中文摘要：

针对砂土中沉井基础局部冲刷形态的体型影响效应开展波流水槽模型试验研究,并与中国、美国和新西兰规范的冲刷深度计算公式进行对比分析。试验设计了圆形和方形2种形状的沉井基础,在给定水深和流速条件下进行冲刷试验,重点考察了沉井基础的形状、尺寸和布置方式等体型因素的影响规律。研究结果表明：圆形沉井最大冲刷深度和冲刷范围分别位于迎水侧和背水侧的45°范围附近,其冲刷深度随着沉井直径增大而有所增大;根据圆形沉井周围冲刷形态的动态演变特征,可将其形成的局部冲刷形态分为清水冲刷区、动床冲刷区和冲刷沉积区3个典型区域;方形沉井的冲刷主要发生在方形角点的附近,在不同的角点位置,其冲刷程度有着明显的区别;与中国、美国以及新西兰规范的冲刷深度计算方法对比表明,这3种规范方法对于小直径沉井的计算结果与实测值均大致相当,但对于直径较大的沉井基础则都存在着显著的误差,需要进行适当的修正,以反映体型效应对于沉井局部冲刷深度的影响。

英文摘要：

Wave flume model tests on scale effects of local scour configurations around caissons embedded in sand were carried out.Meanwhile,calculation methods of scour depth in the codes of China,USA and New Zealand were compared and analyzed.Experiments of circular and square foundations,which focused on the effect laws of scale factors including dimensions and arrangements,were conducted in constant water depth and flow velocity.The results show that the maximum scour depth is observed around the upstream boundary（about 45°）,while maximum scour range is observed around the back of the caisson（about 45°）for the case of circular caisson.Furthermore,the scour depth increases with the increase of caisson diameter;the local scour modes can be divided into three typical areas according to the dynamic characteristics of scour mode evolution around circular caissons：clear-water area,live-bed area and deposition area;for the case of square caisson,scour happens mainly around the corners,and the scour extents show obvious differences according to corners＇positions;comparing thespecifications of China,USA and New Zealand for calculating the scour depth,it is suggested that the calculated results of these 3 methods are in agreement with the measured results for caissons with small diameter,while inaccuracies appear when they are used to calculate those with large diameter in which the methods require appropriate correction to better reflect scale effects on the local scour depth around caisson.