Stress-relief borehole measurements before and after quarrying a block of Barre Granite at Barre, Vermont

Abstract

In situ stresses were measured in a 10X10X5.7-m block of Barre Granite of Devonian age at the Wetmore and Morse granite quarry at Barre, Vt., before and after it was quarried. The stresses were measured with the U.S. Bureau of Mines borehole deformation gage in both the horizontal and vertical planes. Anomalously high stresses in both planes were observed in the block before quarrying. Relatively small stresses remained in the block after quarrying. Stresses measured in the floor beneath the block and from a horizontal boring in the 67-m vertical backwall behind the block, however, showed that the quarrying caused little change other than to the block. Additional measurements were also taken in granite in the Barre, Vt., area near the Wetmore and Morse and Adam quarries and in schist near the Pirie quarry.