Shaking Table Test on Borehole Stability of Bridge Pile Foundation under Blasting Vibration
This study focuses on the impact of nearby blasting vibration on the stability of completed boreholes of the bridge pile foundation.Based on a cable-stayed bridge that has a main span of 280 m and was constructed alongside the nearby mountain blasting project,a soil box model and a 1:40 borehole model were designed and prepared for shake table tests,to analyze the failure characteristics of the borehole walls,soil vibration velocity and the dynamic soil pressure.As per the tests,both the peak soil vibration velocity and dynamic soil pressure grew bigger as the blasting impact was gradually intensified,once the soil was damaged,the peak soil vibration velocity and dynamic soil pressure showed the sign of non-linear increase.The variation of peak soil pressure exhibited a"U"trace when the blasting intensity was small,while a"W"trace when the blasting intensity was big,which was concentrated at the central and upper parts of the boreholes.The mountain blasting vibration can result in the damage of the central and upper parts of the borehole below the interface of the bottom of steel casings and soil.The mountain blasting construction must be monitored,peak vibration velocities of the nearby boreholes should not exceed 2 cm/s,so as to ensure the borehole stability.
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