Measuring mine roof bolt strains

Patent · Wed Jan 01 00:00:00 EST 1986

OSTI ID:865930

Steblay, Bernard J ^[1]

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1. Lakewood, CO

A mine roof bolt and a method of measuring the strain in mine roof bolts of this type are disclosed. According to the method, a flat portion on the head of the mine roof bolt is first machined. Next, a hole is drilled radially through the bolt at a predetermined distance from the bolt head. After installation of the mine roof bolt and loading, the strain of the mine roof bolt is measured by generating an ultrasonic pulse at the flat portion. The time of travel of the ultrasonic pulse reflected from the hole is measured. This time of travel is a function of the distance from the flat portion to the hole and increases as the bolt is loaded. Consequently, the time measurement is correlated to the strain in the bolt. Compensation for various factors affecting the travel time are also provided.

• Research Organization: National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States)
• Assignee: United States of America as represented by Secretary of (Washington, DC)
• Patent Number(s): US 4601207
• OSTI ID: 865930
• Country of Publication: United States
• Language: English

Related Subjects

measuring
mine
roof
bolt
strains
method
strain
bolts
type
disclosed
according
flat
portion
head
machined
drilled
radially
predetermined
distance
installation
loading
measured
generating
ultrasonic
pulse
time
travel
reflected
function
increases
loaded
consequently
measurement
correlated
compensation
various
factors
affecting
provided
mine roof
ultrasonic pulse
predetermined distance
roof bolt
flat portion
travel time
roof bolts
pulse reflected
time measurement
/73/405/