Download - ADMS Project - Viaduct Monitoring

8/12/2019 ADMS Project - Viaduct Monitoring

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MONITORING SOLUTION PROVIDERS PTE LTD

Protecting Your Future with Monitoring Solution 1 of 12 Viaduct Monitoring

Viaduct MonitoringViaduct MonitoringViaduct MonitoringViaduct MonitoringThe Buona Vista MRT StationBuona Vista MRT StationBuona Vista MRT StationBuona Vista MRT Station (EW21/CC22)(EW21/CC22)(EW21/CC22)(EW21/CC22) is a Mass Rapid Transit (MRT) station locatedin the town of Buona Vista in Singapore that is part of the East West Line and the futureCircle Line (under construction), and serves as an interchange between the two lines. Onthe East West Line, it is between the Dover Station and the Commonwealth Station. Onthe Circle Line (under construction), it is between the Holland Village Station and One-

North MRT Station.

Monitoring Solution Providers Pte Ltd was involved in the monitoring of MRT viaduct atthe existing Buona Vista MRT Station for Land Transport Authority Contract 855, CircleLine Stage 4, Construction and Completion of Holland Village, Buona Vista and KentRidge Stations including One-North Station Fit-Out Works and Tunnels.

The main instruments for Automatic Monitoring System installed on the column andviaduct of the existing East West Line and also at Buona Vista MRT station for the

proposed Circle Line Contract C855 are 2 Total Station located at 23282.652 Easting32205.690 Northing and 23157.409 Easting 32155.077 Northing respectively. Alsoincluded in the system are 38 EL beams installed on both East and West bound of the MRTviaduct from viaduct column E157 E166 and W157-W166.

Equipment Quantity Description of LocationRoboticTotal Station

2 nos. STN1 is located on groundlevel just outside theBored Tunnel

STN2 is located onground level, along theviaduct

MonitoringPrisms onColumnLength

20 nos. Each column contains 2prisms which areapproximately 2m apart(Top/Bottom) to providecolumn tilt information, if

anyMonitoringPrisms onColumnFlange

20 nos. Flange (Left/Right) holdingthe edge of the ViaductBeam (to mount a prism ateach end)

MonitoringPrisms onthe ViaductBeams only

20 nos. Each Viaduct Beams endto be installed with 1 no.prism (Left/Right) toprovide tilt information ofthe beam, in case ofsettlement from thecolumns

Fig 1: Monitoring Site


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ReferencePrism

36 nos. Each monitoring set-uprequires at least 18 nos. ofReference Prism to beinstalled outside theMonitoring Zone

LLLLayout of the Monitoring Prism:ayout of the Monitoring Prism:ayout of the Monitoring Prism:ayout of the Monitoring Prism:

Side View

Section View

Instrument Protection Hut:Instrument Protection Hut:Instrument Protection Hut:Instrument Protection Hut:

2m

VIA DUCT

1.5m highopening

Zinc roofing

Wire MeshSurrounding

1.8m highzinc hoarding

50mm thkconcrete base

Ground Level

2m


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SiteSiteSiteSite PPPPiiiictures:ctures:ctures:ctures:

Picture 1: View from STN1 to the Left of MRT Viaduct of the

Picture 2: View from STN1 to the Center of MRT Viaduct of the

Picture 3: View from STN1 to the Right of MRT Viaduct of the Monitoring


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CONTRACT C855 CCL 4 & 5 Automated Monitoring System For Existing Buona VistaMRT ViaductThe site was surveyed to provide an ultimate solution to the monitoring scheme and someconsiderations during the survey are:1. Position of the Total Station to obtain the best Line1. Position of the Total Station to obtain the best Line1. Position of the Total Station to obtain the best Line1. Position of the Total Station to obtain the best Line- ---of of of of----Sight.Sight.Sight.Sight. Careful consideration wasgiven to the congested vehicles and line of sight to the columns, influence from theexcavation, vibration from heavy vehicles. This prevented the Total Station to be locatedwithin the structure itself as the louvered cladding on the station prevented this best Line-

of-Sight. To overcome the problem, the retry of an obstructed prism point will beincreased to 5 times for capturing all prisms.2. Total Station from either side was not able to obtain a common point observation due to2. Total Station from either side was not able to obtain a common point observation due to2. Total Station from either side was not able to obtain a common point observation due to2. Total Station from either side was not able to obtain a common point observation due tothe widththe widththe widththe width of the station structure.of the station structure.of the station structure.of the station structure. Thus, both Total Stations will have their own ReferencePrisms outside the zone of influence but still remain in the same survey network orcoordinate system.3. Strong fluctuation reading from weather if ELS Beams are installed3. Strong fluctuation reading from weather if ELS Beams are installed3. Strong fluctuation reading from weather if ELS Beams are installed3. Strong fluctuation reading from weather if ELS Beams are installed above the viaduct above the viaduct above the viaduct above the viaduct.The solution was to customize a holding bracket and to select a brand of ELS beam thatuses the bussed system (daisy chain cabling) that could reduce the weight cabling, forinstalling the ELS Beams on the underside of the viaduct without drilling into the viaductThe entire installation works is summarized as follows:- Approval of Method Statement;

