Investigation Of The Influence Of Mountain Canyon Configurations On Canyon Wind Characteristics

The wind field characteristics of the mountainous canyon terrain is one of the important factors considered in the wind resistance design of the bridge.Especially in the mountainous areas of western China,the complex and diverse canyon forms lead to the complexity and difference of wind field characteristics.Parameters such as the width of the canyon and the slope of the mountain have a great influence on the wind field characteristics.However,The research and discussion about the wind characteristics of specific canyons at home and abroad are relatively insufficient,and the measuring data and related documents are also scarce.Therefore,it is necessary to conduct a comparative study on the wind field characteristics of different canyon forms to provide a basis for the subsequent numerical simulation and engineering practice of similar canyon wind characteristics.This paper takes the wind field characteristics of mountainous terrain as the research object and abstracts the canyon into a U-shaped valley by changing the width of the canyon model and the slope of the mountain.The wind field characteristics and The change law inside the canyon were compared and analyzed through wind tunnel tested.This paper summarizes the different canyon forms impact on its internal wind field.Main research content:(1)According to the Irving formula,the simulation design of the atmospheric boundary layer was carried out,including the size of the wedge,the roughness element and the layout spacing,and the boundary layer simulation layout of the D-type landform was obtained,and the flow field verification measurement was carried out.(2)Based on the terrain of the western mountainous area,a trapezoidal cross-section canyon model was designed.The canyon model was placed in the D-type landform,and different canyon forms were obtained by changing the slope of the mountain and the width of the canyon bottom.The change of the average wind speed and turbulence intensity at each measurement point under different canyon widths,different mountain slopes and different heights.At the same time,the influence of canyon width and canyon slope on canyon wind characteristics and wind field distribution were also studied.The main research results:(1)The wind speed and turbulence in the canyon are greatly affected by the width of the bottom of the canyon,the slope of the canyon and the direction of the incoming flow.When the direction of flow is 0°and 3°,the greater the width of the bottom of the canyon,the lower the wind speed at the same location,the greater the intensity of turbulence,and the more gentle wind speed changes caused by the canyon.When the direction of the flow is 7°and 9°,the greater the width of the bottom of the canyon,the greater the wind speed at the same location,the lower the intensity of turbulence,and the more gentle wind speed changes caused by the canyon.(2)When the direction of the incoming flow is 0°,3°,9°,the slope of the canyon is greater,that is,the steeper the mountain,the greater the wind speed,the lower the intensity of turbulence,and the direction of the flow is 7°,the greater the slope of the canyon,The greater the wind speed,the greater the intensity of turbulence.(3)The wind speed at the middle position at the same height is higher than the wind speed on both sides of the canyon,and the turbulence intensity at the middle position is lower than the turbulence intensity on both sides of the canyon.At the mid-span,at the same measuring point,when the incoming wind direction is 7°,the wind speed is the highest,and at the quarter-span the greater the wind direction angle,the lower the wind speed.