检查大坝是否可持续水力发电

Author: Anne Pitkaenen

When you approach Lai da Nalps, a reservoir in the municipality of Tujetsch, Grisons, Switzerland, the massive dam structure of 127 metres height and 480 metres width opens majestically already from the distance. The large arch dam is built for hydroelectric power generation at almost 2,000 m above the sea level. Hydropower is considered the backbone of today’s high security of electricity supply in Switzerland.

Lai Da Nalps is located close to the Gotthard tunnel, this and other dams nearby are monitored automatically for acute movements and changes. In addition to the detailed monitoring, an inspection of the dam construction is done visually to document the condition for long-term understanding of the dam’s health.

大坝由瑞士水力发电的最大电力生产商Axpo Group运营。该公司还负责使用道路，桥梁，水坝湖，发电厂和大坝的周围地区的检查和开发。

大坝的混凝土结构旨在承受极端的负载，仅每10000年就会发生一次。这将确保它不会冒着山谷人民的生命和生计的风险。多么强烈的建筑，大坝及其周围环境的行为以及建筑状态被Axpo人员强烈地观察到。

Axpo has an inhouse team of surveyors, with three of them trained to use Leica Aibot for surveying tasks. Thorsten Zimmer, an engineering surveyor at Axpo, is responsible for the inspection project in Lai da Nalps.

“Using a UAV has widened our toolbox of available equipment technologies we can use for our daily tasks. Total stations, GNSS rovers and smaller UAVs are as common tools for us as it is the Leica Aibot,”said Zimmer.

Game changer technology in dam inspection

在使用无人机进行测量之前，用于大坝检查目的的一种选择是从大坝下方和周围的山墙拍摄图像。对于Lai da Nalps大小的大坝，测量师偶尔不得不爬上周围的山丘，正确放置相机并拍照，最后覆盖了整个墙壁。另一种选择是沿着大坝的外部上下移动，站在篮子或缆车内，并记录那里的所有内容。即使有精确的计划和完美的位置，这些方法也非常耗时，有时甚至是危险的，并且无法像从大约10 m的距离处朝着大坝面对大坝相处的高度详细的图像和质量结果。

在拥有Leica Aibot之前，AXPO团队已经是Aibotix Aibot X6的用户，他们使用了几年的测量。现在是时候升级了，因为飞行时间开始成为以前的Aibot的挑战。以前在大规模检查中 - 由于可实现的飞行时间较短 - 一个人负责为电池充电。有了新的Leica Aibot测量师，可以利用更多的时间和精力来关注检查，而不仅仅是将系统保持在空中。

Surveying with Leica Aibot

Every dam Axpo operates is planned to have a full UAV inspection every five years using the Aibot. The inspection of a large dam takes two to three days and approximately 10 hours of total flight time. During the flight, the Aibot takes automatic images every two seconds, enabling the pilot to focus just on flying the copter at a constant height and distance close to the wall. The inspection is a two-person job: one operates the UAV with a focus on the flying position, speed and height, while the other person observes the surroundings, focusing on the quality and overlap of the photos taken as well as the status of the batteries.

Axpo uses a Leica Aibot AX20 UAV solution equipped with Sony α7RII sensor and a 55 mm lens. The 42 MP and crisp clear images ensure that data and results are accurate. To create an accurate and reliable point cloud, Axpo uses a Leica Nova TS60 total station to measure control points for post-processing of the data. The dam has several visible elements that can be used as control points, to be able to position and scale the point cloud. Measuring and documenting the control points can be done before, in between or after the flights.

“The conditions at the dam are challenging because of the sheer size or the arching dam and limited access to GPS. We needed a stable UAV that the pilot can easily operate because sometimes one has to fly without the assistance of GPS yet still holding the UAV in a stable and safe position. We use Leica Aibot because it is easy and safe to operate along our large dams and because we are able to have high-resolution images of the outside faces of our dams, which are needed to achieve the level of detail we require for the end result and the final 3d-model”comments Zimmer.As surveyors we usually choose the solution that fits for the task: for some tasks we use for instance a total station, a scanner or a smaller UAV, especially for indoor inspections, and for other projects the Aibot is the right solution – or even a combination of all”.

在一年中无雪的时候，测量师忙于对水坝进行检查。收集到的数据和图像将在冬季被地质学家和测量师进行分析。结果是对大坝的长期分析的一部分，以计划如果需要进行任何预防性翻新以及何时进行预防性翻新。

Endless possibilities

Surveying UAVs change the geospatial industry and offer enormous potentials for surveyors. Axpo uses the Aibot for the inspection of several active dams and for other indoor and outdoor surveying projects.

1. The company uses Leica Aibot to inspect the inaccessible parts of the dam. Once water levels are low, the team inspects the structures of the dam that are usually under water. The visual inspection of the submerged structure is done by combining unmanned UAV inspection technology and manned inspection from the structure.
2. Flood modelling is also an interesting project for UAVs to mitigate risks related to dam spilling. Geologists investigate potentially risky masses of land and rock that could slide into the dam lake. Volumes of those are calculated and then used in careful what-if analyses.
3. 建筑项目和支持他们的基础设施是AXPO的大型测量项目，也可以由无人机捕获的数据支持。
4. Axpo also uses the Aibot for documentation of river banks by flying along inaccessible areas and for certain planning purposes.

“ Leica Aibot是一种适合我们目的的解决方案，尤其是针对大型大坝的大型和详细的检查。有趣的是，Leica Aibot的多功能性以及我们的团队可以使用多少方式，”总结说Zimmer。

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