郑焦铁路黄河大桥桥墩局部冲刷试验研究

为了保证郑焦铁路黄河大桥桥梁基础安全,同时尽量避免桥梁基础因设计偏于安全而造成工程投资的增加,按单宽流量、河势以及桥墩防护的多种组合,开展了桥墩基础局部冲刷试验研究,分析了桥墩局部冲刷的水流现象、冲刷坑形态和冲刷深度。结果表明:局部冲刷最深点在承台下的桩群之间,略偏向桥轴线上游部位;墩后形成带状淤积体,淤积体随单宽流量的增大而增大。水流方向与桥轴线正交时,桥墩周围的局部冲刷坑形态基本沿桥墩轴线对称分布;水流方向与桥轴线法线存在夹角时,冲坑范围扩大、冲坑深度明显增深,桥墩两侧马蹄形旋涡不再对称分布。墩前抛石护底后,局部冲刷坑深度明显变浅。

Experimental Study on Local Scour of the Yellow River Bridge Pier of Zheng - Jiao Railway

In order to guarantee the safety of the Yellow River Bridge of Zheng-Jiao Railway and at the same time avoid investment increase caused by design emphasizing safety,according to unit discharge,river regime and pier protection,experiment study on pier local scour was carried out.The paper analyzed flow phenomenon,shape and depth of local scour.The results indicate that the deepest point is among pile group under caps and upstream bridge axis.There is strap deposition behind the pier.With the increase of unit discharge,the strap deposition increases.When the direction of flow is orthogonal with pier,local scour shape is nearly symmetric distribution along the bridge pier axis.When there is an angle between flow direction and bridge axis normal line,scour range and depth obviously increase and local scour shape is not symmetric distribution.When stones are thrown at the front of pier to protect bed,local scour depth evidently decreases.Analysis on pier local scour and remedial measures can offers technical supports for the formation bridge design report.