Study On Strong Wind Characteristics Of Typical Complex Terrain Bridge Site In Mountain Area

The study of the wind field characteristics in the bridge area is the most basic subject in the bridge wind engineering.At present,the research on the wind field characteristics of the mountain canyon is not sufficient,and the current wind resistance specification only gives the corresponding provisions of the flat land surface wind field characteristic parameters.It is unable to meet the requirements of complex and variable wind field characteristics of mountainous canyons.For the wind-resistant design of mountainous bridges,special research on the wind field characteristics of such typical mountainous terrains must be carried out.In this paper,the typical complex terrain(trumpet terrain)in the western mountainous area is taken as the research object.Using ANSYS FLUENT,three turbulence models are selected to simulate the strong wind characteristics of the terrain model bridge,and the wind tunnel test results of this research group are compared and analyzed to verify the nulmerical value.The feasibility and accuracy of wind tunnel research on complex terrain bridge wind fielrd,and choose the appropriate turbulence model.On this basis,the multi-topographic parameters of the trumpet terrain wind field(changing the angle between hills on both sides of the can,yon,the angle of trumpet mouth entrance,etc.)are simulated,and the distribution mechanism of the typical topographic flow field and the variation law of the wind field are given.The function law of the variation of the downcdraft parameters of various shape parameters is proposed.Firstly,the numerical simulation of wind characteristics is carried out for the typical complex terrain in the actual mountainous area.The difference between the basic wind characteristic parameters and the general wind characteristic parameters of the mountain bridge area is obtained,and several types of terrain parameters that have a greater influence on the bridge wind field are identified.The turbulence model is more suitable for canyon terrain calculation.Secondly,by numerical simulation of wind characteristics of different canyon angles and different bell mouth entrance angles,the transformation law of wind field in canyon with terrain parameters is obtained.The variation range of the gradient wind height is given,and the curve of the wind speed with the length and vertical height of the canyon is plotted.It shows the change of the wind field flowing into the canyon through the canyon mouth and fits the wind speed.The function model of the angle between the angle of the canyon and the entrance of the bell mouth is introduced.Finally,the real bridge model is introduced into the simplified canyon terrain,and the influence degree of the wind field in the canyon before and after the actual bridge is explored.The wind speed is obtained in the horizontal direction and the vertical direction respectively.The range of increase in wind speed and the maximum wind speed difference were calculated from the range affected by the bridge.The overall research results can provide a basic reference for the wind-resistant design of bridges under similar terrain.