Using Ground Penetrating Radar to Study the Electromagnetic Properties of the Settled Sediments

• Main Authors: Tien-Fu Huang, 黃天福
• Other Authors: Sheng Liang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/81070451741265018915

博士 === 國立中興大學 === 水土保持學系 === 89 === Summary It is not yet discussed whether ground penetration radar (GPR) is applicable for detecting the sediments at the bottom of water or not, and also the electromagnetic properties of sediments. This research tries to discuss this problem by model test and field investigation. From model test, the relative dielectric constant ( ), the density ( ), the volumetric water content ( ), the pore ratio (e) of sediments and the propagation velocity of electromagnetic wave ( ) in sediments are analyzed. The relationship of － or － ， － or － ， － or － ， － and －e are also established. Using the results of fine grain sediments from model test and field investigation, the relative parameters and their relationship are prepared. The results of sandy sediments from model test coincide with that from wet sandy soils before. The results of fine grain sediments have a great difference from that of fine grain soils. This difference is caused by the great difference in volumetric water content. Because of the change in void ratio of sediments at the bottom of water can be reflected by volumetric water content or density, therefore it can also be reflected by relative dielectric constant. Consolidation of sediments by its own weight, increasing with the accumulated height(y), decreases the void ratio or volumetric water content, and can also be expressed by relative dielectric constant and height of sediments. According to the magnitude of relative dielectric constant of sediments and the reflection configuration in GPR profile, the sedimentation time and the kind of materials can be known. The depth of investigation is limited by two factors, the great relative dielectric constant of water and sediments and the conductivity of fine grain sediments. In this research, as the depth of sediments greater than 100cm, or the depth of water less than 130cm, the resolution of GPR profile becomes decrease. Because of the relationships between the electromagnetic properties and the physical properties of sediments, the field investigation for the physical properties of sediments can be conducted easily. Known the dielectric constant of sediments, its depth, volume, and density are also known. Therefore, this result can be used for sediments remove project and studying the sedimentary course after a flood event.