelines were analyzed, respectively. The results showed that the relative errors of the peak vibration velocity on the ground surface between the measured values of the field test and the analyzed values of the numerical model were less than 5%. The peak velocity and tensile stress of three types pipeline increases as the charge of cut holes increases and the clear distance decreases. The peak values of vibration velocity and tensile stress on the circular pipeline were the highest, next was the square pipeline, and the last was the horseshoe-shaped pipelines. Besides, the increase of stress was much greater than that of velocity. The tensile stress increased by 6 to 8 times larger than before, but the velocity is only increase by 2 to 3 times. The occurrence position of the maximum velocity was not exactly consistent with the position of the maximum stress of the pipelines. When the underground pipeline is surrounded by pebble sand, the peak vibration velocity and peak tensile stress of the pipeline are the largest, while those of backfilling clay and rammed sand are smaller.