MAN-210 MEMS Bassett Convergence System
Contents
1. 19 Sample Installation Record eee eene nana nns 20 Sample Calibration SINS CU Xe ceo g RAE CE EXE RAN SEX RN AR YR DUAE EROS 21 2 Section 1 Introduction The Soil Instruments Bassett Convergence System BCS is designed to monitor and Oz displacements of structures and tunnels in near real time The BCS system can be used for Monitoring of tunnels to verify performance Monitoring deformation due to nearby construction activity Monitoring deformation in sprayed concrete tunnels under construction to ensure safety The BCS uses solid state servo accelerometers for measuring deformation These are highly resistant to electrical noise effects and mechanically very robust As such they are ideally suited to harsh environments such as tunnels and construction sites The sensors are used to monitor the position of reference pins installed into the structure to be monitored The sensors are linked to the pins via a system of low profile arms Spatial displacement of any pin changes the tilt of the arms connected to it and results in a changed sensor output The system can be used as a closed loop or left open ended With closed loops a Bowditch type correction can be applied to minimise the effects of errors Open ended systems are referenced to conventional surveys periodically unless one end is known to be stable or on2. Measure Tubing e Hold the first short arm perpendicular to the tunnel Point its long arm sensor at the next pivot pin At the same time hold the next long arm fitting the one mounted on the next pivot pin and point it back at the first pivot pin Measure the distance between the two long arm fittings The tubing should fit all the way into the fittings Allow extra length for the tubing if it is necessary to bend the tubing for clearance or to clear obstacles Bending and Cutting Tubing Bend tubing as required we recommend using a professional plumbers tube bending tool Hold tubing place and mark cut position cut tubing Check Length e Install long arm Fit the long arm into both long arm fittings Repeat for remaining arms Test for free movement then tighten screws Zeroing the sensors NOTE Before zeroing the sensor make sure that the sensor is mounted the right way up Once all the sensors are installed they require zeroing levelling Connect the sensor to a battery 8 16VDC using the red ve and black ve wires then measure the output voltage using a voltmeter The voltmeter should be set on its DC voltage range which covers 2 5 volts The white sensor wire goes to the red connector the green sensor wire goes to the black comm connector User Manual nnn Arm Alternatively use Soil Instruments IPI Readout Slacken the 3 Allen bolts holding the clamping ring
3. Short arm 9 Short arm 10 Long arm 1 Long arm 2 Long arm 3 Long arm 4 Long arm 5 Long arm 6 Long arm 7 Long arm 8 Long arm 9 Long arm 10 User Manual Appendix B Sample Calibration Sheet itmsoil Bell Lane Uckfield East Sussex t 44 0 1825 765044 e sales itmsoil com TN22 1QL United Kingdom f 44 0 1825 744398 w www itmsoil com itmsoil Holdings Ltd Registered in England Number 4239206 Registered Office Bell Lane Uckfield East Sussex TN22 1QL Sensor Type BCS Long Arm Sensor Date 01 Apr 2009 Model No 2176 143 02 Ambient Temp 20 0 C Range 2 Degrees Serial No BCS 5027 Calibration Rotary Table S N 21900871D Calibrated By J Kingshot Equipment S N Soil Equip No 1749 Calibrated Data 4 2000 000 1200 000 0 400 000 979 X01 0001 12200 1 X 0000 290 000 Conversion Factors b 0 004744 b 0 000272 b 0 014195 b 0 000813 bz 3 954273E 09 b 2 266075E 10 3 659975E 12 bs 1 823969E 13 b 6 307894E 16 3 614277E 17 b 1 591375E 19 bs 9 106232E 21 Conversion Formula Displacement Current Reading Initial Reading Reading b b X bX b X b X b X where X is the raw sensor data in mV The instrument detailed hereon has as applicable been tested and calibrated in accordance with procedures which are part of our I809001 20
4. and wire cutters for wiring The installation procedure is detailed below in the following steps Establish a direction of view Determine Sensor Spacing Install mounting brackets Install pivot pins Install long and short arms Install data logging system Test and zero sensors Document installation 3 01 Determine Linear Metreage of Tunnel and Sensor Spacing Before installing the Bassett Convergence System it is necessary to determine the linear metreage to be monitored and to set out the position of the system pivot pins which should be as equidistantly spaced as possible Calculate the linear metreage by multiplying the tunnel diameter by p 3 14 Calculate sensor spacing is the system closed or open If closed divide the linear radius by the number of sensor pairs then multiply by 2 If open measure the size of the gap typically the invert then use the following equations missing partof loop sin y r Where X is the gap invert and r is the tunnel radius subtract this from the linear radius and divide by the number of sensors to get the sensor spacing Note Remember you will need an addition end anchor for an open system 3 02 Direction of view It is necessary to establish a convention to relate the computer display to the actual installation The computer screen will look similar to the drawing below As Installed documentation must use the same direction of view Starting from the
