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Three-dimensional laser scanning for geometry documentation and construction management of highway tunnels during excavation.

Gikas V - Sensors (Basel) (2012)

Bottom Line: This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels.Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction.Specific case studies are considered based on two construction sites in Greece.

View Article: PubMed Central - PubMed

Affiliation: School of Rural and Surveying Engineering, National Technical University of Athens, 9 I Polytechniou Str., Zographou, Athens 15780, Greece. vgikas@central.ntua.gr

ABSTRACT
Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered.

No MeSH data available.


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Differences in formwork geometry sub-sections obtained between nominal values and laser scanning surveys.
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f15-sensors-12-11249: Differences in formwork geometry sub-sections obtained between nominal values and laser scanning surveys.

Mentions: As shown in Figure 15, the nominal formwork cross-section geometry is represented by a series of connecting circumference cylindrical segments (notated as left, central and right). Therefore, data analysis involved partition of the point cloud into three pieces, each of them corresponding to a clearly defined geometric entity of the formwork, and fitting (using least squares) an appropriate solid figure (cylinder) to it. Besides, each of the three point clouds was further partitioned in two parts (front and rear), so that, detailed geometry statistics were produced for all sub-regions of the formwork. The outcome of the least squares adjustment for all sub-areas are shown in Figure 15. Analysis of these results for the front part indicates that, the arc radii of both sides of the formwork (left and right sections) deviate from their nominal values by less than 2.0 cm, whereas the top of the form (central section) exceeds the theoretical value by 2.8 cm—a difference, nearly twofold of the dimensional tolerance. Interestingly, from the same plot is evident that deviations from the nominal values are smaller at the rear of the formwork. These findings are of interest to the project owner and the contractor (e.g., 3 cm mean difference in the circumferential curvature radius for a 2 km long tunnel translates to 2,800 m3 extra (or less) lining material), and in certain cases (especially, for railway and metro tunnels) might be critical for the clearance traffic border line. The advantage of the laser scanning approach is that the uncertainties can be quantified and visualized, so that, they can be directly compared with the construction specifications for quality control purposes.


Three-dimensional laser scanning for geometry documentation and construction management of highway tunnels during excavation.

Gikas V - Sensors (Basel) (2012)

Differences in formwork geometry sub-sections obtained between nominal values and laser scanning surveys.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472883&req=5

f15-sensors-12-11249: Differences in formwork geometry sub-sections obtained between nominal values and laser scanning surveys.
Mentions: As shown in Figure 15, the nominal formwork cross-section geometry is represented by a series of connecting circumference cylindrical segments (notated as left, central and right). Therefore, data analysis involved partition of the point cloud into three pieces, each of them corresponding to a clearly defined geometric entity of the formwork, and fitting (using least squares) an appropriate solid figure (cylinder) to it. Besides, each of the three point clouds was further partitioned in two parts (front and rear), so that, detailed geometry statistics were produced for all sub-regions of the formwork. The outcome of the least squares adjustment for all sub-areas are shown in Figure 15. Analysis of these results for the front part indicates that, the arc radii of both sides of the formwork (left and right sections) deviate from their nominal values by less than 2.0 cm, whereas the top of the form (central section) exceeds the theoretical value by 2.8 cm—a difference, nearly twofold of the dimensional tolerance. Interestingly, from the same plot is evident that deviations from the nominal values are smaller at the rear of the formwork. These findings are of interest to the project owner and the contractor (e.g., 3 cm mean difference in the circumferential curvature radius for a 2 km long tunnel translates to 2,800 m3 extra (or less) lining material), and in certain cases (especially, for railway and metro tunnels) might be critical for the clearance traffic border line. The advantage of the laser scanning approach is that the uncertainties can be quantified and visualized, so that, they can be directly compared with the construction specifications for quality control purposes.

Bottom Line: This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels.Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction.Specific case studies are considered based on two construction sites in Greece.

View Article: PubMed Central - PubMed

Affiliation: School of Rural and Surveying Engineering, National Technical University of Athens, 9 I Polytechniou Str., Zographou, Athens 15780, Greece. vgikas@central.ntua.gr

ABSTRACT
Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered.

No MeSH data available.


Related in: MedlinePlus