ROCK BOLT

FP0863-00 47 A rock bolt 1 which is embedded in a hole 103 provided in ground 101 includes: a movable side rod body 3 which includes movable side extension portions 16, 17, and 18 disposed inside the hole 103 to be elastically deformable; a fixed side rod body 2 which is 5 provided in parallel to the movable side rod body 3 inside the hole 103; a cylinder casing 22 which movably connects the movable side rod body 3 to the fixed side rod body 2; a compression spring 24 which generates a force in a direction A2 opposite to a movement direction A1 when the movable side rod body 3 moves with respect to the fixed side 10 rod body 2; and a slide regulation mechanism 23 which defines a movable range of the movable side rod body 3. The rigidities of the movable side extension portions 16, 17, and 18 of the movable side rod body 3 are larger than the stiffness of the compression spring 24. 15