Vibrating Wire Crackmeter User Manual
Contents
1. and thermistor if included during the preliminary test and after the installation as well as the sensor serial number and its location Please refer to Part Ill Appendices Appendix A Installation Record Sheet Example in this manual for details Wiring Identification SPLICING THE CABLE The four wires from the crackmeter are identified in the table below n ne i ona Red Crackmeter sensor l Black Cackmetersensor Green Themistor White SSS Thenmistor Shield mid Because Vibrating Wire transducers output frequency or period a direct derivative of frequency rather than current or voltage slight variations in cable resistance have no detrimental effect on the readings Consequently splicing has no effect on instrument performance allowing cables to be spliced and routed to junction boxes and then connected to multi conductor cables for transmission to a central location 15 Part Il Data Reduction amp Temperature Correction Contents This section contains the following topics TOPIC SEE PAGE Calculation of Engineering Units From Frequency Based Units Calculation Using Period Units Calculation Using Linear Units 18 Calculation of Engineering Units From Frequency Based Units OVERVIEW CALCULATION USING PERIOD UNITS The mathematical relationship between the frequency of vibration of a tensioned wire and the force applying the tension is an approximate str2. damaging the Vibrating Wire element The rod is connected directly to the wire via the spring therefore the rod should not be rotated or extended beyond the range of the instrument at any point during the installation process as this will cause damage to the Vibrating Wire element Unpack the Vibrating Wire Crackmeter and familiarise yourself with the product e Connect the wires from the crackmeter cable to a readout unit e Pull the connecting rod out to approximately 3mm e Check that the reading is stable for the crackmeter and thermistor if included e Record the reading for the crackmeter and thermistor if included For further information on Vibrating Wire readouts please refer to datasheets RO 1 VW NOTE Vibrating Wire Note and RO 1 VW READ Vibrating Wire Readout which can be downloaded from either our website www itmsoil com or our support site www itmsoilsupport com You must perform the preliminary test on each sensor before you install it 11 12 INSTALLING THE SENSOR Soil Instruments recommend an intermediate skill level for installing a Vibrating Wire Crackmeter The crackmeter may be installed with groutable or expanding shell anchors To allow for compression of the crack to be monitored it is recommended that the sensor is installed with 25 of the available range of the instrument reserved for compression and 75 available for extension When you have established the installed
3. 9 986 0 01 30 00 4007 4 6226 9 29 870 0 13 556 3 29 847 0 15 40 00 3832 9 6806 9 40 172 0 17 580 0 40 137 0 14 50 00 3685 2 7363 5 50 058 0 06 556 6 50 019 0 02 60 00 3551 8 7926 9 60 064 0 06 563 4 60 029 0 03 70 00 3432 7 8486 3 70 000 0 00 559 4 69 976 0 02 80 00 3324 6 9047 3 79 964 0 04 561 0 79 960 0 04 90 00 3225 9 9609 3 89 945 0 05 562 0 89 969 0 03 100 00 3135 1 10174 3 99 980 0 02 565 0 100 039 0 04 Formulae Linear E G RO R1 Polynomial E ARI BRI C The zero reading should be established on site by the user on installation The site value of C must be calculated using the formula C AR0 BRO The instrument detailed hereon has as applicable been tested and calibrated in accordance with procedures which are part of our ISO 9001 2008 Quality Management System and unless otherwise indicated performs within 0 20 Polynomial as specified Thus the instrument conforms in all respects to our relevant specifications and drawings Certifiedi 11 12 0000 cricca rici essences Line MANAGER 27 SUPPORT www itmsoilsupport com 44 0 1825 765044 Soil INSTRUMENTS Bell Lane Uckfield East Sussex t 0 1825 765044 e info itmsoil com TN22 1QL United Kingdom ip 0 1825 744398 w www itmsoil com
4. Man 117 Sell Vibrating Wire Crackmeter User Manual n Safe PIP ry ft ft land dol imk nd sr td ne Tr emperor YP PAAA IA Ny POLTI pr PI ta Soil Instruments Limited has an ongoing policy of design review and reserves the right to amend these specifications without notice Man117 Vibrating Wire Crackmeter MN0814 Rev1 0 1 What s this manual about This manual tells you about the Vibrating Wire Crackmeter and how to use it to monitor crack displacement Who does this apply to Installers field engineers and technicians who need to measure crack displacement using a Vibrating Wire Crackmeter Welcome Thank you for choosing the Vibrating Wire Crackmeter This manual has been written to provide you with relevant information and to guide you in best practice when using a Vibrating Wire Crackmeter in order for you to gain the most from our product Please read this manual thoroughly before use to help avoid any problems and keep it handy when using a Vibrating Wire Crackmeter Vibrating Wire Crackmeter The Vibrating Wire Crackmeter provides accurate measurement of crack propagation for structural or geotechnical monitoring The sensor is made from high quality Stainless Steel incorporates O ring seals to allow for underwater use and is designed for long term reliable monitoring Fitted across a crack or joint the sensor monitors displacement by detecting a change in tension
