dam safety monitoring is essential to ensure the stable operation of dams and prevent potential safety accidents. It can not only help us find the abnormal changes of the dam structure in time, but also provide a scientific basis for the maintenance and management of the dam.
aims to strengthen the safety monitoring of hydropower dams and improve the level of operational safety.
is used to guide the safety monitoring of earth-rock dams.
The dam deformation monitoring is an important means to ensure the safe operation of the dam, involving a variety of technologies and methods.
After investigation, it is found that small reservoirs usually have the following problems in safety monitoring:
(1) Automatic total station monitoring system
①system cost: Compared with traditional monitoring systems, automatic total station monitoring systems may have lower initial investment and maintenance costs, especially when labor costs are considered;
② High-precision measurement: In short distances, the automatic total station monitoring system can provide millimeter or even sub-millimeter measurement accuracy, which is essential for application scenarios that require fine monitoring;
③ 3D coordinate acquisition: The system can provide 3D coordinate data of monitoring points, which makes it very useful in spatial analysis and 3D modeling.
①Range limitation: Automatic total stations usually provide high-precision measurements at short distances. Generally, the distance from the total station station station to the prism does not exceed 1000 meters. Beyond this distance, the measurement accuracy may be reduced;
②Line of sight requirements: the target prism from the total station to the monitoring point must maintain visibility, that is, there is no obstacle blocking the line of sight. This limits the use of total stations in environments with limited line of sight;
③Meteorological conditions are sensitive: the measurement results may be affected by meteorological conditions, such as strong winds, rain and fog and other bad weather may reduce the measurement accuracy or cause the equipment to fail to work normally;
④ Single point dynamic tracking: an instrument can only dynamically track and measure one prism at a time, which limits the ability to monitor multiple points at the same time and may affect the monitoring efficiency;
⑤Equipment Cost: Although the system cost may be low, the high-precision total station and its accessories may still require a relatively high initial investment.
(2) Sensor monitoring system
Low cost: Sensor monitoring systems typically have a lower cost than traditional monitoring methods, especially when low-cost sensors are used for large-scale deployments;
②High degree of automation: the sensor monitoring system can realize highly automated data collection and processing, reduce manual intervention, and improve monitoring efficiency;
③Direct monitoring of physical causes: Many sensors can directly measure physical quantities that cause deformation or other structural responses, such as stress, strain, temperature, humidity, etc., thereby providing direct physical cause analysis;
④ Real-time monitoring, high precision, easy integration, etc.
disadvantage is that the deformation usually obtained is one-dimensional, local, relative, and the measurement range is small.
(3) Photogrammetric system
① comprehensiveness: the deformation of any point on the surface of the deformed body can be measured at the same time to provide comprehensive spatial deformation monitoring;
②Three-dimensional information acquisition: It can provide complete and instantaneous three-dimensional spatial information, which is helpful for accurate three-dimensional modeling of structures or terrain;
③Fast measurement speed: Compared with traditional contact measurement methods, photogrammetry can quickly obtain a large amount of data and improve measurement efficiency;
④Non-contact measurement: Realize non-contact measurement, avoid interference to the measured object, especially suitable for difficult to contact or dangerous measurement environment;
⑤ High flexibility: the photogrammetry system can be used in different environments and conditions, with high adaptability;
⑥ high precision: modern photogrammetry technology, such as digital photogrammetry, can provide very high measurement accuracy;
⑦ Suitable for large-scale monitoring: especially suitable for large-scale terrain and structural monitoring, such as landslide, building deformation, etc;
® real-time or near real-time monitoring: Some photogrammetry systems can achieve real-time or near real-time monitoring, which is very useful for dynamically changing monitoring objects.
Disadvantages:Although the photogrammetry system has the above-mentioned advantages, there may be some limitations in practical applications, such as the dependence on lighting conditions, the complexity of image processing and analysis, and the need for high-precision photographic equipment. However, with the development of technology, these limitations are gradually being overcome, making photogrammetry systems an increasingly popular monitoring tool.
(4) laser interferometer
laser interferometer is a high-precision measurement tool, usually used to measure small displacements or changes. Its advantages include:
①can provide nano-scale measurement accuracy, is the ideal choice for measuring small displacement and change;
② Non-contact measurement, fast response and high resolution;
laser interferometers include:
① Target tracking problem: When the target point has a large displacement, the laser interferometer may be difficult to track the target continuously. This is because laser interferometers are usually designed to measure very small displacements, and once the target moves beyond its dynamic range or tracking ability, it can lose the target or produce errors.When the displacement of the target point is large;
② Measurement distance limitation: The measurement distance of the laser interferometer is relatively short. They are best suited for short-range measurements and usually work best within a few meters.
(5) interferometric radar analysis
interferometric radar analysis, also known as InSAR(Interferometric Synthetic Aperture Radar) technology, is an interferometric measurement technology that uses radar signals to obtain information about small surface deformations.
principle: InSAR technology uses SAR images obtained from two or more flights to extract elevation information or deformation data of the surface through phase differences between images.
its advantages include:
can provide high-precision, high-resolution ground elevation information
all-weather, all-day working ability, insensitive to atmospheric and seasonal changes
can monitor centimeter-scale or even smaller surface deformation
(6). GNSS deformation monitoring system
GNSS (Global Navigation Satellite System) deformation monitoring is a satellite-based positioning technology, which is widely used in various engineering and environmental monitoring fields.
GNSS deformation monitoring are as follows:
①All-weather, all-day operation: GNSS monitoring system can be carried out 24 hours a day, not limited by day or night
②No visibility: GNSS base stations do not need to maintain direct line-of-sight contact, which allows them to be deployed in areas with complex terrain
③Large range capability: GNSS technology can cover a large range and is suitable for measuring fixed reference points and monitoring target points within a range of several kilometers.
④Directly provide three-dimensional coordinates: GNSS monitoring can directly provide the X, Y, Z three-dimensional coordinates of the monitoring point, simplifying the data processing process;
⑤Synchronous measurement: Different monitoring points can be measured synchronously, which is very important for understanding the deformation mode of the overall structure;
⑥ high sampling rate, the current receiver sampling rate of hkmt 20~50Hz.
GNSS deformation monitoring technology has the above advantages, it may also face some challenges in practical application, such as signal occlusion, multipath effect, atmospheric delay error and so on.
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