gyromat in tunnelling practice

Geosystems at HxGN LIVE Increasing accuracy in high precision survey with DMT GYROMAT 5000 in combination with LEICA high-end total station

Volker Schäpe, Volker Schultheiß, Norbert Benecke

Version Date: 04.06.14

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DMT GmbH & Co. KG Company profile

DMT is an international technology service provider in the fields of natural resources, safety and infrastructure DMT was founded in 1990 as a merger of 3 companies founded in 1864 In the year 2007 DMT joint the TÜV NORD Group

TÜV Nord Group Headquarters in Hannover, Germany ~1.056 Mio. € annual turnover in 2013 ~9.925 Employees in 70 countries

DMT Group Headquarters in Essen, Germany ~113 Mio. € annual turnover in 2013 ~720 employees

Development department for geo-instruments like GYROMAT 5000 Service department for surveying tasks

1. Introduction of GYROMAT 5000

2. Application for GYROMAT 5000: high accuracy tunnel survey

3. Examples and case studies

Content

DMT GYROMAT 5000 + LEICA total station High precision north finding gyroscope

DIN 18723 Teil 7 (1990) (German Standard for Industry 18723 Part 7 from 1990) A gyroscope (northseeking gyro) is a pendulous suspended, electronic driven gyro, which spin vector is influenced by gravity and earth rotation. It will directed to astronomic north. Implementation of gyro into the GYROMAT

Gyro axis

Suspension tape

ω

Introduction of GYROMAT 5000 Principle of a gyroscope

Highest measuring accuracy.. 0,8 mgon (= 1,2 cm / 1 km)

Short measuring time ………. 6 – 9 minutes

Weight without total station … 11,5 kg

Fully automatic measuring sequence

Preorientation-free measuring method

Individual theodolite equipping with LEICA high-end total stations like TPS1100, TPS1200, TS11, TS15, TS30, TM30 TS50, MS50, TM6100A and others with accuracy better than 1”

GYROMAT 5000 The most accurate precision-surveying gyroscope in the world




Content


Requirements on accuracy of tunnel/roadway position depend on: Used tunneling method (e.g. TBM or blasting ) Use of the tunnel in operation (e.g. high speed railway tunnel / roadway tunnel)

Examples for challenging requirements in accuracy: Predefined demounting construction position with 5 cm variance for the TBM Required alignment accuracy better than 5 cm at each tunnel position for high

speed railway tunnels Required accuracy of 10 cm for cut-through of two underground roadways

High accuracy tunnel survey Requirements on position measurement in tunnels

Establishment of an efficient Survey System including:

Surface network, created e.g. by GNSS

Transfer of surface network into the tunnel via open traverse lines:

Survey point distances in the tunnel range between 50 m and > 200 m Survey points are mostly located at flanks, rarely in the middle of the tunnel Deviations and errors propagate with every survey point Failures in positioning increase with tunnel length

Deviations are unavoidable! In particular:

refraction error plumbing error error propagation

will lead into lateral deviation

High accuracy tunnel survey Surveying and directions in tunneling, some considerations

Target building

Plumbing Error

α β1

β2 β3

q

B S

QL

Real direction with plumbing error q Theoretical direction without plumbing error

Tunnel length [m]

Lateral deflection Plumb error: 1 mm Base length: 10 m

Lateral deflection Plumb error: 1,5 mm

Base length: 8 m

300 4,2 cm

8,0 cm

1.000

14,1 cm

26,5 cm

10.000

141,4 cm

265,2 cm

β1

β2

β3

Start shaft

High accuracy tunnel survey Improvement of accuracy by the use of GYROMAT 5000

Refraction in a tunnel

Theoretical straight-lined beam Real tunnel situation: different

layers of temperatures between the tunnel walls and tunnel centre lead into refraction In reality: curved beam Disregard of refraction leads

into position error QR

Start shaft

Influence of refraction Theoretical position

QR A1

A2

A‘2 A‘1 Δ Δ

North North

Solution: GYROMAT 5000 delivers the absolute north direction for every point. The refraction can be identified


Gyro supported traverse line in the tunnel

Error propagation

Survey points Traverse line Gyro surveyed polygon side

50 – 200 m 500 – 1.000 m





Content


Water supply tunnel for a 420 MW hydropower plant Length: 25,8 km, diameter: 7 – 8 m Driven by two TBM from two sites: intake and outlet 1 Gyro campaign 1 km before planned cut-through Driving status while survey: intake tunnel: 7,5 km

outlet tunnel: 17,5 km Extreme environmental conditions while survey:

temperature up to 42О C; air humidity: 99% Result: determination of significant lateral deviation in

both tunnels of up to 2,5 m at calculated cut-through position

By the way: in consideration of the environmental conditions, 2,5 m lateral deviation is good result for open traverses over these large distances.

