Experiment for identifying free span of buried gas pipeline under internal excitation load

摘要

Free span is a great danger and an unavoidable problem for buried gas pipeline. In this paper, a method for identifying buried gas pipeline free span based on vibration signal analysis under internal excitation load is experimentally studied. Collected signals are pre-processed by sliding average method to reduce noise and smooth the vibration curve. Two evaluation indicators, frequency response function and response signal energy, are established to evaluate free span detection results. A free span detecting apparatus is developed, some experiments were carried out and their detection results are analyzed to verify the reliability of the two indicators and feasibility of the method. The experimental results show that the free span can be identified by two indicators and the proposed method is feasible. Some parameters, such as excitation force, frequency sweep rate etc., have a serious influence on free span detection results.