FIELD MEASUREMENT STUDY ON WIND CHARACTERISTICS AT BRIDGE SITE IN DEEP GORGE WITH HIGH ALTITUDE

Using the long-term wind measured data of a wind observation tower at the bridge site of a long-span bridge over a deep gorge, the mean wind characteristics of the wind field were analyzed, taking 8 m/s as the wind speed lower limit of strong wind, and the fluctuating wind characteristics of strong wind samples were also investigated. The study results show that: the impact of topography on wind characteristics is significant in the deep gorge, the distribution of wind characteristics parameters is anisotropic, the wind directions of the maximum wind speed and extreme wind speed are concentrated near the gorge axis, predominant wind directions at all observation height are SSE, the most of the attack angles of strong wind are negative, and wind speed and wind attack angle are significantly correlated with wind direction. The vertical distribution regular of wind speed is different from that of an exponential law model, the wind profile index reduces with the increases of wind speed and is significantly correlated with wind direction, and the mean value of fitted wind profile index is 0.09. The turbulence intensities of longitudinal, of lateral and, of vertical are 0.17, 0.12 and 0.27, respectively. The vertical turbulence intensity is on the high side, and both the linear and nonlinear models can well fit the relationship between turbulence intensity and gust factor. The turbulence integral scale is higher than the standard recommended value and increases with the increases of wind speed. The agreement between measured power spectrum and theoretical spectrum is poor, vertical power spectrum is on the high side, and fluctuating wind speed power spectrum does not satisfy the isotropic hypothesis in inertial subregion.