Study On Drag Force Characteristics Of Cylinder Piles And Influence On Scour-Deposit Of Bottom Sediment

Cylinder pile cluster foundation is extensively used in wharfs, bridges and oceanicplatform projects. Studies on drag force characteristics of cylinder pile cluster anderosion-disposition influence imposed on flow and bottom bed are of importance and alsothe key to successfully simulate pile cluster.The dissertation aims at the shortage of data on drag force characteristics of cylinder pilecluster in uniform flow with free surface and limited water depth, and carries on flume testson cylinder pile cluster drag force and acquires drag force characteristics of cylinder pile;tests drag force of pile cluster with various arranging formats and up-flow angles, recognizeslaw of up-flow angles influencing drag force of pile cluster, finds empirical formula ofcalculating pile cluster drag force coefficient ko from horizontal influencing coefficient k_H,vertical flow-covering coefficient and up-flow angle, puts forward calculating method andformats about drag force of pile cluster, effectiveness and precision of which is verified bytest data, and supplies theoretical base for precisely computing drag force in projects.Local erosion-deposition of bottom bed near pile cluster is also a factor that must beconsidered in simulating pile cluster. Therefore, the dissertation makes comparative tests oflocal erosion-deposition among different pile clusters in the same flow, and among the samepile cluster in different flows, and acquires local erosion-deposition laws of pile cluster nearbottom bed. It is found that arranging format of pile cluster has much influence on localerosion-deposition near bottom bed, and that some difference exits between localerosion-deposition characteristics at bottom bed near pile cluster in different flows.Arranging format of pile cluster has much influence on characteristics of drag force andlocal erosion-deposition near bottom bed. It is necessary for successfully simulating pilecluster to consider as much as possible arranging of pile cluster while drag force similarity issatisfied.