應用透地雷達測定淤積泥砂之相對介電常數與物理特性

Using Ground Penetrating Radar to Measure the Relative Dielectric Constant and Physical Properties of Sediments at the Water Bottom

黃天福(Tieng-Fu Huang) ； 梁昇(Sheng Liang)

《中華水土保持學報》 32卷3期 (2001/09) Pp. 163-173

https://doi.org/10.29417/JCSWC.200109_32(3).0001

摘要

透地雷達（GPR）是一種應用極廣之地球物理工具，但是目前尚未有利用GPR探測水底淤積泥砂之探討，包括GPR之應用與淤積泥砂之電磁特性。本文應用模型試驗來探討此問題。利用獲自模型試驗中砂質與細粒沈積物之各項測定值與GPR點測記錄，分析沈積物之相對介電常數（ε_(rs)），密度（γ_t），容積含水量（θ），及空隙比（e），並利用這些資料建立θ-ε_(rs)，γ_t-ε_(rs)，及γ_t -θ或γ_t-e之關係，且都獲得值得信賴之結果。砂質沈積物之結果大致上與前人研究潮濕砂質土壤之結果相符。但是獲自細粒沈積物之结果卻與前人研究細粒土壤之結果有極大之差異，此差異係來自容積含水量之變化。由於水面下沈積泥砂空隙比之變化反映在容積含水量之變化，亦反映在相對介電常數之變化，因此可用相對介電常數來表示沈積物之密度，空隙比或容積含水量。

關鍵字

透地雷達 ； 沈積泥砂 ； 相對介電常數 ； 容積含水量 ； 沈積泥密度

並列摘要

It has not yet been discussed whether ground penetrating radar (GPR is applicable in detecting sediments at the bottom of water. Also, the electromagnetic properties of sediments have not been elucidated. This research tries to discuss this problem using a model test. The relative dielectric constant(ε_(rs))，density(γ_t) ,and volumetric water content(θ) or pore ratio(e) of sediments are analyzed. The relationship ofθ-ε_(rs)，γ_t-ε_(rs)，andγ_t-θ orγ_t- e are also established and are reliable. The results of the sandy sediments from the model test coincide with that from the wet sandy soils test earlier. The results of the fine grain sediments show a great difference from that of fine grain soils. This difference is caused by the great difference in volumetric water content. Because the change in the pore ratio of sediments at the bottom of water can be reflected in the volumetric water content, it can also be reflected by a relative dielectric constant.

並列關鍵字

GPR ； sediments ； relative dielectric constant ； volumetric water content ； density of sediment