以敲擊回音法測漸變斷面混凝土厚度之可行性

Abstract

本論文主要研究目的是利用敲擊回音時間領域的訊號分析技術，於接收探頭中的位移波形嘗試判斷反射內P波到達的時間，並利用所量測到的P波波速，來計算漸變斷面的厚度。本研究採用表面P波、內P波、與圓柱試體敲擊回音頻率域所得之P波，來檢驗P波之波速。研究結果顯示，由內P波所推求到的厚度最準，但是此法於現地實際狀況下恐因對面有障礙物而不能做對向量測；不過，以表面P波所推求出的厚度，其誤差值亦有在5%以內，且此法只需單面量測波速。所以，以敲擊回音時間域的技術來判斷漸變斷面的厚度，是有一定之可行性的。

The objective of this thesis is to use the technique of impact echo in time domain to get insight into P-wave and use the measured speed of P-wave to determine the thickness of varied thickness plate. The measured speeds of P-wave in my study include surface P-wave, internal P-wave and P-wave measured from cylinder which taking core from the plate in frequency domain. The results of study show that the estimated thickness by impact echo in time domain is feasible especially using the speed of internal P-wave but it is not feasible in true situation. However, the measurement of speeds from surface P-wave solves the problem and the error can be controlled in 5%.