| 摘要 |
<p>PURPOSE:To make it possible to detect extent of chemicals penetration into the ground by making an exciter, installed in the vicinity of a hole for chemical grouting, generate modulated waves, and further by having the waves received by a plurality of pairs of receivers that are installed in several radial directions with the hole as the centre. CONSTITUTION:In the vicinity of a hole 4 for chemical injection, an exciter 5, having a modulated wave generator capable of modulating waveforms of Reyleigh-type surface waves, is provided. On each of a plurality of lines A-C in radial directions with the hole 4 as the centre, a number of pairs of excitation frequency receivers 1-3 are dispersedly installed at prescribed intervals S. Then time T required by the surface wave traveling a distance between each pair of the receivers 1-3 is measured for each of the various excitation frequencies (f) that is generated by thew exciter 5 one after another. The average velocity VR is calculated by the values obtained for T against, S, and the depth D for investigation is calculated from the values VR and (f). By knowing VR for each of the D's, extent of penetration of the chemicals into the ground can be detected. For easy identification of parts injected with the chemicals, weight- increasing agent such as iron sand, iron powder or the like are mixed with the chemicals.</p> |
