本研究利用表面波譜法(SASW)對地盤灌漿時灌漿體上覆土層之材料性質與土層厚度之探討。在本研究中將以有限差分數值分析軟體FLAC3D來模擬表面波譜法,探討不同參數對表面波譜法頻散曲線之影響,影響參數包括了敲擊延時(10ms、6ms)、土層厚度(2m、3m、4m)以及土壤波傳速度。 利用數值分析軟體FLAC3D以模擬表面波譜法之進行,建立不同收波器間距之頻散曲線所集合成的複合頻散曲線,並由複合頻散曲線中繪製一條代表性的頻散曲線。由單一土層之頻散曲線與含灌漿體的頻散曲線之比較,來評估上覆土層之厚度。在本研究中也利用複迴歸分析將代表性頻散曲線之斜率迴歸成估算土層與灌漿體波傳速度之公式,最後配合現地案例以說明本研究評估灌漿體上覆土層厚度與波速估算的方法。 從本研究的結果顯示,敲擊延時對頻散曲線之影響不大,另外頻散曲線的相速度會隨土層的剪力波速增加而增加。混凝土灌漿體之上覆土層厚度可由代表性頻散曲線圖推估出來,而土層與灌漿體之剪力波速則可藉由迴歸公式求出。
This study used SASW method to evaluate the thickness and material properties of upper-layer soil in soil grouting. In this study, a finite difference numerical analysis software FLAC3D will be used to simulate the SASW method. In the parametric study of dispersive curve, the delay of loading, upper-layer soil thickness and shear wave velocity were varied. The representing dispersion curve was evaluated from some composite dispersion curves in various distance of receivers by using numerical analysis software FLAC3D. By comparing the representing dispersion curve of a single soil with that of a stratum with grouting body, thickness of upper layer soil can be found. The regression formulas will be developed from the slopes of the representing dispersion curve to calculate the shear wave velocity of soil and grouting body. Finally, a practical case study was performed in order to illustrate the proposed procedures for evaluation of the thickness of upper layer soil and shear wave velocity by SASW method. From the results of this study, the delay of loading is insignificant influence factor on dispersion curve. The phase velocity increases with increasing shear wave velocity of upper layer soil.