On-line steel rail fracture monitoring system and knock detection method

The invention discloses an on-line steel rail fracture monitoring system. The system comprises a knock unit, a signal acquisition sensor group and a train passing induction device which are arranged on the side surface or bottom surface of a steel rail, a signal amplifier and a control unit which are arranged beside a railway track, and an upper computer which is arranged in a public work-related diagnosis room, wherein the knock unit and the train passing induction device are connected with the control unit through lines; the signal acquisition sensor group is connected with the control unit through the signal amplifier; and the control unit is connected with the upper computer. The invention also discloses an on-line knock detection method by using the system. The method comprises the following steps of: automatically detecting train passing by using the train passing induction device, sending a detection signal to the control unit, controlling the knock unit to knock the steel rail to generate sound waves, transmitting a signal acquired by a signal acquisition sensor to the control unit for analysis processing through the signal amplifier, and sending processing information to the upper computer. By the system, train passing can be detected in real time, the completeness of the steel rail is determined, and the method is reliable and practical.