基于无人机倾斜摄影三维实景建模技术的特大桥桥台选址研究

西部山区修建高等级公路,为跨越深切峡谷地形,需要修建大跨径特殊结构桥梁。深切峡谷区地形、地质条件极为复杂,是崩塌、滑坡等频发的区域。某特大桥位于贵州省与四川省交界处,主跨为575.5 m的独塔双索面钢主梁斜拉桥,贵州岸(0号)桥台位于陡崖边缘,其稳定性是桥型方案是否成立的控制性因素,而桥台与陡崖的平面、空间位置关系对于桥基岸坡稳定性评价至关重要。受陡崖地形条件限制,地形图精度较差,地质调查工作受限,常规的断面测量工作无法获取高精度的地形数据。而应用无人机倾斜摄影技术,建立0号桥台前缘陡崖三维实景模型,为0号桥台选址研究提供了高清的影像资料和高精度的地形数据。基于三维实景模型与高精度地形数据,采用工程地质分析、有限元和离散元数值计算等方法,进行岸坡稳定性综合分析,为0号桥台的选址和优化提供了重要的理论依据。

Research on Location of Abutment for Extra-large Bridge Based on 3D Real Scene Modeling Technology of UAV Tilt Photography

The construction of high-grade highways in the western mountainous areas requires large-span bridges to cross the deep canyons.The complicated terrain and geological conditions of the deep canyons result in frequent collapses and landslides.A grand cable-stayed bridge,with a main span of 575.5 m,a single tower,double cable surface and steel main girder,is located in the boundary between Guizhou Province and Sichuan Province.The abutment in Guizhou side(0#)is located at the edge of the cliff.Its stability is considerable for the bridge designation.The relationship between the planes(abutment and the steep cliff)and spatial position is crucial for the stability.Due to the limited terrain conditions of the cliffs,it is difficult to develop geological survey and obtain accurate topographic map.But the conventional section survey cannot acquire the high-precision topographic data.Hence,it is very difficult for stability evaluation and site selection.However,the unmanned aerial vehicle(UAV)tilt photography provides high-definition image data and high-precision terrain data for the 0#abutment site selection study by establishing a 3D real-time model.The engineering geological analysis,finite element and discrete element numerical calculation provide an important theoretical basis.