Gilgel Gibe II tunnel in Ethiopia Case study: water supply tunnel

Achieved lateral deviation: < 5 cm

Scenario without correction: Lateral deviation of > 2,5 m which corresponds to a third of total tunnel width

Possible consequence of scenario above: Additional construction efforts to correct the direction which would had exceeded multiple the costs and time for gyro campaign

Result of cut-through after correction of driving direction:

Gilgel Gibe II tunnel in Ethiopia Case study: water supply tunnel

690 MW hydropower plant, supplied by two different water reservoirs in the sub-arctic east part of Island mountain region. Total tunnel length: 72 km Driving with 3 TBM from different

starting points Allowance of horizontal deviation

at cut-through positions: < 20 cm Allowance of deviation from the

target direction for every section of 100 m: < 15 cm

Kárahnjúkar Hydro-Electric Project (Island) Case study: water supply tunnel

Challenges for this survey

Extreme length of single tunnel sections Complex geometry with curves and branches leads

to sightings close to the tunnel wall Extreme environmental conditions:

- Outside temperatures below -20О C - Inside temperature range from 0О C to > 40О C High variation of air temperature at tunnel

entrances or ventilation holes Air humidity nearly 100 % Partly water suddenly flows in with temperatures

up to 51О C Facing considerable, unpredictable and

unavoidable refractions at the traverse


Challenges in surveying and alignment


Faultless operation of GYROMAT 3000 and Leica total stations TCA1800 and TS30 even with the extreme weather conditions

Keeping the required accuracy for all cut-through so that extensive rework could be avoided. 20 cm was allowed, 5 cm was achieved

Results:


Challenges for this survey

Extreme total length of 57 km

High demands on accuracy of max. 10 cm lateral deviation at every point

Tunnel work with TBMs from 5 access points. Entrance Sedrun via 800 m deep shaft

Gotthard Basistunnel (Switzerland) High speed railway tunnel

Quelle: R. Stengele (Swissphoto AG)

Gyro campaign in the driving Bodio (15,7 km) 8 Gyro campaigns in

December 2003 and August 2006 with GYROMAT 624 single azimuth surveys in

total with only 22 outliers; 3,5% which were eliminated Determination of 44 reference

azimuths on the surface network and 38 azimuths in the underground network with 602 single survey results


Cut-through Bodio – Faido on 26.10.2006


Achieved deviation at cut-through Bodio – Faido (15,7 km) Lateral: 9,1 cm Vertical: 2,3 cm

Cut-through Bodio – Faido on 26.10.2006

Different voices about the result: Building engineering: This deviation can be compensated by optimizing the interior work Railway engineering: This deviation can be compensated by minimal track moving over 300 m Surveyor: Considerable result Insurance: Risks remain under control


Sewer tunnel project of the City of Portland (Oregon/USA) constructed by TBM (Herrenknecht)

Length of 5,5 km with no remarkable incline or curves, diameter: 5 m

After the short distance of only 500 m tunneling two different survey campaigns one by contractor’s surveyor one by client’s surveyor

showed lateral differences of more than 25 cm

Combined Sewer Overflows Tunnel, Portland, USA West side CSO tunnel project

Problem: Tunneling starts from a haulage shaft of

50 m depth and 18 m diameter Start-up baseline for survey of only 11 m

length Plumbing error of only 2 mm causes

large lateral errors Feared result without measurements:

breakthrough disaster

Measurements: Turning the traverse into right orientation

by only two GYROMAT campaigns Reached result: successful breakthrough

with an accuracy of a few millimeters

Combined Sewer Overflows Tunnel, Protland, USA West side CSO tunnel project

Guidance system for TBM

Source: VMT GmbH

Tunnel survey System

Efficient survey system

Resume

Every tunneling project signifies an investment of several million Euro/Dollars Tunnel survey take place under difficult environmental conditions Small errors have a great impact on the technical and economical success of

the project The nightmare of a tunnel driver can be avoided by three steps:

High accuracy tunnel construction

QR

Gyro control survey as insurance

α β1

β2 β3

q QL β1

β2

β3

DMT GmbH & Co. KG Exploration & Geosurvey Contact: Norbert Benecke Am Technologiepark 1 45307 Essen, Germany Phone: +49 201 172 2012 Fax: +49 201 172 1791 E-mail: [email protected] Internet: www.dmt.de

Thank you for your attention

gyromat in tunnelling practice

Engineering

tunnel position

tunnel deviations

tunnel walls

tunnel range

use of gyromat

high precision survey

plumbing error tunnel

tunnel length deviations