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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.


Related in: MedlinePlus

Factors affecting TLS data quality in tunnel construction surveys.
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f2-sensors-12-11249: Factors affecting TLS data quality in tunnel construction surveys.

Mentions: In general, modern TLS systems are robust enough to cope with the demanding operation conditions (such as dust and damp) found in the underground environment. Besides, TLS can operate effectively in darkness as the laser beam stands itself a light source. However, it is pointed out that despite the many advantages that induces the introduction of the laser scanning method in tunneling; its use implies a number of challenges and difficulties. In addition to certain limitations discussed already, the point cloud produced by TLS might not fully sample the scanning surface due to shadows relating to the relative geometry (viewing angles) between the instrument and the scanned section. Also, the presence of reflective objects (such as, equipment and water) in the field of view of the instrument can affect the recognition of targets (see Figure 2). In unstable rock conditions the scanning process might be furthered challenged. For example, it might be unsafe to set up the scanner close to an unsupported face, whereas long scanning sessions can lead unsafe conditions getting worse. As seen with operational and processing limitations that imply the use of the method, is inferred that laser scanning should not be regarded as an alternative to traditional measurement methods, but as a complement to well established surveying engineering practices. To this effect Table 2 attempts a classification of TLS usage in tunneling based on the description overview outlined in this section.


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

Gikas V - Sensors (Basel) (2012)

Factors affecting TLS data quality in tunnel construction surveys.
© Copyright Policy
Related In: Results  -  Collection

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

f2-sensors-12-11249: Factors affecting TLS data quality in tunnel construction surveys.
Mentions: In general, modern TLS systems are robust enough to cope with the demanding operation conditions (such as dust and damp) found in the underground environment. Besides, TLS can operate effectively in darkness as the laser beam stands itself a light source. However, it is pointed out that despite the many advantages that induces the introduction of the laser scanning method in tunneling; its use implies a number of challenges and difficulties. In addition to certain limitations discussed already, the point cloud produced by TLS might not fully sample the scanning surface due to shadows relating to the relative geometry (viewing angles) between the instrument and the scanned section. Also, the presence of reflective objects (such as, equipment and water) in the field of view of the instrument can affect the recognition of targets (see Figure 2). In unstable rock conditions the scanning process might be furthered challenged. For example, it might be unsafe to set up the scanner close to an unsupported face, whereas long scanning sessions can lead unsafe conditions getting worse. As seen with operational and processing limitations that imply the use of the method, is inferred that laser scanning should not be regarded as an alternative to traditional measurement methods, but as a complement to well established surveying engineering practices. To this effect Table 2 attempts a classification of TLS usage in tunneling based on the description overview outlined in this section.

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