Multistage resistance-increasing anchor rod and construction method

The invention discloses a multistage resistance-increasing anchor rod and a construction method. The multistage resistance-increasing anchor rod comprises a rod body, wherein a rod body check block is fixed at the front part of the rod body; a jacking rod is connected to the rear part of the rod body; a plurality of self-expandable devices with hollow structures sleeve a rod body between the rod body check block and the jacking rod; the jacking rod can push the self-expandable devices to move; the front part of each self-expandable device is of a conical structure; a hollow connecting rod is arranged at the middle of each self-expandable device; a plurality of wedge sheets are arranged at the rear part of each self-expandable device along the circumferential direction of the self-expandable device; the wedge plates of the adjacent self-expandable devices are connected with the conical structures; a fixing device is arranged at the tail of the rod body, has removability, can be used for changing resistance increasing series and facilitates adopting multiple resistance increasing series settings for engineering practice; the stress is simply applied; the rear ends of the self-expandable devices are expanded by screwing bolts; the wedge plates in a shape like a Chinese character mi at the rear ends of the self-expandable devices adopt the design that the front parts are thick and the rear parts are thin, so the penetration of conical ends is facilitated; meanwhile, the stretched wedge plates can be conveniently inserted into surrounding rock or the insides of surrounding soil bodies, so that the frictional resistance between the rod body and the soil bodies is increased.