DIAGNOSING METHOD OF DETERIORATION OF MANHOLE IRON COVER

摘要

PURPOSE:To determine a quantitatively degree of deterioration and take a diagnosis speedily and easily by determining quantitatively the damping coefficient of the amplitude of oscillation and waveform variation at the time of an impulse stroke. CONSTITUTION:An iron cover 1 supported by an iron cover suspender 15 is struck by a device 11 and impulse oscillation that occurs to the cover 1 is acquired by a reception part 12, so that the mechanical scillation is transduced into a voltage signal by a pickup coil for reception. This signal is amplified by the amplifying part 13a of a signal analyzing part 13 and inputted to a signal processing part 13b. Then, the time axis from the point of time of the stroke is sectioned and attenuation patterns are modeled to calculate oscillation damping coefficients alphai (i=1-n-1) between two adjacent points. Similarly, oscillation damping coefficients betai (i=1-n-1) of a sound iron cover are calculated to calculate gammai=alphai/betai, and it is judged that the degree of deterioration increases as gammai leaves from one, thus deterioration patterns are classified according to (i).