Study On Influence Of Wind Barrier Upon Wind Environment On Bridge Floor By Numerical Simulation

Crosswind may cause traffic accidents such as vehicle sideslip and overtruning, especially when running on long-span bridges. The problems of wind induced traffic safety are becoming more serious due to the factors of the altitude of the bridge floor above the see level and flow over structures. There are many reports of crosswind induced accidents which may cause heavy traffic jams. The problems of traffic safety under crosswind are receiving increasing concerning. Wind barrier is a main method to assure traffic safety, especially under strong crosswind.Computational Fluid Dynamics is a new subject originated from about 40 years ago, which have been applied in lots of regions in over 10 years. In this thesis, on the basis of CFD theories, relying on strong model-building and analysis platform of FLUENT, numerical simulation is carried out to investigate the influence of wind barrier on wind enviroment above the bridge floor. Firstly numerical simulations of the wind environment on the bridge floor under crosswind without wind barrier, with full wind barrier and with local wind barrier are performed to analyse the effects of the wind barrier on the wind environment on the bridge floor. Then the critical wind speeds of safety driving concerning four typical vehicles are calculated considering wind speeds, vehicle dimensions, road surface conditions and vehicle speeds and analysis of effects of the full wind barrier and local wind barrier on traffic safety of various vehicles are performed. Finally 3D models of trains under crosswind with and without wind barrier are built base on the accident of train overturning in Sinkiang. From the calculation results of 3D turbulence flow over trains, pressure distribution, path lines and aerodynamic forces of model trains are analyzed and obtained. Then the derailing coefficient and rolling coefficient which are used to evaluate the stability of trains under crosswind are derived and the effects of the wind barrier on traffic safety of trains are discussed. The research achievements in this thesis must have important referential significance and practical values to assure traffic safety.