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Optimization of Deformation Monitoring Networks using Finite Element Strain Analysis
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering. WSP Civils, Department of Geographic Information and Asset Management.ORCID-id: 0000-0003-1602-4771
University West, Department of Engineering Science.ORCID-id: 0000-0003-0067-8631
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering.ORCID-id: 0000-0002-8792-3646
2018 (engelsk)Inngår i: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 12, nr 2Artikkel i tidsskrift, Editorial material (Fagfellevurdert) Published
Abstract [en]

An optimal design of a geodetic network can fulfill the requested precision and reliability of the network, and decrease the expenses of its execution by removing unnecessary observations. The role of an optimal design is highlighted in deformation monitoring network due to the repeatability of these networks. The core design problem is how to define precision and reliability criteria. This paper proposes a solution, where the precision criterion is defined based on the precision of deformation parameters, i.e. precision of strain and differential rotations. A strain analysis can be performed to obtain some information about the possible deformation of a deformable object. In this study, we split an area into a number of three-dimensional finite elements with the help of the Delaunay triangulation and performed the strain analysis on each element. According to the obtained precision of deformation parameters in each element, the precision criterion of displacement detection at each network point is then determined. The developed criterion is implemented to optimize the observations from the Global Positioning System (GPS) in Skåne monitoring network in Sweden. The network was established in 1989 and straddled the Tornquist zone, which is one of the most active faults in southern Sweden. The numerical results show that 17 out of all 21 possible GPS baseline observations are sufficient to detect minimum 3 mm displacement at each network point.

sted, utgiver, år, opplag, sider
2018. Vol. 12, nr 2
HSV kategori
Forskningsprogram
Geodesi och geoinformatik
Identifikatorer
URN: urn:nbn:se:kth:diva-219571DOI: 10.1515/jag-2017-0040Scopus ID: 2-s2.0-85045196739OAI: oai:DiVA.org:kth-219571DiVA, id: diva2:1163698
Merknad

QC 20180115

Tilgjengelig fra: 2017-12-07 Laget: 2017-12-07 Sist oppdatert: 2018-04-04bibliografisk kontrollert
Inngår i avhandling
1. Optimal Design in Geodetic GNSS-based Networks
Åpne denne publikasjonen i ny fane eller vindu >>Optimal Design in Geodetic GNSS-based Networks
2017 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

An optimal design of a geodetic network helps the surveying engineers maximise the efficiency of the network. A number of pre-defined quality requirements, i.e. precision, reliability, and cost, of the network are fulfilled by performing an optimisation procedure. Today, this is almost always accomplished by implementing analytical solutions, where the human intervention in the process cycle is limited to defining the requirements. Nevertheless, a trial and error method can be beneficial to some applications. In order to analytically solve an optimisation problem, it can be classified to different orders, where an optimal datum, configuration, and optimal observation weights can be sought such that the precision, reliability and cost criteria are satisfied.

In this thesis, which is a compilation of six peer-reviewed papers, we optimised and redesigned a number of GNSS-based monitoring networks in Sweden by developing new methodologies. In addition, optimal design and efficiency of total station establishment with RTK-GNSS is investigated in this research.

Sensitivity of a network in detecting displacements is of importance for monitoring purposes. In the first paper, a precision criterion was defined to enable a GNSS-based monitoring network to detect 5 mm displacements at each network point. Developing an optimisation model by considering this precision criterion, reliability and cost yielded a decrease of 17% in the number of observed single baselines implying a reliable and precise network at lower cost. The second paper concerned a case, where the precision of observations could be improved in forthcoming measurements. Thus a new precision criterion was developed to consider this assumption. A significant change was seen in the optimised design of the network for subsequent measurements. As yet, the weight of single baselines was subject to optimisation, while in the third paper, the effect of mathematical correlations between GNSS baselines was considered in the optimisation. Hence, the sessions of observations, including more than two receivers, were optimised. Four out of ten sessions with three simultaneous operating receivers were eliminated in a monitoring network with designed displacement detection of 5 mm. The sixth paper was the last one dealing with optimisation of GNSS networks. The area of interest was divided into a number of three-dimensional elements and the precision of deformation parameters was used in developing a precision criterion. This criterion enabled the network to detect displacements of 3 mm at each point.

A total station can be set up in the field by different methods, e.g. free station or setup over a known point. A real-time updated free station method uses RTK-GNSS to determine the coordinates and orientation of a total station. The efficiency of this method in height determination was investigated in the fourth paper. The research produced promising results suggesting using the method as an alternative to traditional levelling under some conditions. Moreover, an optimal location for the total station in free station establishment was studied in the fifth paper. It was numerically shown that the height component has no significant effect on the optimal localisation.

sted, utgiver, år, opplag, sider
KTH Royal Institute of Technology, 2017. s. 72
Serie
TRITA-SOM, ISSN 1653-6126 ; 2018-01
HSV kategori
Forskningsprogram
Geodesi och geoinformatik
Identifikatorer
urn:nbn:se:kth:diva-221067 (URN)978-91-7729-631-7 (ISBN)
Disputas
2018-02-09, Kollegiesalen, Brinellvägen 8, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Merknad

QC 2080115

Tilgjengelig fra: 2018-01-15 Laget: 2018-01-11 Sist oppdatert: 2018-02-26bibliografisk kontrollert

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