A diamond drill hole (76 mm outer diameter) is drilled to wanted depth. The core is remove
and the hole bottom is flattened with a special drill bit.
IS Inserted mto the hole vwth a special mstallmg tool and glued to the bottom of the hole
i A two dimensional measuring cell (doorstopper) that contains a strain gauge rosette, ‘
The doorstopper is now fixed to the hole and initid reading (O recording) is done
The installing tool is removed and the cell is ready for overeoring.
A new core is drillai with the 76 mm 0 diamond drill, thus stress relieving the bottom of
the borehole. The corresponding stra'ns at the end of the core are recorded by the strain
gauge rosette.
The core is catched with a special core catcher, and irrmediately after removal from the hole
the second recording is done. From the recorded strains the stresses in the plane nonnal to
the borehole, may be calculated when the elastic parameters determined from laboratory
tests are known.
Contact
Plastic mass
Cables