基于无人机摄影测量的露天矿边坡数值模拟

Numerical simulation of open-pit mine slope based on unmanned aerial vehicle photogrammetry

数值模拟是露天矿山边坡稳定性分析的常用方法,边坡模型构建是数值模拟的基础,地形测量的准确性对于边坡稳定性分析精度具有十分重要的影响。近年来,低空低速小型无人机(UAV)被广泛应用于地质调查中,为复杂条件下地形快速测量提供了一种可行的方法。针对露天矿山边坡坡形更新快、地形复杂、人工测量困难的情况,采用搭载单镜头小型无人机,对露天矿山边坡进行低空摄影测量,并通过飞行试验,对比研究了无人机搭载镜头旋转角度对边坡测量精度的影响,最终得到高精度边坡数字高程模型(DEM),并通过Surfer、Rhino等软件转化为三维FLAC模型,实现从无人机测量到三维数值模型的快速建立。得到以下可供参考的研究结论:在目标边坡坡度小于45°时,无人机搭载镜头旋转角度不同对边坡测量精度有较大影响,当镜头旋转角度介于70°~90°时,获得的测量精度较高;与人工测量相比,无人机摄影测量获得的边坡坡形更符合真实边坡实际坡型;无人机航拍照片经过PhotoScan、Surfer、Rhino等软件的转化,能够快速建立三维数值模型,并获得更好的数值模拟计算结果,满足边坡稳定性分析需要。

Numerical simulation is a normal method for slope stability analysis in open-pit mines. Slope model construction is the basis of numerical simulation, and the accuracy of topographic measurement data has an important influence on the accuracy of slope stability analysis. In recent years, low-altitude and low-speed small unmanned aerial vehicles(UAVs) have been widely used in geological surveys, which provide a feasible method for rapid terrain measurement under complex conditions. Considering the situation of the rapid change of slope shape of the open-pit mine, the complex terrain, and the difficulty of manual measurement, a single-lens small unmanned aerial vehicle(UAV) was used to perform low-altitude photogrammetry on an open-pit mine slope. Through UAV flight tests, the influence of the rotation angle of the UVA mounted lens on the slope measurement accuracy was compared and studied. Finally, a high-precision slope digital elevation model(DEM) was obtained, which was converted into a three-dimensional FLAC3D model using several softwares such as Surfer and Rhino. A rapid establishment was realized from the UAV measurement to the 3 D numerical model. The following research conclusions can be obtained for reference: when the target slope is less than 45°, the rotation angle of UAV mounted lens has a large influence on the slope measurement accuracy. When the lens rotation angle is between 70° and 90°, relatively higher measurement accuracy can be obtained. Compared with manual measurement, the slope shape obtained by the UAV photogrammetry is more in line with the actual slope shape. After a series transformation of the aerial photos of UAV using the PhotoScan, Surfer, Rhino, etc., a 3 D numerical model can be quickly built, and better numerical simulation results can be obtain to meet the needs of slope stability analysis.