Picture 4: View from STN2 to the Center and Right of MRT Viaduct of the

Pictures 5: View from STN2 to the Left of MRT Viaduct of the


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- Installation of Prisms, Total Station Protection Huts and ELS Beams;- Installation of Power Points from existing sources;- Teaching of Prisms; and- Commissioning (Commencement of Monitoring).

LAYOUT PLANSLAYOUT PLANSLAYOUT PLANSLAYOUT PLANSFor obtaining tilt and/or settlement information of viaduct beams/columns, the systemproposed is:Equipment Equipment Equipment Equipment2 nos. Total Station will be deployed to monitor the East and West Bound viaducts of MRTBuona Vista Station. 1 no. Total Station (STN1) will monitor the East Bound viaduct and 1no. Total Station (STN2) will monitor the West Bound viaduct. 1 no. Total Station will be on"standby" should any of the active Total Stations break down or require periodiccalibration mandated by the authorities.- Monitoring Prisms are to be installed at the following locations of both East Bound (EB) East Bound (EB)East Bound (EB)East Bound (EB)and West Bound (WB)and West Bound (WB)and West Bound (WB)and West Bound (WB) viaducts:(a) 2 nos. of prisms are to be installed at least 2m apart along the length of the viaductcolumn (ie, top and bottom);(b) 1 no. of prism is to be installed to the left and 1 no. of prism to the right of the flange ofthe column but before the expansion gap that separates the column and beam;(c) 1 no. of prism is to be installed at the soffit and on each end of the beam (i.e. left andright, 2 nos. of prisms per beam span); and(d) At least 18 nos. of reference prisms are to be installed outside the zone of influence(monitoring zone) per bound.- 2 nos. of prisms are to be installed one on each side of the station.- 1 no. of Electrolytic Sensor Beam is to be installed at the soffit and on each end of thebeam (ie, left and right, 2 nos. of ELS Beams per beam span) (please refer to Figure 1).

The viaduct columns (and the beam spans between them) to be monitored are referencedW157 E1 through W166 E1W157 E1 through W166 E1W157 E1 through W166 E1W157 E1 through W166 E1 (for East Bound viaduct) and W157 W1 through W166 W1W157 W1 through W166 W1W157 W1 through W166 W1W157 W1 through W166 W1 (forWest Bound viaduct).

The prism will be affixed to the surface of the beam and columns of the viaduct with theepoxy compound, "Devcon Plastic Steel Putty (A)" or its equivalent.

Epoxy


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ELS Beam and DataloggerELS Beam and DataloggerELS Beam and DataloggerELS Beam and DataloggerThe ELS Beam will be installed on the soffit of the viaduct beam as shown in theillustration below:


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1m length horizontalELS Beam

3mm nom. Thick 100 x100mm metal plating

Epoxy Applied Here

10mm nom.Diameterthreaded rod

Washer

10mm Nut

10mm

1. Installation of ELS Beam shall be done during Engineering Hours.2. Epoxy compound ("Devcon" et al) is applied on the side of the F-clamp (fixture) thatcomes in contact with the soffit of the viaduct beam;3. The F-clamp side is kept in contact with the soffit of the viaduct beam by tightening theadjustable threaded rod end to the side of the viaduct beam;4. The epoxy bond is allowed to cure for approximately twenty-four (24) hours;5. The ELS Beam is then installed;6. All cabling / wiring is neatly arranged and cable-tied to saddle hooks that have beenpreviously applied with epoxy in convenient locations on the viaduct;7. The ELS Beam is "balanced" horizontally using a handheld readout unit; and8. The ELS Beam is labeled to enable proper identification and input of the correctcalibration constants in the datalogger.

Access to the columns and beams to install the prisms and ELS beams in general will beby boom lift or its equivalent. In all situations, the boom lift will NOT NOTNOTNOT hoist past the soffit ofviaduct beam.