5. aight line relationship between the square of the measured frequency and the applied force Engineering units of measurement maybe derived from the frequency based units measured by vibrating wire readouts in three traditional ways From period units t x 107 and from linear f42 1000 units using two methods a simple linear equation or a polynomial equation The following formula is used for readings in period units E K 1047 POA2 1047 P 142 Where E is the pressure in resultant engineering units K is the period gauge factor for units of calibration from the calibration sheet PO is the installation period base or zero reading P1 is the current period reading This method of calculation is used by Soil Instruments Vibrating Wire oggers models RO 1 VW and with serial numbers starting VL or TVL internal processors for calculating and displaying directly on the oggers LCD screen the required engineering based units The loggers require period base or zero reading units for entering into their channel tables to calculate and display correctly the required engineering units f an engineering based unit is required other than the units of calibration then the correct K factor will have to be calculated using the standard relationship between engineering units For example if the units of engine
6. anual for details on the method required for verifying signal strength Please refer to Datasheets RO 1 VW NOTE Vibrating Wire Note and RO 1 VW READ Vibrating Wire Readout for details on Soil Instruments Vibrating Wire handheld readouts Wildly fluctuating readings from the sensor or an unsteady audio signal are both indications of possible problems with the instrument or related electrical cables If the readout is giving faulty readings or audio signals from all of the crackmeters a faulty readout unit and or lead must be suspected Another lead readout unit should be used to check the readings If there is a fault with the readout unit please contact www itmsoilsupport com for assistance ACTION The resistance across the two conductors of the electrical cable i should be tested using a multimeter Check the resistance across i the two conductors either at the end of the cable if available or at the corresponding terminals if wired into a Datalogger i The resistance across the two conductors should be approximately i 1200to 1800 The majority of this resistance will come from the i crackmeter approximately 1300 with the remainder from the i electrical cable connected to the transducer for 22 gauge copper resistance is approximately 10 15m i Before proceeding the continuity should be checked between i conductors and the earthing screen of the electrical cable continuity exists a damaged cable is confirme
7. d 25 Appendix B Troubleshooting Guide Continued STEP ACTION i If the resistance across the two conductors is much higher than i the values quoted in STEP 1 or is infinite a severed cable must i be suspected i If the location of the cable damage is found the cable can be i spliced in accordance with recommended procedure i If the resistance across the two conductors is much lower than i the values quoted in STEP 1 less than 80 O it is likely that cable i damage has occurred causing a short in the circuit i It is possible to calculate approximately how far from the cable end 3 i or readout location the suspected fault is If the resistance of a i known length of conducting cable is measured a resistance length i unit can be found This figure can be used to calculate the length of i the conductor cable in between the readout location and the break in the circuit If the location of the cable damage is found the cable i can be spliced in accordance with recommended procedure This method is only applicable if the short occurs between the two conductors of the electrical cable Since cables are generally buried or hidden it is may not be possible to confirm a short is of this nature using this method ACTION If the resistance is within the values quoted in STEP 1 and no i continuity exists between the conductor and the earth screen i AND the reading from the crackmeter is unstable or wi
8. d at the installation time as follows C AROA2 BRO Where A and B are as above RO is the installation linear base or zero reading Please note that the sign of the re calculated value of C should be the same as the original value of C so if the original is negative then the re calculated value should also be negative Conversion to engineering units other than the units of calibration would best be done after conversion using a factor calculated using the same principles as stated in the Calculation Using Period Units section 19 20 Temperature Correction The Vibrating Wire Crackmeter working elements are made primarily of steel and Stainless Steel and are affected by changing temperature to a certain predictable degree In case of large temperature changes application of temperature correction will improve the accuracy of the measurements The approximate temperature effect on the gauge is 0 02mm per C therefore a temperature increase of 10 C will indicate 0 02mm x 10 0 2mm to the result indicated by the crackmeter reading A fall in temperature will result in a positive change in linear measurement which can be corrected accordingly Barometric pressure changes do not affect the crackmeter reading ENVIRONMENTAL FACTORS Since the purpose of the crackmeter installation is to monitor site conditions factors which may affect these conditions s
