Abstract: A locally-anchored, self-drilling, deformable, hollow rock bolt has one or more intermediate local anchors each of which is flanked by two relatively elongateable shank segments. After grout is supplied through the hollow interior of the rock bolt while the rock bolt is in the drilled borehole, each anchor fixes the bolt to the rock mass, whereas the adjacent smooth shank segments can deform and even yield to accommodate rock fracture. The local anchors may be of relatively short extent when compared to the shank segments. One or more of the intermediate anchors could be formed by a coupler connecting adjacent bolt sections together and/or by shaping the bolt and/or by providing an external anchor. The innermost end of the rock bolt may be formed from or bear a drill bit. The drill bit can have dual functions of drilling the borehole and serving as the innermost anchor of the bolt.

Abstract: A locally-anchored, self-drilling, deformable, hollow rock bolt has one or more intermediate local anchors each of which is flanked by two relatively elongateable shank segments. After grout is supplied through the hollow interior of the rock bolt while the rock bolt is in the drilled borehole, each anchor fixes the bolt to the rock mass, whereas the adjacent smooth shank segments can deform and even yield to accommodate rock fracture. The local anchors may be of relatively short extent when compared to the shank segments. One or more of the intermediate anchors could be formed by a coupler connecting adjacent bolt sections together and/or by shaping the bolt and/or by providing an external anchor. The innermost end of the rock bolt may be formed from or bear a drill bit. The drill bit can have dual functions of drilling the borehole and serving as the innermost anchor of the bolt.