Study Of The Wave Slamming Force On The Elevated Pile Cap For Seacrossing Bridges

As a key project and an important part of the “21st century maritime silk road”,the seacrossing bridge play an important role in China’s coastal traffic network,which is of great strategic significance.Different from the land bridge,the offshore bridge is in the complex and variable marine environment,which inevitably suffers from harsh wind and wave loads.The elevated pile cap is widely used as a form of foundation of sea-crossing bridges in China,the cap commonly locates in vicinity of sea level and directly subject to Typhoon-induced extreme wave impact loadings.Wave loading,as a key controlling effect for marine structures,pose a great challenge to design,construction and disaster prevention and mitigation of the elevated pile cap.On the basis of engineering background of the elevated pile cap of Pingtan Strait Rail-cum-Road Bridge,this thesis investigates the effects of wave slamming on the elevated pile cap of sea-crossing bridges by means of approaches including model test,numerical simulation and analytical derivation.The main research contents are listed as follows:(1)The research status and progress of wave loads calculation of the elevated pile cap are introduced by summarizing and classifying the investigation of the interaction between waves and structures.The deficiencies of the current research on the mathematical model of time history of wave slamming loads on the elevated pile cap are pointed out.(2)An experimental research program of wave impact on the elevated pile cap is put forward.The scale of the model is determined according to the gravitational similarity criterion.The variables of testing parameters,wave height and clearance,are determined,and an effective post-processing method for the data of wave force results is proposed.(3)The characteristics of time history of wave loads are discussed based on the testing results.The effects of underlying pile group,wave heights and clearances on the wave impact loads are investigated.(4)A three-dimensional numerical model of interaction between waves and elevated pile caps is established,and the refined CFD numerical simulation is carried out with some experimental scenarios been taking as examples,which validated the reliability and effectiveness of the numerical model.Furthermore,the flow field information during the interaction between waves and the cap model is given in detail,which demonstrates mechanism of the vary of wave loads on the cap model in some extent.(5)A simplified mathematical model of the time history of wave slamming loads on the cap is presented based on the statistical analysis of experimental results.The probabilistic model of horizontal wave impact force is proposed,which determines marginal distributions of wave impact maxima and rise times and their joint probability using Copula function.