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Geokon 4910 Instruction Manual

Instrumented rockbolt
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Instruction Manual
Model 4910
Instrumented Rockbolt
No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon
®
.
The information contained herein is believed to be accurate and reliable. However, Geokon
®
assumes no responsibility for errors,
omissions or misinterpretation. The information herein is subject to change without notification.
Copyright © 2007-2019 by Geokon
®
(
Doc Rev B, 05/02/19)

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Summary of Contents for Geokon 4910

  • Page 1 Instruction Manual Model 4910 Instrumented Rockbolt No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon ® The information contained herein is believed to be accurate and reliable. However, Geokon ® assumes no responsibility for errors, omissions or misinterpretation.
  • Page 3 Geokon or any breach of any warranty by Geokon shall not exceed the purchase price paid by the purchaser to Geokon for the unit or units, or equipment directly affected by such breach. Under no circumstances will Geokon reimburse the claimant for loss incurred in removing and/or reinstalling equipment.

  • Page 5: Table Of Contents

    TABLE of CONTENTS Instruction Manual............................... 1 4910 ................................. 1 ODEL INSTRUMENTED ROCKBOLT ..........................1 1. INTRODUCTION ..............................1 1.1 T ............................1 HEORY OF PERATION 2. INSTALLATION ..............................3 2.1 P ............................3 RELIMINARY ESTS 2.2 I ......................3 NSTRUMENTED...
  • Page 6 FIGURES 1 - T 4910 R GK-404 R ..............1 IGURE EADOUT ROBE USED WITH THE EADOUT 2 - M 4910 I ........................2 IGURE ODEL NSTALLATION 3 - L GK-404 ........................4 IGURE ONNECTOR TO 4 - L –...

  • Page 7: Instruction Manual

    1. INTRODUCTION 1.1 Theory of Operation The Geokon Model 4910 Instrumented Rockbolt is made by inserting a vibrating wire strain gauge inside a short length of standard threaded rockbolt or rebar. This short length is then connected to a longer length of the same bolt material by means of a coupler. The full rockbolt assembly is then installed in the normal manner, making sure that the strain gauged portion of the bolt remains located in the loaded section of the bolt.

  • Page 8: Figure 2 - Model 4910 I

    Figure 2 - Model 4910 Installation...

  • Page 9: Installation

    2. INSTALLATION 2.1 Preliminary Tests Before installing the Instrumented Rockbolt, it should be checked by connecting it to the readout box and taking a no-load reading. This reading, when compared with that given in the calibration data provided with the load cell, will show if the sensor is functioning properly. The two readings should agree within about ±50 digits.

  • Page 10: Taking Readings

    20 hours on two AA batteries. It is designed for the readout of all Geokon vibrating wire gauges and transducers; and is capable of displaying the reading in either digits, frequency (Hz), period (µs), or microstrain (µε).

  • Page 11: Gk-405 Readout Box

    Connecting sensors with bare leads: Attach the GK-403-2 flying leads to the bare leads of a Geokon vibrating wire sensor by connecting each of the clips on the leads to the matching colors of the sensor conductors, with blue representing the shield (bare).

  • Page 12: Gk-403 Readout Box (Obsolete Model)

    Connecting Sensors with Bare Leads: Attach the GK-403-2 flying leads to the bare leads of a Geokon vibrating wire sensor by connecting each of the clips on the leads to the matching colors of the sensor conductors, with blue representing the shield (bare).

  • Page 13: Data Reduction

    4. DATA REDUCTION 4.1 Load Calculation he basic units utilized by Geokon for measurement and reduction of data from Instrumented Rockbolts are "digits". Calculation of digits is based on the following equation: Digits = � � x 10 or Digits=...

  • Page 14: Temperature Correction Factor

    Note that the equations assume a linear relationship between load and gauge readings over the full load range, and the linear coefficient is obtained using regression techniques. Note that when using the Calibration Factor obtained from the regression formula it is better to use the regression zero.

  • Page 15: Troubleshooting

    5. TROUBLESHOOTING Problems with the instrumented rockbolt are usually associated with dirty electrodes. Symptom: Instrumented Rockbolt Readings are Unstable:  Is the readout box position set correctly? (Use Channel B.)  Does the readout work with another instrumented rockbolt? If not, the readout may have a low battery or be malfunctioning.

  • Page 16: Appendix A. Specifications

    −40 to +80° C -40 to 110° F Frequency Output Range 1400-3000 Hz Over-range: 150% Bolt Size 25 mm or #8 rebar and larger. Length 300 mm (standard) (other lengths are optional) Table 2 - Model 4910 Instrumented Rockbolt Specifications.

  • Page 17: Appendix B. Sample Calibration Report

    APPENDIX B. SAMPLE CALIBRATION REPORT Figure 5 - Typical Model 4910 Calibration Report...

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