Tunnel second lining back cavity detector and detection method

The invention discloses a tunnel second lining back cavity detector, which comprises an alternating current converter, a push-button stop switch, a push-button start switch, a transfer switch, a powerindicator light, a work indicator light, an air switch, a limiter, at least two second lining embedded wires and detection end wires, the second lining embedded wires are longitudinally distributed at a vault along a tunnel, and the alternating current converter realizes contact conversion among the limiter, the indicator lights and the push-button switches; and the limiter is a DF-96E water pumpfull-automatic water level controller. The invention discloses a tunnel second lining back cavity detection method at the same time. According to the tunnel second lining back cavity detector, diseases of second lining back cavities are fundamentally avoided, the stability and durability of the tunnel structure are guaranteed, and operation and the full life effect of the tunnel are improved. 本发明公开了一种隧道二衬背后空洞检测仪，包括交流转换器、按