汕头大学学报（自然科学版）

风场参数是桥梁抗风设计的基本参数，是某大跨独塔部分地锚式斜拉桥抗风风洞试验的前提.山区不同桥梁桥址地形地貌不同，研究获得的风场特性和规范规定均无法提供实际桥梁抗风需要的风场参数.新洲特大桥桥址处三河交汇，山势陡峻，为Y形深切沟谷库区，地形地貌极其复杂.本文首先通过地图获取主桥跨中为中心3 km（桥轴方向）×6 km（桥轴法线）范围的地形高程数据，借助Matlab和Autocad获得区域内离散点的高程数据，再通过Gambit软件生成桥址地形曲面.形成了以地形曲面为底面、高约1.5 km的矩形计算域，通过网格划分，采用大涡模拟（LES）计算了横桥向和顺桥向4个来流风向下桥梁周围横桥向和顺桥向的风场特征.研究表明，当风顺桥向吹，或从上游横桥向吹，在垂直桥轴线的主跨跨中1 000 m范围，风速基本均匀稳定，可取规范B类场地；但当风从下游横桥向吹往上游，受地形峡谷风效应的影响，风速剖面与规范B类风速剖面差别较大，特别是200 m以下.在桥跨位置300 m高度以下，不同位置的风剖面有差别，下游吹向上游时差别更为明显，这主要受桥址Y形深切沟谷对流动的影响和地面边界层效应.研究认为，如开展全桥模型风洞试验，宜在试验段布设地形缩尺模型，以合理模拟不同风向下，桥址风速场沿桥跨方向的不均匀性.

Wind field parameters are basic data for wind resistance design of bridges, which is the paramount condition of wind resistance in wind tunnel testing of a long-span single-tower partially ground-anchored cablestayed bridge. The topography and geomorphology of different bridge sites in mountainous areas are different, and the available wind field characteristics and code specifications can not provide wind field parameters required by actual bridge against wind. Xinzhou Bridge is located at the intersection of three rivers, characterized by steep mountains, Y-shaped deep valleys and reservoir area, which is extremely complex topography. In this paper, the terrain elevation data in the area of 3 km(bridge axis direction)×6 km(normal to bridge axis)centered at the bridge main span center are firstly obtained by GIS, and the elevation data of discrete points in the region are obtained with the help of Matlab and Autocad, and then the topographic surface of the bridge site is generated by Gambit software. A rectangular calculation domain with the bottom surface of the terrain surface and a height of about 1.5 km is formed. After meshing the computational domain, the Reynolds time-averaged Navier-Stokes(N-S)equation and the standard turbulence model are used to simulate the wind field characteristics of the bridge around the bridge site in four wind directions. The study shows that when the wind blows along the bridge or from the upstream side, in the range of 1 000 m at the main span center normal to bridge axis, the wind speed is basically uniform without notable difference, and the code-specified type B wind profile can be used, but when the wind blows from the downstream side, due to the influence of the terrain canyon, the wind speed profile is quite different from the code-specified wind speed profile, especially below 200 m. In addition, below 300 m, the wind profiles at different positions are different, and the difference is more obvious when blowing from downstream side, which is mainly due to the combined influence of the Y-shaped deep valley and the surface boundary layer. The study shows if the full bridge model test is carried out in the wind tunnel, it is suggested to set up a terrain scale model in the test section, as to reasonably simulate the non-uniformity of the wind field along the bridge span under different wind directions.