Novel hoop strain measuring device

The invention discloses a novel hoop strain measuring device which comprises a sensor constituted of a fixed plate and a strain plate as well as a metal wire, wherein the fixed plate is firmly disposed on a base; the right end of the fixed plate is firmly connected to the right side of the top part of the base by a bolt; a wire wrapping hole is formed in the left end of the fixed plate; a first through hole and a left limiting hole are formed in the left side of the base; a right limiting hole, a second through hole and a third through hole are formed in the right side of the base; one end of the metal wire is sintered on the wire wrapping hole; the metal wire successively passes through the first through hole and the left limiting hole, is then wound on a rock sample and then successively passes through the right limiting hole, the second through hole and the third through hole; and the other end of the metal wire is sintered on the bolt. The device disclosed by the invention omits the step that the strain plate must be adhered on the outer surface of the rock sample in each experiment of a hoop strain, wherein deformation of the fixed plate is driven by the metal wire wound on the outer surface of the rock sample, so that specific data and a changing curve of the hoop strain of the rock sample during a loading process can be obtained.