Fig 3: INSTALLATION OF ELS BEAM AND

Fig 4: RST INSTRUMENTS DATALOGGER


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POWER SUPPLYPOWER SUPPLYPOWER SUPPLYPOWER SUPPLYThe Total Stations STN1 and STN2 enclosed in the instrumentation protection huts willrequire 230V AC to power their respective computers and instruments. The ELS Beams


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and Datalogger run on DC power from a sealed battery that is stored on the dataloggerside. However, a 230V supply is recommended to power an adaptor (located in thedatalogger) that would continuously recharge the sealed battery. A stable existing powersource from the main contractor's facilities would be tapped and a Certified ElectricalLicensed Worker (LEW) would be engaged to carry out the necessary work. No powersupply shall be used from the Buona Vista MRT Station. If required, an endorsed linediagram shall be submitted for approval in the event when the actual connection point isdetermined on site with the relevant parties.

In the design of the system, an Uninterrupted Power Supply (UPS) is introduced as anadded precaution to prevent any fluctuation of power and sustain power duringtemporary shut down of mains. The UPS will supply backup power for up to 4 hour. Ifpower is disrupted by more than an hour, human intervention is necessary to reboot thesystem.

COMMISSIONING OF SYSTEM & MONITORINGCOMMISSIONING OF SYSTEM & MONITORINGCOMMISSIONING OF SYSTEM & MONITORINGCOMMISSIONING OF SYSTEM & MONITORINGWhen all the power, communications, total stations, prisms, ELS beams and dataloggerhave been installed, commissioning of the monitoring system is initiated. In thecommissioning stage, the total stations are "taught" to memorize each prism location bycoordinates. In this process, one round of manual survey will be carried out to transferthe known coordinates of each prism. The initial values are then keyed into the systemand the current data obtained (via the total station) is compared and verified. The initialreadings shall be based on the average of stabilized readings for the period of data. Thesystem is then ready for continuous monitoring.

MANUAL SURVEYMANUAL SURVEYMANUAL SURVEYMANUAL SURVEYThe Manual Survey will be carried out during the initial start-up of the system. It not onlyprovides co-ordinates but also acts as a check to the automated system. The automatedsystem relies very heavily on the stability of the reference prism and cannot function wellif any of the reference prisms are moving. Therefore stable positions are located forreference prisms. Manual Survey shall be carried out on a monthly interval thereafter orwhen confirming any irregularities.

Summary of SystemSummary of SystemSummary of SystemSummary of System

- The Monitoring frequency for the Automated Monitoring System is continuous with 4hours interval, 6 cycles per day continuously throughout the entire project. For the ELSBeams, the monitoring frequency is proposed to be at 2 hour intervals during the non-critical stages of the project, and 1 hour interval (as requested by the relevantauthorities) during the critical stages of the project. Refresh rate of ELS Beams is atevery 5 minutes.- The Manual Survey conducted by Registered Surveyor to supplement the AutomaticMonitoring System is to be carried out at the minimum interval of once monthly interval.The Total Station used for this purpose shall be calibrated at 6 month interval byaccredited calibration laboratory.- Submission of Geotechnical Database (GDB2) shall be e-mail at once daily.- Cleaning prisms whenever it is necessary.- Check of instrument level during maintenance trips (together with Manual Survey).


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Allowable Limits for C855 MRT ViaduAllowable Limits for C855 MRT ViaduAllowable Limits for C855 MRT ViaduAllowable Limits for C855 MRT Viaduc ccct & Column Monitoringt & Column Monitoringt & Column Monitoringt & Column Monitoring

S/NS/NS/NS/N DescriptionDescriptionDescriptionDescription WorkWorkWorkWorkSuspensionSuspensionSuspensionSuspension

AlertAlertAlertAlertLevelLevelLevelLevel(70%)(70%)(70%)(70%)

EngineeringEngineeringEngineeringEngineeringReviewReviewReviewReview(35%)(35%)(35%)(35%)

RemarkRemarkRemarkRemark

1 Total Movement InAny Direction 15mm 10.5mm 5.3mm GlassPrism

2DifferentialMovement in anyPlane

15mm or1:1000,whicheveris lesser

10.5mm or1:1428,whicheveris lesser

5.23mm or1:2857,

whichever islesser

GlassPrism

3 DifferentialMovement in Cant2mm or1:1000

1.5mm or1:1428

0.7 mm or 1:2857

E.L.Beam

4 Twist Change 1.5 mm 1.1 mm 0.55mm E.L.Beam

5 Vertical Dip orPeck 5.0mm 3.5 mm 1.75mm

6 Twist Change 15mm 10.5 mm 5.23mm


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PROJECT PHOTOGRAPHS


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Download - ADMS Project - Viaduct Monitoring

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