Portable Bore-Hole Shear Strength Tester for Coal.

摘要

The objective of the research was to devise and test an apparatus to rapidly evaluate the cohesive and frictional strength of coal in situ,in order to increase the safety and percentage of coal recovery from underground coal mines. Since it is extremely difficult to obtain large samples of coal for laboratory testing,the borehole shear tester promises to be of significant value to mining engineers and researchers in determining the physical properties of coal and related strata. Such physical properties are essential to the use of finite-element analyses or other techniques of mine design. During the first year a device was designed using the bore-hole shear test principle from soil shear strength testing. Two opposing corrugated plates were forced outward to exert a controlled contact pressure against the sides of a previously bored hole,and then the plates were slowly pulled along the axis of the hole to cause shearing of coal in contact with the plates.