| 摘要 |
A device is provided to measure the length of an unknown structure. Matrix-arranged seismic sources and de tectors are se t on a detected structure to obtain transmission speeds (Vei) read by the detectors. Each of the detectors measures three time-series seismic components at three directions, separately, comprising a vertical component (V), a first horizontal component (H1) and a second horizontal component (H2) in a time domain. After a Fourier transform, V, H1, and H2 are converted into Fv, FH1, and FH2 spectrums in a frequency domain. Then, the spectrums are separately processed through a simple calculation, whe re FH1/Fv an d FH2/Fv are obtained throug h a h o rizo n tal-to-ve rtical s p e ct r a I r a tio m e t h o d to figure out the main frequency (F) of the detected structure. At last, a concept of frequency, velocity, and cylindrical length related to a standing wave transmitted in a cylinder (column) with an end fixed is used. By using L=Vei/4F for figuring out length, the detected structure with the part buried underground can be estimated through calculation. Even other possible structure like pile foot buried under interface can be found. Hence, the present invention can replace traditional monitoring devices for clarifying a structure related to an abutment, a pier, a pillar, a retaining wall or a bridge with better detection effect. . . .. . . . . . . . . . .. .. . . . . . ... . . . . . . . . . . . . . . . . .. .. . . . . . ... . . . . . . . . . . ... |
