摘要
群桩基础广泛应用于海岸和海洋工程结构物中,波浪对群桩基础的冲刷有着重要影响。利用开源计算流体动力学程序REEF3D建立了三维数值波浪水槽,水槽入口和出口分别采用主动吸收方法和松弛法避免反射波影响。对非线性波浪作用下2×4群桩周围的局部冲刷进行了数值模拟,计算模拟出了下降流、马蹄涡、尾涡和间隙流等引起群桩局部冲刷的主要水流结构。计算结果表明,波浪中水质点垂向速度的变化会引起下降流和马蹄涡强度的变化。在研究的KC数范围(14.28~63.96)内,下降流和马蹄涡均较弱,不是冲刷的主导因素。KC较小时,冲刷主要受间隙流控制,最大冲深发生在上游第1排左右两行桩之间的区域,随着KC数的增大,尾涡逐渐成为主导冲刷的动力因素,发生最大冲深的位置逐渐转移至第1排桩的两侧。达到平衡时的最大无量纲冲刷深度随KC数的变化规律与单桩情形相似,群桩中各排桩周围最大冲刷深度的变化规律与波浪的非线性程度有关,非线性程度较弱时最上游和最下游两排桩的冲刷强于中间各排桩的,非线性程度较强时1个周期内正向水流的主导作用增强,由于前排桩的遮蔽效应,后排桩的冲刷深度减小。
Pile group foundations are widely used in coastal and marine engineering structures,and waves significantly affect the local scouring on pile group foundations.This article used the open-source computational fluid dynamics program REEF3D to establish a three-dimensional numerical wave tank.The inlet and outlet of the tank adopted the active absorption method and relaxation method separately to avoid the influence of reflected waves.Numerical simulations were conducted on the local scouring around a 2×4 pile group under nonlinear wave action,and the main water flow structures causing local scouring on the pile group,such as descending flow,horseshoe vortex,wake vortex,and gap flow,were calculated and simulated.The calculation results indicate that changes in the vertical velocity of water quality points in waves can cause variations in the descending flow and horseshoe vortex intensity.Within the KC number range(14.28-63.96)studied in this article,both the descending flow and the horseshoe vortex are weak and not the dominant factors of scouring.When the KC is small,the scouring is mainly controlled by the gap flow,and the maximum scouring depth occurs in the area between the left and right sides of the first row of piles in the upstream area.As the KC number increases,the wake gradually becomes the dominant driving factor for scouring,and the location of the maximum scouring depth gradually shifts to both sides of the first row of piles.The variation law of the maximum dimensionless scouring depth with KC number when reaching equilibrium is similar to that of a single pile.The variation law of the maximum scouring depth around each row of piles in a pile group is related to the nonlinearity of the waves.When the nonlinearity is weak,the scouring on the two rows of piles in the upstream and downstream areas is stronger than that of the piles in the middle.When the nonlinearity is strong,the dominant effect of forward water flow in one cycle is enhanced.Due to the shielding effect of the front piles,the scouring depth of the rear piles decreases.
作者
周熙
李小超
巩梦梦
ZHOU Xi;LI Xiaochao;GONG Mengmeng(School of Hydraulic and Ocean Engineering,Changsha University of Science&Technology,Changsha 410114,China;Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province,Changsha 410114,China;Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province,Changsha 410114,China;Engineering and Technical Center of Hunan Provincial Environmental Protection for River-Lake Dredging Pollution Control,Changsha 410114,China)
出处
《人民珠江》
2025年第5期108-120,共13页
Pearl River
基金
国家自然科学基金项目(51309038)。
