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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

Raw point cloud data obtained for the Tempi T1 project (a), (b) and cross-section profiles extracted (c).
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f11-sensors-12-11249: Raw point cloud data obtained for the Tempi T1 project (a), (b) and cross-section profiles extracted (c).

Mentions: For the case of the Tempi T1 tunnel the TCRM 1101 Plus spatial station was used to manually measure profiles at intervals 1.5 m over a tunnel portion 50 m long, collecting points every 1 m on each section. The same tunnel portion was measured using the TCRM 1101 Plus and TMS PROwin® software at intervals of 1.5 m and every 1.0 m on each section. Finally, the same section was surveyed using the ScanStation 2 TLS from two locations spaced by 45 m (Figure 11). The limits of horizontal and vertical point spacing were defined so that, each cross-section is reconstructed using a minimum of 2,000 points. Figure 12 shows summary results for all three observation scenarios obtained at 28 cross-section locations. Figure 12(a) contains the profile area differences computed between the nominal values and those measured for each observation technique. From this plot it is evident that the over-break area increases from ∼7 m2 to ∼12 m2 and concludes to ∼10 m2. This fluctuation in over-cutting area represents a deviation between design and actually excavated volumes in the order of 6.4% to 11.0%, and might be due to variations in the geologic conditions or the blast process. However, the important thing to note from this diagram is that all measuring techniques exhibit the same variation pattern indicating consistency in the results obtained for each method. Also, as expected, the TLS method results in overall smaller differences due to an increased detail in the raw data. Furthermore, in order to examine the impact of the measuring technique in over-break volume computations, Figure 12(b) depicts two estimates. It shows the differences of inter-profile (i.e., between consecutive sections) over-break volumes obtained between the manually and automatic total station surveys and those measured with the TLS method respectively. A thorough examination of this plot suggests that the observed differences in over-break volume computation can vary up to 1.4 m3 (∼6%) and 0.4 m3 (∼2%) per advancement meter, for the manual and automatic total station (profiler) surveys compared to the TLS method respectively. Notably, such differences, for a 2 km long tunnel, translate in an over estimate of concrete quantities of 2,800 m3 and 800 m3 depending which method is used.


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

Gikas V - Sensors (Basel) (2012)

Raw point cloud data obtained for the Tempi T1 project (a), (b) and cross-section profiles extracted (c).
© Copyright Policy
Related In: Results  -  Collection

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

f11-sensors-12-11249: Raw point cloud data obtained for the Tempi T1 project (a), (b) and cross-section profiles extracted (c).
Mentions: For the case of the Tempi T1 tunnel the TCRM 1101 Plus spatial station was used to manually measure profiles at intervals 1.5 m over a tunnel portion 50 m long, collecting points every 1 m on each section. The same tunnel portion was measured using the TCRM 1101 Plus and TMS PROwin® software at intervals of 1.5 m and every 1.0 m on each section. Finally, the same section was surveyed using the ScanStation 2 TLS from two locations spaced by 45 m (Figure 11). The limits of horizontal and vertical point spacing were defined so that, each cross-section is reconstructed using a minimum of 2,000 points. Figure 12 shows summary results for all three observation scenarios obtained at 28 cross-section locations. Figure 12(a) contains the profile area differences computed between the nominal values and those measured for each observation technique. From this plot it is evident that the over-break area increases from ∼7 m2 to ∼12 m2 and concludes to ∼10 m2. This fluctuation in over-cutting area represents a deviation between design and actually excavated volumes in the order of 6.4% to 11.0%, and might be due to variations in the geologic conditions or the blast process. However, the important thing to note from this diagram is that all measuring techniques exhibit the same variation pattern indicating consistency in the results obtained for each method. Also, as expected, the TLS method results in overall smaller differences due to an increased detail in the raw data. Furthermore, in order to examine the impact of the measuring technique in over-break volume computations, Figure 12(b) depicts two estimates. It shows the differences of inter-profile (i.e., between consecutive sections) over-break volumes obtained between the manually and automatic total station surveys and those measured with the TLS method respectively. A thorough examination of this plot suggests that the observed differences in over-break volume computation can vary up to 1.4 m3 (∼6%) and 0.4 m3 (∼2%) per advancement meter, for the manual and automatic total station (profiler) surveys compared to the TLS method respectively. Notably, such differences, for a 2 km long tunnel, translate in an over estimate of concrete quantities of 2,800 m3 and 800 m3 depending which method is used.

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