波浪作用下跨海桥梁桩基冲刷防护装置特性研究

Properties of Novel Local Scour Protective Equipment around Pile of Bridge under Wave Action

跨海桥梁结构的稳定性受到桩的冲刷作用影响。本文发展了一种近海环境下降低桩周局部冲刷作用的防护装置,装置由一个上部护圈和一个筒身钻有纵横排列的孔洞的护筒构成。基于相似模型试验理论,在波浪水槽中开展了单桩系列冲刷模型试验,研究了防护装置的特性。波浪水槽设置了长17m,宽1.4 m,深1.0 m的试验段,一个长4.8m深0.5 m的砂槽置于水槽的中部。试验系统由浪高仪和冲刷深度内窥镜测试装置形成,通过造波机造波进行试验测试,试验中对单桩和串列双桩在无防护和有防护下局部冲刷特性进行了研究。结果表明,桩周最大冲刷深度与波高、波长和桩径成正比,而与水深和护圈直径成反比关系,前后桩之间有相互影响。本装置可以有效降低由波浪引起的桩周局部冲刷作用,且存在一个适中的防护筒高度,超过这一高度,防护效果明显降低。

The stability of marine bridge structures affected by scour around piles.In the present paper,novel protective equipment is developed to reduce local scour around bridge piles under coastal environment.The equipment is composed by a collar at the top and a protective tube with rows and columns circle holes at the surface of tube.Series of wave flume model tests are performed on single pile to study the properties of the new equipment based on the principal of similarity.Wave flume experiments are carried out in a wave flume with a test section of 1.4 m wide,1.0 m deep and 17 m long and a 4.8m long and 0.50m deep sand bed section is installed in the middle of the wave flume.The test system is comprised with wave monitors and an endoscope detector for scour depth.Series of wave flume experiments are performed under regular waves generated by the wave maker.Properties of local scour around the single pile and the two-piles in tandem arrangement with or without the protective equipment are compared by means of experimental method.As a result,the maximum erosion depth around the pile is in direct proportion to the wave height,wave length,and pile diam-eter, but in inverse proportion to water depth and collar diameter. And there is interaction between the formerpile and the rear pile for the two-piles in tandem arrangement. It is concluded that the protective equipmentpresent here can reduce the depth of local scour at the pile effectively on basis of the experimental results. Amoderate height of protective device is benefit for reduction of scour.