Journal of North China University of Water Resources and Electric Power(Natural Science Edition)

【Objective】 The study reveals the influence mechanisms of three pile group arrangements-no piles, plum blossom-shaped, and rectangular-on the array effects of breach flow fields and their hydrodynamic characteristics, aiming to provide a theoretical basis for optimizing pile group layouts in dike breach emergency response. 【Methods】 A three-dimensional dike breach model was established using FLOW-3D software to simulate the evolution of breach flow patterns under the three pile group arrangements. The influence of pile groups on breach hydrodynamics was systematically evaluated. 【Results】(1) Pile group arrangements significantly reduced flow velocities in the breach and floodplain areas while optimizing flow field distribution.(2) Compared to the no-pile condition, pile group arrangements decreased the maximum breach flow velocity from 2.305 m/s to 2.094-2.185 m/s, resulting in reductions of approximately 5.21%-9.15%. The mainstream velocity in the floodplain area decreased from 2.880 m/s to 2.182-2.840 m/s, resulting in reductions of approximately 1.39%-24.24%.(3) The water depth distribution pattern in the breach zone under the three layouts was as follows: in the no-pile and plum blossom-shaped layouts, water depth at the breach gradually decreased along the flow direction; in the rectangular arrangement, water depth at the breach was higher at the front and rear sides and lower in the center, forming a triangular high-water-depth zone in the downstream floodplain.(4) The rectangular arrangement demonstrated the most effective flow attenuation, followed by the plum blossom-shaped arrangement, whose velocity variation pattern resembled that of the no-pile arrangement. The flow pattern at the breach under the plum blossom-shaped arrangement was smoother than that under the no-pile arrangement. The rectangular arrangement proved superior in mitigating hydraulic forces and improving breach flow patterns. Its triangular high-water-depth zone effectively reduced flow impact, enhancing protection of downstream floodplain areas. 【Conclusion】 The hydrodynamic regulation advantages of different pile group layouts vary, with the rectangular arrangement demonstrating the most comprehensive effectiveness in flow velocity reduction and flow pattern improvement. This study provides a scientific basis for optimizing pile group design in rapid breach closure projects, holding significant practical insights for enhancing emergency response efficiency and flood disaster management capabilities.