Method of determining mine roof stability

• US 4,318,302 A
• Filed: 12/13/1978
• Issued: 03/09/1982
• Est. Priority Date: 12/13/1978
• Status: Expired due to Term

• Current Assignee: Consolidation Capital Corp. (Residential Acquisition Co.)
• Original Assignee: Conoco Incorporated (ConocoPhillips)
• Inventors: Choi, Dai-Shik
• Primary Examiner(s): MYRACLE, JERRY
• Application Number:
  US05/969,079
• Time in Patent Office: 1,182 Days
• Field of Search: 73/582, 73/594, 73/761, 73/784, 73/581, 73/579
• US Class Current: 73/761
• CPC Class Codes: E21C 39/00 Devices for testing in situ the hardness or other properties of minerals, e.g. for giving information as to the selection of suitable mining tools
• CPC Class Codes: E21D 21/02 having means for indicating tension screwed connections specially modified for indicating tensile load F16B31/02
• CPC Class Codes: F16B 2031/022 using an ultrasonic transducer
• CPC Class Codes: G01L 1/255 using acoustic waves, or acoustic emission G01L1/10 and G01L1/16 take precedence
• CPC Class Codes: G01N 2291/02827 Elastic parameters, strength or force

Abstract

A method and apparatus for determining the tension of mine roof bolts and/or mine roof stability which utilizes the natural vibration frequency of the seated roof bolt and/or roof structure to provide indication of bolt tension and/or roof stability.

Claims

1. A method of testing mine roof stability, comprising the steps of:

exciting the mine roof bolt to vibration at the natural occurring frequencies by normal tightening of the roof bolt;

detecting the natural occurring frequency vibrations; and

analyzing spectrally to determine the predominance of frequency distribution within the range of natural occurring frequencies between zero and 1,000 Hz. to provide an indication of roof bolt tension thereby to derive an indicator of mine roof stability.