Vibration reduction effect of retaining pile structure under the action of damping hole-A case study

In the context of mitigating the impact of blasting-induced seismic waves on excavation processes and reducing the vibrational load on retaining pile structures, this study examines the influence of predetermined damping hole parameters on the damping effect. It also evaluates the protective efficacy of damping holes on retaining pile structures. Leveraging the foundation pit project at the Julong Avenue Station of Wuhan Metro Line 7 as a reference, on-site blasting construction was monitored to obtain vibration velocities at the top of the retaining pile structure. A numerical calculation model for blasting in the foundation pit was established using LS-DYNA software, and its reliability was verified through the integration of on-site monitoring data at the top of the retaining pile. Multiple damping hole excavation schemes were devised, and their effects on the damping effectiveness were analyzed with respect to various parameters. Safety criteria for the stability of the retaining pile structure were proposed based on the ultimate tensile stress criterion, ultimate shear stress criterion, and Mohr's criterion. Under the optimized scheme, the dynamic response characteristics of the retaining pile structure were analyzed, and the practical application effects on-site were observed. The research findings indicate that the depth, spacing, and number of damping holes have a significant impact on the damping effect. The safety criterion for the vibrational velocity of the retaining pile structure during blasting is determined to be 26.10 cm/s. Under the optimized scheme, the vibrational velocities at various monitoring points on the retaining pile structure all fall within the safe range, with a maximum reduction rate of 30.9%.