5. used however if desired a voltmeter can be used An external 8 16VDC power supply will be needed to do this Whatever the datalogger or reading method the wiring remains the same The sensors are supplied with a polyurethane jacketed 4 core cable The cable has four conductors a foil screen and drain wire The drain wire and screen should be connected to the ground terminal at the sensor input terminals for maximum resistance to induced voltages and interference The sensor is a differential device and thus a and reading must taken The conductor colour codes are as per the table below Conductor Colour Identification Red Power 8 16VDC Black Ground White Sensor Signal High Green Signal Low Bare Wire Drain Screen Take extreme care whilst wiring to ensure conductors are correctly wired especially the red power conductor Always wire with the power switched off If it is desired to check the functioning of the sensors immediately after installation at zero degrees tilt i e true vertical or horizontal the sensor output is approximately 0 VDC When wiring into a datalogger it is good practice to wire the lowest sensor to the first channel the second sensor to the second channel etc If a program not supplied by Soil Instruments is being used the following protocol should be observed to obtain the best results Power sensors on wait for 3 seconds take a minimum of 50 readings differential voltage at minimum 1
6. 00 millisecond intervals and average 4 01 Install Data Logger Install data logger as close as possible to the BCS system to avoid long runs of signal cable e Cut off excess signal cable Do not loop excess signal cable under the logger This can cause interference from adjacent high voltage cables e Before connecting signal cable to the logger cut off dirty ends and strip insulation back to expose clean conductors e Wire the data logger as directed by the wiring diagram supplied with the logger A typical wiring diagram is shown in the following 12 User Manual OM ODD EVEN 4X16 LA H 11 2X32 Short 06 Long 06 Tun LES NN Lehe Me e e RT eleleleleleielisisisisielisieleisielelsielsielelsiellsijsisje NOTE For each sensor drain wire for screen or shield should be connected to L1 terminal on 16 32 User Manual 13 Section 5 Document Installation Use the installation record in Appendix A to document the sensors Items to document are Direction of view Sensor position Sensor serial number Sensor orientation use raw readings Zero reading Length of long arms 5 01 Pin Coordinates Obtain the coordinates of all fixed pivot pins using an optical survey In the example below you would provide coordinates for pivot pins A through J Alternatively you can measure distances from pin to pin as shown in the drawing below Measurements must be to the nearest mm You must al
7. 08 Quality Management System and unless otherwise indicated performs within 0 05 as specified Thus the in Certified By Line Manager soil INSTRUMENTS Bell Lane Uckfield East Sussex t 44 0 1825 765044 e info itmsoil com TN22 1QL United Kingdom f 44 0 1825 744398 w www itmsoil com Soil Instruments Ltd Registered in England Number 07960087 Registered Office 5th Floor 24 Old Bond Street London W1S 4AW 21 User Manual
8. 0X instructions below assume C1 Act multiplexer 1 C7 Act Switched 12Volt C8 CLK pulse for multiplexer Measuring channel is differential channel 1 Multiplexer CSI AM16 32 in 4x16 mode Set C8 for CLK pulse Activate multiplexer 1 on C1 1 Set Port s P20 1 4000 C8 C5 10ms low low low 2 0001 C4 C1 low low low high Start a loop for 16 BCS sensors 8 Short amp 8 Long Arms 2 Beginning of Loop P87 1 0000 Delay 2 16 Loop Count Send pulse 3 Do P86 1 78 Pulse Port 8 16 User Manual Activate SW12Volt 4 Do P86 1 47 Set Port 7 High Let the sensors warm up for at least 3 seconds 5 Excitation with Delay P22 3 Ex Channel 0000 Delay W Ex 0 01 sec units 300 Delay After Ex 0 01 sec units 0 mV Excitation KR 0 Ne Start a loop for 50 measurements 6 Beginning of Loop P87 1 0000 Delay 2 50 Loop Count Measure the sensors differential on channel 1 7 Volt Diff P2 1 1 Reps 225 2500 mV Slow Range 354 DIFF Channel 4 2 Loc measmV 01 5 1 0 Multiplier 6 0 0 Offset 8 End P95 De Activate the SW12Volt 9 Do P86 1 57 Set Port 7 Low Take the Average of the measurements and store it 10 Spatial Average P51 1 50 Swath 2 2 First Loc measmV 01 3 1 Avg Loc BCSmV 01 of Loop 11 End P95 De Activate multiplexer 1 12 Do P86 I 51 Set Port 1 Low If in any doubt we recommend contacting Soil Ins
