gyroscopic verifications in tunnel surveying aleks kubilius, mike vernikmonteith & sutherland...

Gyroscopic Verifications in Tunnel

Surveying

ALEKS KUBILIUS, MIKE VERNIK MONTEITH & SUTHERLAND LTD.

MONTEITH & SUTHERLAND LTD.

For over 50 years Monteith & Sutherland Ltd. have been providing geospatial solutions. We are reputable and well recognised experts in high precision engineering surveys, tunnel surveying, settlement monitoring, and complex geodetic horizontal and vertical control networks.


WHO WE ARESpecialised employees from all over the world


GEOSPATIAL SOLUTIONS

• Engineering Geomatics• High Definition Scanning• Control surveys

• Topographic surveys• Hydrographic surveys• GIS


DELIVERING RESULTS

• Health & Safety• Passionate team work• Quality Assurance• Foolproof project

deliverables• Design, field, finish


GEOMATIC PROJECT COORDINATION


Primary control

Secondary control

Tertiary control

PRIMARY CONTROL NETWORK


• Verify coordinate system and datum• Establish relationship between datum and project• Static GPS observations• Maintain long-term fixed coordinates

SECONDARY CONTROL NETWORK


• Establish relationship to Primary Network• Maintain absolute Primary Network accuracy• Triangulate precise and accurate relative Secondary Network• Maintain coordinates for extended periods of time

TERTIARY CONTROL NETWORK


• Connect to Secondary Network• Rapid Total Station positioning• Conduct various engineering works• Short-term longevity

TUNNEL SURVEY INSTRUMENTATION


• Global Positioning System (GPS): rapid-static absolute position• Total Station (TPS): high precision coordinate transfer – angular and

distance• Digital level: high precision elevation transfer• Gyromat: true geodetic north orientation

TUNNEL SURVEY NETWORKS


• Coordinates are established and connected at ground level, sub-surface traversing connects terminal points

• Coordinate transfer occurs at either open or vertical shafts

• Several angular and distance measurements between instrument stations and foresight stations complete the transfer

GYROMAT TUNNEL AUDIT


1. Reconnaissance2. Surface baseline campaign3. Tunnel campaigns4. Results5. Alignment

GYROMAT CALIBRATION


GYROMAT APPLICATION


Establish gyro-surveyed coordinates in relation to an existing network. The collection of data will be achieved with a combination of conventional total station and gyro-survey equipment. The task results will ultimately provide quality assurance and potential adjustments to the existing network and tunnelling works.


Surveying


WHAT COULD POSSIBLY GO WRONG?


SURVEYING IN TUNNELS

PREDICTABLE ERROR DISTRIBUTION: UNNOTICEABLE TO SIGNIFICANT


00°00’15” @ 20m = 0.001m ONLY

DIA 20m

SHAFT


WITH ONLY ONE MINOR GEOMETRICAL DEVIATION

INDUCED IN UNREALISTICALLY IDEAL CONDITIONS.

00°00’15” @ 1400m = 0.100m!00°00’15” @ 1900m ≈ 0.150m!


REAL WORLD SHAFT AND TUNNEL CONDITIONS:

SIGNIFICANT AND UNPREDICTABLE TEMPERATURE

AND HUMIDITY AMPLITUDES

ALONG ACROSS

AND


REAL WORLD IR BEAM BEHAVIOUR:

- Dynamic heavily layered air- Varying Humidity- Dust

SCATTERINGAND

REFRACTIONUNPREDICTABLE

BEAM TRAVEL BACK?


Recent case study from the local transit project:

00°00’15”


10

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

OUT OF

TOLERANCE!≈80%

HOW IT WOULD LOOK WITHOUT GYRO CORRECTION:


Gyro-Grid Azimuth for:5 - 6Meas. Station Target Easting Station Northing Station Easting Target Northing Target Merid. Conv. Raw Gyro Azimuth

(m) (m) (m) (m) (gon) (gon) 1 5 6 309135.865 4839412.062 309181.251 4839429.595 -0.04129 76.57562 76.57633 76.57684 76.57645 76.57706 76.57847 76.5762 76.5765

Average Raw Gyro Azimuth Meridian Conv. Average Raw GA + MC Gyro Grid Az (Gon) Gyro Grid Az (D°M'S")

76.5765 -0.04129 76.5353 76.5285 68°52'32''

Δ Gyro Grid Az - Pre-Gyro

Grid AzGon -0.0029

D°M'S" 359°59'51''

Inverse 00°00'09''

Gyro-Grid Azimuth for:7 - 8Meas. Station Target Easting Station Northing Station Easting Target Northing Target Merid. Conv. Raw Gyro Azimuth

(m) (m) (m) (m) (gon) (gon) 1 7 8 309041.272 4839384.358 309089.015 4839402.148 -0.04039 77.34062 77.33683 77.33694 77.33645 77.33956 77.33857 77.3377 77.3375

Average Raw Gyro Azimuth Meridian Conv. Average Raw GA + MC Gyro Grid Az (Gon) Gyro Grid Az (D°M'S")

77.3375 -0.04039 77.2971 77.2904 69°33'41''

Δ Gyro Grid Az - Pre-Gyro

Grid AzGon -0.0023

D°M'S" 359°59'52''Inverse 00°00'08''


• Drilling contractor• Interference with utilities• Interference with traffic• Considerable interference with mining production• Strict plumb requirements• Damage to tunnel structure• Post-survey sealing / backfill costs• Higher potential for compromising precision and

accuracy

WHY NOT AN ALIGNMENT HOLE INSTEAD?


Surveying


gyroscopic verifications in tunnel surveying aleks kubilius, mike vernikmonteith & sutherland...

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