复合墩台局部冲刷试验研究

Experimental study on local scour around composite pier abutments

局部冲刷一直是冲积性河流中墩台失稳和水毁的主要原因,也一直是跨河工程可研与设计中需重点研究的问题。目前研究主要集中在单个墩台方面,对大型跨河工程复合墩台的局部冲刷研究较少。以长江苏通500kV过江电缆工程复合墩台为例,采用正态概化模型研究了复合墩台局部冲刷坑形态、范围及深度,阐明了局部冲刷的影响因素和规律。试验表明:大水深工况有利于复合墩台形成更大的局部冲刷坑,局部冲刷坑的相对长度、相对宽度和相对最大深度均与相对行近流速呈正相关关系。单墩比复合墩台相对冲刷深度要大,复合墩台相对最大冲刷深度与单墩相对最大冲刷深度的比值随相对行近流速增大而增大,范围在0.05~0.20。研究成果可为解决跨江大桥或电缆通道建设中的墩台局部冲刷问题提供参考。

Local scouring has always been the main cause for the instability and water damage of pier abutments in alluvial rivers,and it has also been a key issue in the feasibility study and design of river-crossing projects.At present,the research mainly focuses on a single pier abutment,and there is little research on local scouring of composite pier abutments in large-scale river-crossing projects.Taking composite pier abutments of Sutong 500 kV cable project in Changjiang River as an example,the shape,range and depth of local scouring pit around composite pier abutments were studied by using normal generalized model,and the influencing factors and laws were clarified.The results show that the large water depth condition is conducive to the formation of larger local scouring pits on the composite pier abutments.The relative length,relative width and relative maximum depth of local scouring pits are positively correlated with the relative approach flow velocity.The relative scour depth of the single pier is larger than that of the composite pier abutment.The ratio of the relative maximum scour depth of the composite pier to that of the single pier increases with the increase of the relative approach velocity,ranging from 0.05 to 0.20.The research results can provide a reference for solving the local scouring problem of pier abutments in the construction of river-crossing bridges or cable passages.