9. ation of calibration factors and gauge length is fully automatic The MEMS Accelerometer chip used in the BCS sensor is calibrated for temperature as part of the micro machine manufacturing process by the chip manufacturer As well as the MEMS tilt element the sensor contains a microprocessor and a look up table to apply correction for temperature changes to the silicon substrate within the sensing element Soil Instruments has no control over this process other than by the QA procedures followed by the chip manufacturer which specify the correction and rejection criteria The sensor output is therefore corrected automatically for the effects of temperature on the accelerometer chip Please note that this correction will not apply to unknown factors within the sensor string or borehole where an external change may well be occurring Soil Instruments do not offer the sensor with an on board temperature sensor If temperature measurement is desired then a separate temperature sensor must be installed additional to the BCS sensor 18 User Manual Section 8 Calibration Calibration frequency of Instrumentation is generally dictated by contract or regulation requirements Additional guidelines can be offered by the manufacturer if needed For Instruments that are not installed in fixed positions ie portable or are not required for continuous monitoring the manufacturer would advise that where possible annual calibration is recommended Regular ca
10. libration of portable instrumentation is essential as the instruments are more exposed to various influences Manufacturer guidelines are intended to be guidelines only many factors might influence the calibration frequency decision Some of these factors might be usage system performance indicators and environmental effects The users should conclude the calibration requirement based on all factors presented Instrumentation that is installed for long term monitoring of structures should be calibrated pre installation Following installation further calibration periods should be decided based on monitoring requirements and system performance Commonly due to instrumentation being installed in an environment where it remains untouched calibration periods might be further apart Typically instruments are not recalibrated during long term monitoring of a structure unless results have raised concern and there is call for the instruments to be verified 19 User Manual Appendix A Sample Installation Record Sheet Project Title Date of Installation Direction of View Project Engineer Sensor Serial Number Rotate Sensor clockwise Does Zero reading Arm length the reading increase or decrease Mark the appropriate column straight line distance from pin to pin mm Short arm 1 Short arm 2 Short arm 3 Short arm 4 Short arm 5 Short arm 6 Short arm 7 Short arm 8
11. lower left side label the monitored positions A B C D etc as shown below User Manual Two sensors will be installed for each monitored point a short arm sensor and a long arm sensor Starting from the lower left label the sensors short No 1 amp long No 1 short No 2 amp long No 2 etc as shown below NOTE A closed system is shown An open system would omit long arm No 10 and short arm 10 3 03 Install Mounting Brackets Mark locations for mounting brackets so that the plane of Bassett section will be perpendicular to the structure Using a tape or a laser level pick a point at the centre of the crown or invert and mark out from there Groutable Anchor or other Fixing Mounting Bracket Pivot Pin User Manual 3 04 Install Pivot Pins Fit a pivot pin to each mounting bracket Pivot pins should all point the same way 3 05 Install Short Arms Sensors The short arm sensor should be installed at an angle of between 70 and 110 to the tunnel surface Long Arm Sensor M o Long arm Start at the bottom pivot pin on one side Do not work from both sides at once Continue mounting short arms until you reach the last pivot pin 3 06 Install Long Arms Long arms are made from stainless steel tubing which you must measure shape to fit and cut Start at the bottom left and work your way around to the last pivot pin on the right i e the direction of view User Manual
12. ly relative deformation are required User Manual Section 2 Identify Components An installed BCS consists of the following from left to right Mounting Bracket Pivot Pin Short Arm amp Sensor 1 Long Arm Sensor 1 Long Arm Coupler Long Arm Threaded Yoke Mounting Bracket Pivot Pin Short Arm amp Sensor 2 Long Arm Sensor 2 Long Arm Coupler Long Arm Threaded Yoke Repeat for the number of sensor pairs in the system Note Final Mounting Bracket is required if the system is to be installed as an open loop Not required for closed loop User Manual Basset Convergence System Components WARNING Removal or adjustment of this screw will invalidate sensor warranty Long Arm Coupler NB mount sensor screw upwards Long Arm Sensor Long Arm Sensor Clamping Ring 7 Allen Bolts Mounting Bracket Cable Gland Groutable Anchor or other fixing into structure Short Arm amp Sensor Threaded Yoke Pivot Pin amp Clip Long Arm User Manual Section 3 Installation This manual covers the installation of the BCS it does not cover the attachment of the mounting method bracket This fixing method will depend on the tunnel type and construction The following tools are required for installation 2 No Adjustable spanners or 16mm 17mm 24mm 27mm and 30 5mm spanners Allen key Hacksaw to cut long arms to fit 10 metre tape measure Small flat blade screwdriver
