滑坡体积精确计算看似简单实则困难。黄土高原具有植被稀少、岩土暴露程度高、滑坡易发多发等特点。本文在充分认识上述特点的基础上,尝试采用高精度低空摄影测量技术来精确测算滑坡方量。与传统计算方法、遥感和三维激光扫描对比,低空摄影具有受各类因素影响较小、作业灵活、高效、产品精度高等优点。本文以甘肃黑方台党川2#黄土滑坡为例,在介绍近景摄影测量数据获取方法的基础上,采用滑坡前后的高精度的低空摄影测量数据源和结合现场调查,对该滑坡进行精细测绘,实现"数字化滑坡"。研究结果表明:(1)滑坡长217m,宽176m,滑坡平均厚度约20m(滑源区),滑距782m,后缘到前缘的落差122m,影响面积为105216m~2;(2)根据斜坡各部分滑动和堆积特征,将其细分为崩滑区、主滑区、滑塌区、流通堆积区、铲卷堆积区、挤压堆积区、二次堆积区、粉尘堆积区;(3)以高精度DEM求得,滑动和堆积方量体积分别为31.72×10~4m~3和49.96×10~4m~3;(4)滑坡整体松散系数为1.411,局部的干密度差别较大,其大小与滑坡发育特征和运动过程有密切关系。
The precise calculation of landslide volume seems simple but difficult actually. The Loess Plateau has a few characteristics which include sparse vegetation, high degree exposure of rock and soil, and landslide susceptibility. It has occurred many landslides. Compared with the traditional calculation method,such as remote sensing and 3D laser scanning,digital close-range photogrammetry is little affected by all kinds of factors and has the features of flexible operation,high efficiency and high precision products. This paper uses Dangchuan 2#loess landslide in Heifangtai tableland as an example. It uses high resolution close-range photogrammetry data to analyze topography change between pre-sliding and post-sliding. Based on the field investigation and carrying out fine mapping of the landslide, this paper realizes the digital landslide. The detailed study consists of landslide influence,landslide area,landslide volume,loose coefficient of landslide volume and the local dry density change.The results are shown the follows.( 1) It covers a total area of 105216m~2,with 217 m in north-south direction,and176 m in west-east direction. The average thickness of the landslide is about 20m( slip source area),with sliding782 m,trailing 122 m in altitude from the landslide crown to landslide top.( 2) According to the characteristics of the sliding and accumulation of each part of the slope,it is divided into the collapse zone,the main sliding zone,the sliding zone, the circulation accumulation area, the shovel winding accumulation area, the extrusion and accumulation area,the two accumulation area and the dust accumulation area.( 3) According to high resolution DEM,the sliding volume is 31. 72 × 10^4m3 and accumulating volume is 49. 96 × 10^4m3.( 4) The overall loose coefficient of the landslide is 1. 411. The local dry density has great difference,which has close relationship with the development characteristics and the movement process of the landslide.