ROCK MASS DEFORMATION DETECTION STRUCTURE, ROCK MASS DEFORMATION DETECTION SYSTEM AND WASHER FOR ROCK MASS DEFORMATION DETECTION

PROBLEM TO BE SOLVED: To easily and promptly detect rock mass deformation through visual recognition from a separated place and to eliminate time and efforts for special work such as installing a load detection device between a nut and a washer or the need to especially elongate a protruding length of an anchor material such as a lock bolt from a rock mass.SOLUTION: A rock mass deformation detection structure comprises: a lock bolt 11 which is installed in a rock mass 3 and provided with a male screw part 111 in the vicinity of an end of a portion protruding from the rock mass; a washer 12 which is extrapolated to the protruding portion of the lock bolt 11; and a nut 13 which is threaded with the male screw part 111 of the lock bolt 11 and presses the washer 12 to the side of the rock mass while being in contact with the washer 12. In a region on a nut-side surface 123 of the washer 12 which is not in contact with the nut 13, a coating 125 is provided which has a color different from that of a body 121 of the washer 12 and is exfoliated by deforming the washer 12 a predetermined amount or more.