13. scil INSTRUMENTS Bassett Convergence System BCS User Manual Man210 1 0 3 07 08 2014 Final David Farnham Phil Day Manual No Revision Date Originator Checked Authorised for Issue User Manual Contents Section 1 Section 2 Section 3 3 01 3 02 3 03 3 04 3 05 3 06 3 07 Section 4 4 01 Section 5 5 01 Section 6 Section 7 Section 8 Appendix A Appendix B User Manual i giugerelllotdloro a a M 3 Identify COMPONENTS E CER EDS NV ME a ITE E ROSE 4 installato D a FR VR T FE PN a Hw Ra 6 Determine Linear Metreage of Tunnel and Sensor 6 DIFecton Gals avons us M ce Deans Lot epa e tour deus Dol gene pv D deo 6 Install Mo ntindg Brackets is NO ERI a ON ERU 7 acis uiaduncm tc c Ucet 8 Irnistall Snort Sensol S buts vivet d uode E fos CENE DUE 8 Stal LONG RR Ee 8 Dressing the Cable EM 11 WID O oiueon etude ceuttu pe te vulc uma oed acuc iue Vau Via tun Usa C ceu 12 Install Data 12 Document Fui Pana ERRSEVNE Ir Qe VIP VN Fa PREEHE VERE FFV TIR WI VERRE 14 PN COOl GIMACES OTT TT TEE 14 Taking Readings Logger Programming 16 FROG CUNO i een 18 e lblp isl me
14. so provide the x and y distances between pins A and B as shown in the drawing User Manual Distances Between Reference Pins to nearest millimeter User Manual Section 6 Taking Readings Logger Programming The Soil Instruments BCS sensors are designed to be read by Campbell datalogger systems Other data loggers can be used but the basic reading and excitation architecture outlined in this section must be followed Sensors should be read via a multiplexer Campbell AM416 or AM16 32 and the following sequence must be used to ensure best sensor performance Activate multiplexer Switch to first channel 1 Switch on power supply to sensor Campbell loggers use the Switched 12Volt option Let the sensor warm up for at least 3 seconds Take a minimum of 50 differential measurements and store the average Switch power to the sensor off Switch to the next channel MI Repeat step a through for the next sensor De activate multiplexer NOTE a sample program for a CSI CR10X unit is printed below for CR800 and CR1000 programs please contact Soil Instruments Sensors can be left powered when not being read but for maximum life we do not recommend this When using multiplexer units this is not possible and the above sequence should be observed When long cables are used make sure to increase the settling time for the datalogger measurements to achieve optimal performance These sample CR1
15. to the sensor arm Only slacken as much as required to be able to turn the sensor with some resistance If the sensor is too lose when tightening the bolts the sensor will move too much 10 User Manual Slacken Allen Bolts Clamping Ring Adjust by rotating sensor housing until level 0 1 volts When viewed from the cable entry Side as above an anti clockwise rotation will cause a positive change in the mV reading Carefully tighten the bolts ensuring the sensor doesn t move It is advisable to leave the readout connected during tightening 3 07 Dressing the Cable Starting at the end furthest from the data logger location dress the cables around the BCS e Allow slack in the cable for strain relief where it passes sensors This will be needed when the arms move e If possible fix cable to tunnel lining rather than to the arms e Avoid crossing pivot points Make a loop in the cable to avoid moving parts 11 User Manual Section 4 Wiring The Soil Instruments BCS can be read by most commercially available data loggers Soil Instruments recommend the Campbell datalogger range and can supply a fully built up datalogger with enclosure logging program and a variety of communications options from a simple direct link to satellite modem please see our datalogger datasheets We do not recommend that BCS is read with a manual readout as this defeats the objective of the BCS where a traditional tape extensometer could be
16. truments for advice The performance of the sensors as calibrated is not guaranteed unless the above protocols are used Soil Instruments can supply full logger programs and wiring diagrams at an extra cost please contact us for details 17 User Manual Section 7 Data Reduction The Soil Instruments BCS sensor is calibrated over 2 arc degrees long arm or 10 arc degrees short arm approx 35 or 175mm metre and has a DC voltage output dependant on tilt The sensors are calibrated for tilt only please see note on temperature below and the unit of calibration either Arc Degrees or mm metre is specified at the time of order The calibration certificate supplied with the sensor please see section 6 contains the following information Instrument Type Serial Number Range Calibration Data both raw and reduced Conversion Formula FS Error at each calibration point Wiring Code Note Once the polynomial formula has been calculated the resultant must be multiplied by the gauge length of the sensor measured during installation to give correct cumulative deflection calculations unless only individual arc degree rotations are required A positive resultant indicates anti clockwise rotation mm a negative resultant indicates clockwise rotation mm The calibration factors can easily be loaded into a spreadsheet and data added via cut and past or an automated program such as Argus can be used in which case the applic
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