9. distance between the anchors which is the length of the crackmeter measured between the centres of the universal joints plus 25 of the range of the instrument a drill template can be made to make multiple installations quicker and easier ACTION i Measure the length of the crackmeter from the centres of the universal joint sockets i Add 25 of the range of the instrument to the length of the i crackmeter measurement Mark out the locations for drilling at either side of the crack with the crack central using the determined measurement i Measure the depth of the chosen anchors to establish the i depth of the hole to be drilled Once you have measured the correct depth for the anchors mark the drill bit with insulation tape to avoid drilling the holes to deep shallow and to save time on multiple installations If you are installing the crackmeter over a segment joint or an uneven surface you may need to offset the anchors to ensure the crackmeter has suitable clearance STEP ACTION i Drillthe holes to the required depth and extract the dust from the holes Remove the wire clips from the universal joints at each end of the 6 i crackmeter and remove the balls from the sockets of the joints i i making sure the wire clips are retained in a safe place for re assembly Remove the wire clip by rotating the loop over the joint and withdrawing STEP ACTION i Place the anchors into the holes using t
10. e repeatable readings over long cable lengths e Long working life e Long term stability and reliability e Connecting cable is strong screened and flexible 10 System Components OVERVIEW The Vibrating Wire Crackmeter consists of a telescoping sensor body incorporating a sprung tensioned Vibrating Wire element Each end of the telescoping body is anchored either side of the crack to be monitored A change in distance between the anchors by the crack opening or closing will cause the connecting rod to move within the transducer body changing the tension on the spring and thus altering the resonant frequency of the wire Vibrating Wire Crackmeter Components Transducer body Connecting rod Wire clip Locking pin Wire clip mso o 1 Universal joint Groutable anchors Follow the precautions outlined in this manual at all times to ensure the correct working order of your instrument Quick Guide to Using the Vibrating Wire Crackmeter PRELIMINARY TEST Soil Instruments recommend an intermediate skill level for installing a Vibrating Wire Crackmeter It is essential that the equipment covered by this manual is handled operated and maintained by competent and suitably qualified personnel The connecting rod must be withdrawn and re inserted into the body in a controlled manner as withdrawing and releasing the rod will result in it returning into the body at speed and
11. ering required were in inches and the calibration units were millimetres mm we we can conclude that 1mm is equal to 0 03937 f so we would derive the K factor for inches by multiplying the K factor for millimetres by 0 03937 A negative sign represents a decrease in length across the crackmeter anchor points CALCULATION USING LINEAR UNITS LINEAR UNIT CALCULATION USING A POLYNOMIAL EQUATION The following formula is used for readings in linear units E G RO R1 Where E is the resultant engineering unit G the linear gauge factor for the units of calibration from the calibration sheet RO is the installation linear base or zero reading R1 is the current linear reading The linear gauge factor for units other than the units of calibration would need to be calculated using the same principles as stated in the Calculation Using Period Units section Linear units may be applied to the following polynomial equation for calculation of engineering units to a higher order of accuracy E AR142 BR1 C Where E is the resultant engineering unit A B and C the polynomial gauge factors from the calibration sheet R1 is the current linear reading The value C is an offset value and relates to the zero value experienced by the transducer at the time of calibration This value should be re calculate
12. he appropriate method for the chosen anchors For groutable anchors fill the holes with grout or resin and push the anchors in place and allow to set For expanding shell anchors push the anchors into the holes and expand by tightening the anchor bolt The connecting rod must be withdrawn and re inserted into the body in a controlled manner as withdrawing and releasing the rod will result in it returning into the body at speed and damaging the Vibrating Wire element STEF ACTION i Refit the crackmeter to the ball joints on the anchors by attaching the 9 i cable end of the instrument first and re inserting the clip followed by i the opposite end Push the socket at the cable end of the crackmeter over the ball on the anchor and re insert the clip through the holes on the side of the joint socket then rotate the loop over the joint into its original position Withdraw the rod end and position over the ball on the second anchor and hold in place until the clip has been re fitted EE k O ail Record the reading of the crackmeter and thermistor if included 10 and the sensor serial number and retain in a safe place as the base i zero reading of the instrument for data interpretation Please refer to Datasheets RO 1 VW NOTE Vibrating Wire Note and RO 1 VW READ Vibrating Wire Readout for details on Soil Instruments Vibrating Wire handheld readouts Make sure you record the readings from each crackmeter
