Potential of Terrestrial Laser Scanner techniques and Geographic Information System for Concrete Dam Monitoring (original) (raw)
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STRUCTURAL MONITORING OF A LARGE DAM BY TERRESTRIAL LASER SCANNING
International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences
This paper presents some first results of a project aimed to access the feasibility of monitoring deformations of large concrete dams by terrestrial laser scanning. For this purpose a test field has been established on the dam of the Cancano Lake (Valtellina, Italy). This is made up of a geodetic network materializing a local datum for georeferencing all data acquired at different times. A large number of retro-reflecting targets have been positioned and measured by a total station in the local datum. Moreover, targets have been measured also in captured scans. Some of these have been placed on the dam structure to be used as independent check points, the others in the surroundings to play as ground control point. Three measurement campaigns have been accomplished so far by using two laser scanners: a long range Riegl LMS-Z420i and a medium range Leica HDS 3000. Reported analyses are focused on two main problems: the first one is the accuracy and the stability of georeferencing, which is fundamental to make comparisons between different multi-temporal scans; the second one is the computation of deformation based on the acquired point-clouds. 1 -Mesh vs resmapled point cloud (# of points: 71758) 2 -Polynomial surf. vs res. poin cloud (# of points: 65550) 3 -mesh vs mesh (# of points: 37674) 4 -Polynomial surf. vs Polynomial surf. (# of points: 20971)
Boletim de Ciências Geodésicas, 2013
Applicability of Terrestrial Laser Scanners/Scanning (TLS) in deformation measurement in dams is an active area of study. With the advance of modern technology, accuracy of measurements is much improved by developments in design of terrestrial laser scanners. Currently, this technology is used in large and complex engineering structures such as dams. Although TLS is a high cost technology, it is particularly used in monitoring of dam deformations, due to its speed in obtaining thousands of data points, ability to visualize the scanned object and its environment with high accuracy and ability to take long-range measurements. In order to determine the effect of change in water reservoir levels on body of the dam, TLS are used to take deformation measurements in different time intervals, where the water level was at maximum, minimum and medium levels. This paper provides an overview of terrestrial laser scanning technology for deformation monitoring. The concrete arch dam in Antalya Oy...
OVERVIEW ON TERRESTRIAL LASER SCANNING AS A TOOL FOR DAM SURVEILLANCE
Traditional methods for geometric monitoring of natural structures and infrastructures rely in the observation of a limited number of materialized points which are located on the surface and deemed representative of the structural behavior of the object under study. Using geodetic methods it is possible to determine the Cartesian coordinates, or the displacement vectors, of the referred points within milimetric uncertainty. These geodetic monitoring methods have been in use since the end of the first quarter of the 20th century and are characterized by providing results which are referenced outside the zone under the effects of the object itself and by the specialization of labor, procedures and equipment. For the last two decades, laser scanners, which provide in a few minutes the Cartesian coordinates of millions of points belonging to any reflecting surface, have been used incrementally and successfully for the geometric modeling of civil engineering and natural structures. The development of laser scanners, which occurred outside of the geodetic community, has already incorporated the extensive know-how of the referred community bringing the positional uncertainty of terrestrial laser scanners to values which are comparable to those of the geodetic approach. Terrestrial laser scanning provides, of the reflecting object, an accurate geometric model that can be considered continuous, in practical terms, besides the coordinates of the traditional surface marks provided by geodetic methods. Furthermore, the fusion of radiometric data gathered by other types of sensors, like photo sensors or thermal sensors, can add semantic wealth to the continuous geometric model, thus providing an unprecedented amount of information to the engineer. This information can be used in different phases of the infrastructure lifespan, from the accurate archiving of the foundations, to the structural safety monitoring activities (deformation assessment and assisted visual inspections) or to reverse engineering tasks aiming at the refurbishment of an old infrastructure. LNEC has used this technology since 2003 in a variety of dams and related activities. This paper intends to report on LNEC experience in applying laser scanning technology to dam surveillance, namely on some results obtained in Cabril dam concerning deformation monitoring and assisted visual inspections.
