Mountain Valley Bridge Site Wind Characteristics Field Measurement Study And Numerical Simulation

With the gradual implementation of the strategy of western development, in the Midwest region more and more flexible long-span bridge over mountain valley will be constructed, In order to ensure the successful construction of such bridges and normal operations,accurate wind load input is a prerequisite for flexible large-span bridge wind design. However, the mountainous valley area terrain is rather complex, the wind field characteristics is difficult to determine,and existing bridge wind-resistant specification don’t have detailed description about parameters of canyon terrain. So, the study of the mountain canyon wind field characteristics has important significance.Relying on west traffic issues major projects "large bridge monitoring of wind and rain and study of Simulation Technology". The following research on wind field characteristics at the bridge site of Lishui Bridge were conducted.1. Established a mountainous valley wind environment real-time monitoring system at Lishui Bridge site, valley wind characteristics on the bridge site were real time monitored, and digital recorded on hard disk truly and valid record, enormous amount of data were analyzed to get the valley wind average wind characteristics including of the average wind speed,wind direction,wind speed profile,wind attack angle and the fluctuating wind characteristics including of turbulence intensity, gust factor, turbulence power spectral density etc. And the correlation between the characteristics of parameters were also analyzed. Lishui Bridge site wind field affected by the mountainous valley terrain, the three-dimensional characteristics is very complex. Research results exhibit that:Since Lishui Bridge Canyon is curved, the main stream wind did not occur flow through to form significantly valley effect; distribution of wind attack angle range between -9°and+7°, fluctuation is larger; turbulence intensity close to specification Class D the earth surface requirements value.2. Using numerical simulation techniques in conjunction with reverse engineering software, established a large-scale real valley terrain CFD mode at the bridge site, use CFD numerical simulation to research the wind field characteristics of valley topography at the bridge site. Study get a complete the real terrain numerical simulation technology roadmap and reasonable entrance boundary conditions, also get single exponential rate wind profile does not meet canyon terrain wind speed variation with height conclusions etc, in contrast with the field test results.3. In order to obtain the universal significance distribution law of valley wind field characteristics,established a series simple numerical valley model,relationship between the wind field characteristic and valley width as well as relationship between the wind field characteristic slope was analyzed, and made a fitting formula,can be used as reference of define as such terrain bridge site wind parameters.This paper mainly through field measurement and numerical simulation two research methods, Lishui Bridge located on the mountain valley wind field characteristics were studied. Results not only for the normal operation of Lishui Bridge played a very good role and also provides a reference in guiding the work of the follow-up study of mountain wind environment.