Detection and Fault Diagnosis for Acoustic Vibration of Pipes Buried in Soil

In order to protect pipeline transportation, it is very important to carry out such researches as active protecting and accurate positioning. Analyzed the vibration characteristic of fluid-filled pipes buried in soil by the Flügge shell equation and Helmholtz equation, the dispersion equation of fluid-structure and structure-soil interaction was derived from shell dynamic equation, Analyzed the frequency dispersion characteristic of coupling system, discussed the method of wave propagation with power flow. the results show that the load brought by medium around pipes affects coupling degree and acoustic characteristic of coupling system, low-freguency acoustic wave in pipeline can propagate long distance with little falloff, the typical acoustic spectrum can be picked up and recognized with the algorithms of Hidden Markov Model(HMM) and Artificial Neutron Network(ANN), it provides theoretic base for real-time monitoring and fault diagnosis in pipeline long-transportation system by using acoustic method.