Potential Evaluation of the Terrestrial Laser Scanner in Structural Monitoring: Case Study Maua HPP
Revista Brasileira De Cartografia, 2015
With the purpose of evaluating the potential of using a terrestrial laser scanner in the monitoring of dams, with case study in the Power Plant Maua located in the Tibagi River, on the border between the cities of Ortigueira and TelêmacoBorba, scans were performed in the fi eld in two different times, before and after the formation of its reservoir. The laser point clouds were integrated with data from a survey of robotic total station, in the Cyclone software, to refer all results to the same local topographic system. All data were processed using two different software that allow the detection of displacements by comparing the scan, 3DReshaper and CloudCompare. Some comparison procedures were performed: between the scans performed from equal installation points in different periods, between the scans performed from a point and the dam's overall structure scans, and between the scans of the overall structure in the different periods. The results show a large dependence of the calculation with the meshing process, but in areas of highest density of points, we observed a higher precision of the mesh and a better defi nition of displacements.
Application of Terrestrial Laser Scanning in Identifying Deformation in Thin Arch Dams
2018
Dams are relatively simple hydraulic structures that provide vital services to communities in the United States (U.S.). However, many of the dams in the (U.S.) have surpassed their design life. Dams experience changes from external threats that result in deformation of the structure. Traditional surveying techniques provide limited information on deformation in pre-determined areas of a structure, but the collection effort can often be lengthy. In this research, different instruments used for change detection were reviewed and Terrestrial Laser Scanning (TLS), also known as ground-based Light Detection and Ranging (LiDAR), was selected as the most probable method to accurately evaluate deformation in dams. TLS is a remote sensing instrument that uses light to form a pulsed laser to measure ranges to variable targets, and it provides the ability to measure displacement with high accuracy using dense point clouds collected in a short amount of time. Deformation is identified by measur...
Deformation monitoring of structural elements using terrestrial laser scanner
2019
Civil infrastructure systems is important in terms of both safety and serviceability. So, large structure have been monitored using surveying techniques, while fine-scale monitoring of structural components has been done with geotechnical instrumentation. The advantages and disadvantages of using remote sensing methods, such as terrestrial laser scanning and digital close range photogrammetry, for the purposes of precise 3D reconstruction and the estimation of deflections in structural elements. This paper investigate that terrestrial laser scanner can be used for the monitoring of concrete beams subjected to different loading conditions. The system used does not require any physical targets. The setup was tested, and the beam deflections resulted from the 3D model from terrestrial laser scanner system were compared to the ones from ANSYS program. The experiments proved that it was possible to detect sub-millimeter level deformations given the used equipment and the geometry of the setup. Calculations and analysis of results are presented.
A New Approach for Structural Monitoring of Large Dams with a Three-Dimensional Laser Scanner
Sensors, 2008
Driven by progress in sensor technology, computer methods and data processing capabilities, 3D laser scanning has found a wide range of new application fields in recent years. Particularly, monitoring the static and dynamic behaviour of large dams has always been a topic of great importance, due to the impact these structures have on the whole landscape where they are built. The main goal of this paper is to show the relevance and novelty of the laserscanning methodology developed, which incorporates different statistical and modelling approaches not considered until now. As a result, the methods proposed in this paper have provided the measurement and monitoring of the large "Las Cogotas" dam (Avila, Spain).
A Comparison Method for 3D Laser Point Clouds in Displacement Change Detection for Arch Dams
ISPRS International Journal of Geo-Information, 2021
Dam deformation monitoring can directly identify the safe operation state of a dam in advance, which plays an important role in dam safety management. Three-dimensional (3D) terrestrial laser scanning technology is widely used in the field of deformation monitoring due to its fast, complete, and high-density 3D data acquisition capabilities. However, 3D point clouds are characterized by rough surfaces, discrete distributions, which affect the accuracy of deformation analysis of two states data. In addition, it is impossible to directly extract the correspondence points from an irregularly distributed point cloud to unify the coordinates of the two states’ data, and the correspondence lines and planes are often difficult to obtain in the natural environment. To solve the above problems, this paper studies a displacement change detection method for arch dams based on two-step point cloud registration and contour model comparison method. In the environment around a dam, the stable rock...
Proceedings of the 10th International Conference on Photonics, Optics and Laser Technology, 2022
The main objective of the paper was to evaluate two approaches aimed at tracking small displacements. The first approach is based on the usage of laser targets commonly used for stitching point clouds together. The second approach is based on the estimation of a corner of a prismatic shape and utilizes thin horizontal slices of the shape's point cloud. The corner's location is estimated as an intersection of two straight lines best fitted to the point clouds before and after the corner. It was shown that for both approaches a sub-millimetre accuracy can be achieved. The first approach requires the installation of two laser targets in order to measure the change of the distance between them. The second approach offers more flexibility because it does not require the installation of a laser target. Hence it can be used in the quantitative assessment of structural damage in the aftermath of natural disasters such as earthquakes, fires, tsunamis, landslides and hurricanes, to name a few.