Tunnel section detection instrument

The utility model relates to the technical field of tunnel detection equipment. The tunnel section detection instrument comprises a vehicle body, a placing groove is formed in the top of the vehicle body, a connecting shaft is fixedly connected to the inner surface of the placing groove, a vertical plate is movably connected to the outer surface of the connecting shaft in a sleeving mode, a fixingblock is fixedly connected to the side face of the vertical plate, and a first spring is fixedly connected to the top of the fixing block. Tunnel section detection instrument, an inner cavity is formed in a vertical plate; a second spring is additionally arranged in the inner cavity; a cover plate is additionally arranged above the vertical plate; the top of the cover plate is provided with a round hole through which the laser probe can irradiate; when the falling stone descends to hit the cover plate, the first spring is compressed to enable the cover plate to move downwards and enable the pressing rod to press the