13. hould always be observed and recorded Seemingly minor effects may have a real influence on the behaviour of the structure being monitored and may give an early indication of potential problems Such factors include but are not limited to e Blasting e Rainfall e Tidal levels e Excavation fill levels and sequences e Site traffic e Temperature and barometric changes e Changes in personnel reading the instruments e Nearby construction activities e Seasonal changes 21 Part Ill Appendices Contents This section contains the following topics TOPIC SEE PAGE Appendix A Installation Record Sheet Example Installer name i John Smith Site name Example Site Calcert Preliminary i Installed Reading Sensor i match i test i sa i 25 range i from serial i i Date i Location Date i Date q er ee serial reading i reading i datalogger ST number F2 1000 i i F2 1000 i F2 1000 Appendix B Troubleshooting Guide STEP Before any of the steps below are followed a Vibrating Wire readout unit should be used to verify the stability of the reading The method used to verify the signal will be dependent on which type of VW readout is being used all Soil Instruments readouts use FFT analysis where as some other manufacturers use audio signal Please refer to the manufacturers user m
14. in the Vibrating Wire inside the sensor The Vibrating Wire Crackmeter provides accurate repeatable readings over long cable lengths combined with a long working life and long term stability and reliability Contents PART GENERAL USER GUIDE Introduction Important Information Product Changes Warranty Disposal System Description Things You Need to Know About the Vibrating Wire Crackmeter Features Benefits System Components Overview Vibrating Wire Crackmeter Components Quick Guide to Using the Vibrating Wire Crackmeter Preliminary Test nstalling the Sensor Wiring Identification Splicing the Cable PART Il DATA REDUCTION amp TEMPERATURE CORRECTION Calculation of Engineering Units From Frequency Based Units Overview Calculation Using Period Units Calculation Using Linear Units Linear Unit Calculation Using a Polynomial Equation Temperature Correction Environmental Factors PART III APPENDICES Appendix A Installation Record Sheet Example Appendix B Troubleshooting Guide Appendix C Calibration Sheet Example O O O 0 0 0 0 0 0 0 A Om KG 0 Sy EN 1S o 02 00 OW A 20 22 24 DS DI PRECISELY MEASURED instrumentation and monitoring Part General User Guide Contents This section contains the following topics TOPIC ___SEE PAGE Disposal em Description Preliminary Test nstalling the Sensor Introduction Important Information The followi
15. ldly i fluctuating it must be assumed that the integrity of the circuit i is good and the fault lies within the crackmeter In this case i please contact our support team at itmsoilsupport com Appendix C Calibration Sheet Example F itmsoil BS EN ISO 9001 2008 FM 553710 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 group itd Registered in England Number 4239206 Registered Office Bell Lane Uckfield East Sussex TN22 1QL VIBRATING WIRE INSTRUMENTS CALIBRATION CERTIFICATE Instrument Type J2 Vibrating Wire Crack Meter Serial No 1 049836 Instrument Range 0 00 to 100 0 mm Calibration Date 1 23 12 2013 Gauge Factors in mm Ambient Temperature 322 C Period Gauge Factor K 177 6106000 Barometric Pressure 1003 mbar Linear Gauge Factor G mm digit 0 0177600 Calibration Technician Mark Lintott Polynomial Gauge Factor A 0 000000012298030 lalibration Equipment Digital Micrometer Scale Polynomial Gauge Factor B 0 0175800900 Vibrating Wire Data Recorder DR216 Polynomial Gauge Factor C 80 099120 Regression Zero 1 4545 1 Applied Reading Reading Calculated Error FS Linear Calculated Error FS mm Period F 1000 Linear Linear Increment Polynomial Polynomial 0 00 4692 5 4541 5 0 064 0 06 0 0 0 006 0 01 10 00 4424 0 5109 3 10 021 0 02 567 8 10 044 0 04 20 00 4199 4 5670 6 19 990 0 01 561 3 1
16. ng symbols are used throughout the manual IMPORTANT INFORMATION PRODUCT CHANGES WARRANTY DISPOSAL OV AD QUESTION WARNING Important Failure to adhere to the warnings in this manual may result in network disruption and possible data loss Failure to observe the warning may result in injury product malfunction unexpected readings or damage to the product that may invalidate its warranty Tips give additional information that may be helpful when using a Vibrating Wire Crackmeter Soil Instruments has an on going policy of design review and reserves the right to amend the design of their product and this instruction manual without notice Refer to our terms and conditions of sale for warranty information The batteries are a consumable item and are excluded from the warranty Products marked with the gum symbol are subject to the following disposal rules in European countries e This product is designated for separate collection at an appropriate collection point e Do not dispose of as household waste e For more information contact Soil Instruments or the local authority in charge of waste management System Description Things You Need to Know About the Vibrating Wire Crackmeter FEATURES e Uses proven Vibrating Wire technology e Ideal for long term monitoring e Suitable for manual or remote monitoring e Fully waterproof e Fitted with thermistor for temperature monitoring BENEFITS e Accurat
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