透地雷達(Ground Penetrating Radar,GPR)是一種具更高解析度的非破壞探測技術,為一種地球物理探測方法,利用電磁波在地層中的穿透與反射等特性,若以透地雷達非破壞探測技術來進行應可解決問題,且能更快速、經濟的改善調查之品質,然而透地雷達電磁波因不同地層界面間介電常數不同而產生與原入射波不同之反射電波。本研究利用400MHz透地雷達天線頻率配合 Total Variation對透地雷達影像雜訊進行抑制,藉由台中液化天然氣廠港南路柔性鋪面下陷維護路段進行現地試驗、影像蒐集,最後判別路面下陷部位與施測時天線拖曳時逤造成的現象是否有雜訊抑制成效。研究結果顯示Total Variation採用Soft Thresholding的處理模式,可以增加資料處理速度,在處理中約在疊代100次後,結果即可達到能量最小的要求,其對柔性鋪面下掏空所產生的雜訊與施測時天線拖曳時逤造成的現象所產生的雜訊抑制也有相當的效。
Ground penetrating radar (also referred to as GPR) is a nondestructive probing method with improved high-resolution. The principle of this geophysical probing technique uses the penetration and reflection characteristics of electromagnetic waves while propagating through ground layers. Therefore, the nondestructive GPR probing technique may solve problems in a quicker, more economic matter, and improve survey quality. When the GPR electromagnetic waves struck different ground layer boundaries, the specific dielectric constant of each layer result causes the reflective wave differ from the original incident wave. In this study, we applied the GPR technique for an on-site test of flexible pavement subsidence at a section of Gangnan Rd, Taichung LNG Terminal. The investigation used a 400 MHz transducer, which the captured GPR images were then processed by total variation denoising. The final images were used to determine the effectiveness of noise reduction with the road subsidence and tracks when dragging the transducer. Results showed when we used the soft thresholding algorithm for total variation, it enhanced data processing speed; with only around 100 iterations the results were achievable by using the required minimum energy. The method also proved to have effective noise reduction to the noise signals from the hallowed flexible pavement and dragging of the transducer.