Flow Friction Of Pile And Pile Group And Its Application On The Tidal Numenical Modelling

Piled wharf (wharf with pile group underwater structure) is a kind of structure, which is very commonly used in port engineering. The flow pattern in the region of pile group is complicate, and is still rarely to be studied at present. Usually, in a real project, the flow pattern in front of the piled wharf is studied by means of physical model test or numerical simulation. Because the water area to be studied in such project is generally so large that an abnormal model should be used in the physical model test and also there is no suitable numerical model for such kind of structure in numerical simulation up to now. In order to preview the variations of flow pattern in the water region after construction, the piled wharf is usually simplified as a vertical quay in these two kinds of models at present. Making such simplification can not reflect the effects of pile group on water flow completely and so can not describe the real flow pattern in front of the piled wharf either.The flow resistance of pile group is more complicated than that of single pile. It is difficulty to solve flow resistance of pile group theoretically at present. A set of physical model tests were made here and a calculation method considering resistance coefficient of pile group was applied in the numerical simulation of piled wharf through analysis and research. In the governing equation of numerical simulation, factors of resistance considering effects of pile or pile group were applied.Three parts of research work are included in this paper. They are a set of physical model tests, numerical simulation and project application.1. Three physical model experiments:(1) The tests of the resistance of single pile and group pile in water flume: different shape of pile section with different array style were adopted in the experiment;(2) Model tests of pile group resistance in water flow in a water basin ;(3) Model tests for a piled wharf in a wide water flume.The resistance coefficients with different shape section and different array style have been obtained through above-mentioned three physical model experiments and have been applied in numerical simulation as well.2. Numerical simulation:The fundamental governing equation of two-dimensional tidal flow under the influence of pile body has been induced through theoretical analysis, and a numerical flow flume for simulation has been built as well. Within the numerical simulation flume, the pile group has been replaced by the additional roughness coefficient obtained from the physical model tests in pile foundation region, and the water depth has been revised according to the principle for equality of flow section as well. Then the variation of flow velocity for flood and ebb tide flow in the water region of the wharf frontage and vessel turning basin has been obtained. The obtained results are quite coincident with the results of the equivalent physical model tests. It proves that using the method of additional resistance coefficients and revised water depth can simulate the effects on water flow by pile group quite well.3. Project application:Depending on the above research results, the numerical simulation method for two dimensional water flow has been applied in calculating the five piled wharf berths of the first phase project of Yangshan port of Shanghai international shipping center. Among the simulation system, the above mentioned research results have been used to simulate the effects on the water flow by piled wharf, which makes the result more tallies with the actual situation. The results have been applied in the project design and research.