The Delft approach, a method for the deformation analysis, is presented in this article.Based on geodetic measurements, the statistical significance of displacements at the surface is determined with statistical methods.A numerical example shows the effectiveness of the presented method.
During construction of the Šentvid tunnel a unique opportunity arose to measure the 3D displacements ahead of the motorway tunnel excavation face, since the exploratory tunnel was already constructed in the axis of the main tunnel. According to reviewed literature such measurements had not been performed yet and several problems regarding equipment and complete scheme of the experiment needed to be overcome. The paper gives a brief description of the Šentvid tunnel project, presents significant factors that affected the choice of the geodetic equipment and describes the scheme of the experiment. A special attention is focused on the problems relating to the operation of the instrument in demanding environmental conditions (water, dust).
This article deals with the characteristics of deformation of a body or a figure represented by discrete points of geodetic network. In each point of geodetic network kinematic quantities are considered normal strain, shear strain, and rotation. They are computed from strain and rotation tensors represented by displacement gradient matrix on the basis of known point displacement vector. Deformation analysis requires the appropriate treatment of kinematic quantities. Thus statistical properties of each quantity in a single point of geodetic network have to be known. Empirical results have shown that statistical properties are strongly related to the orientation in single point and local geometry of the geodetic network. Based on the known probability distribution of kinematic quantities the confidence areas for each quantity in a certain point can be defined. Based on this we can carry out appropriate statistical testing and decide whether the deformation of network in each point is statistically significant or not. On the other hand, we are able to ascertain the quality of the geometry of the geodetic network. The known characteristics of the probability distributions of two strain parameters and rotation in each point can serve as useful tools in the procedures of optimizing the geometry of the geodetic networks.
This article presents a method for measuring the geometry of crane rails with terrestrial laser scanning (TLS). Two sets of crane rails were divided into segments, their planes were adjusted, and the characteristic rail lines were defined. We used their profiles to define the positional and altitude deviations of the rails, the span and height difference between the two rails, and we also verified that they complied with the Eurocode 3 standard. We tested the method on crane rails at the hydroelectric power plant in Krško and the thermal power plant in Brestanica. We used two scanning techniques: "pure" TLS (Riegel VZ-400) and "hybrid" TLS (Leica MS50) scanning. This article's original contribution lies in the detailed presentation of the computations used to define the characteristic lines of the rails without using the numeric procedures from existing software packages. We also analysed the influence of segment length and point density on the rail geometry results, and compared the two laser scanning techniques. We also compared the results obtained by terrestrial laser scanning with the results obtained from the classic polar method, which served as a reference point for its precision.
This article deals with practical examples of the applications of modern tachymeters in the determination of the nonverticality of high industrial chimneys, as an alternative to the classic methods.The possibility of a reflectorless measuring mode to determine the point cloud at the chimney's circumference is described.Using these points, we are able to model the chimney as a mathematically correct body using the least squares adjustment method.Subsequently, the unknown nonverticality of the chimney is determined as the deviation of the primary axis of the modelled body from the vertical.
Cerkveni zvoniki so bili zaradi svoje oblike in visje postavitve v preteklosti primerne orientacijske tocke pri detajlni izmeri. Z razvojem metod satelitske izmere in predvsem uvedbo koordinatnega sistema D96/TM so pocasi izgubljali pomen. Kljub temu so v primerjavi s talnimi trigonometricnimi tockami vecinoma ostali nedotaknjeni. Kot taksni omogocajo dolocitev transformacijskih parametrov med starim in novim koordinatnim sistemom. Zato potrebujemo dolocitev njihovih položajev tudi v novem koordinatnem sistemu. V prispevku opisujemo postopek dolocitve položaja cerkvenega zvonika s terestricnim laserskim skeniranjem (TLS) na primeru obeh zvonikov Trnovske cerkve. Postopek vkljucuje dolocitev koordinat oslonilnih tock za georeferenciranje oblakov tock. To zahteva dolocitev geodetskega datuma s kombinacijo izmere GNSS in geometricnega nivelmana ter klasicno izmero geodetske mreže z izravnavo proste mreže in uporabo postopka S-transformacije. Na podlagi georeferenciranih oblakov tock smo dolocili položaj trigonometricne tocke zvonika z izravnavo parametrov krogle. Podatke filtriramo z algoritmom RANSAC, tako da imamo v izravnavi res le tocke, ki pripadajo krogli. Rezultate smo primerjali s položaji, dolocenimi na podlagi klasicne terestricne geodetske izmere.
Investigating the thickness of ice walls is a formidable pursuit, especially considering the dynamic nature of the environment and the rapid changes in ice conditions. With the use of terrestrial laser scanning (TLS), further compounded by the influence of unfrozen droplets on TLS measurements, this challenge is heightened, because the presence of droplets can adversely affect the accuracy and reliability of measurements. The study aimed to procure 3D models of the artificial climbing wall in Mlačca Gorge, Slovenia, to help climbers in charting diverse climbing routes prior to ascent. Concurrently, the research endeavor sought to deepen our understanding of TLS application in demanding icy terrain. This study unveils the outcomes of successive TLS measurements conducted during the winter of 2021, marked by the most significant thickening of the ice wall in the previous four years. Notably, the terrestrial surveys unveiled the pivotal influence of the laser scanner's wavelength on beam reflectivity, in addition to the consequential roles played by the angle of incidence of the laser beam on the ice wall and atmospheric moisture concentration in the gorge.
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