Bridge tunnel crack depth measuring instrument

The utility model relates to the technical field of measuring instruments, in particular to a bridge and tunnel crack depth measuring instrument which comprises a base, a case is arranged at the top of the base, a storage battery is arranged in the case, a forward and reverse motor is arranged in the base, a lead screw is arranged at the driving end of the forward and reverse motor, and a screw rod is arranged at the driving end of the lead screw. A threaded sleeve is arranged on the outer side of the lead screw, a moving groove is formed in the position, corresponding to the threaded sleeve, of the base, an adjusting cylinder is arranged at the top of the threaded sleeve, a telescopic cylinder is arranged in the adjusting cylinder, an adapter is arranged at the top of the telescopic cylinder, and fixing blocks are arranged on the left side and the right side of the top of the adapter. The top of the fixing block is provided with a telescopic rod, the outer side of the telescopic rod is sleeved with a spring,