NEW EVALUATION METHOD OF PS-ANCHOR FORCE BY USING MAGNETIC SENSOR AND ITS APPLICATION IN A LARGE UNDERGROUND POWERHOUSE CAVERN

Abstract

Magnetic anisotropy sensor is used for nondestructive measurement of stresses of a nut which is part of the head part of a PS anchor usually used for stabilizing rock mass in large scale underground caverns. Since the stresses in the nut reflect the level of axial force in the anchor, the results of the stress measurement can be used indirectly to estimate the current axial forces of PS anchors. By knowing distribution or changes in PS anchor forces, one can establish a fundamental safety assessment routine for large-scale underground caverns.