| Summary: | 碩士 === 逢甲大學 === 土木工程所 === 99 === In recent years, environmental awareness is awakening in Taiwan, and people are putting more emphasis on pollution issues. Especially in the modern environment, underground pollution is toxic and may trigger more serious and wider impacts once the pollutants reach groundwater level. The common pollution source is organic solution, also called non-aqueous phase liquid (NAPL). Due to rainfall infiltration into soil and the underwater level rising over a long period, the range of pollution expands progressively. The pollution are always seriously devastating when it is finally discovered. Underground pollution increases the difficulty of inspection, thus the selection of adequate inspection methods is essential. The majority of traditional inspection methods are destructive surveying, such as monitoring wells, drilling, and excavation. These surveying methods are manpower-intensive and fail to precisely identify the range of polluted areas. With advancing civil engineering techniques and instruments, many non-destructive testing (NDT) methods have been developed: such as visual inspection (VT), liquid penetrant inspection (PT), magnetic particle inspection (MT), ultrasonic inspection (UT), radiographic inspection (RT), impact-echo method, ground-penetrating radar (GPR), rebound hammers, rebar scanners, and corrosion potential. Each method has advantages and disadvantages. According to various characteristics and the environment, the methods can be varied to conduct inspections. Among the non-destructive testing methods that have been widely applied and studied, GPR occupies a certain place.
Inspecting underground pollution via GPR is a potential and valuable practical geotechnical engineering technology.This thesis employs GPR to inspect the in-situ underground pollution case under one gas station in the Wugu area of New Taipei City. Using in-situ lines and signal processing, the author can depict the polluted area, and the overall pollution trend. The 2D section figures are used to depict the polluted area and the general flowing pattern of penetrant whereas 3D diagrams of GPR signal near the in-situ coring section can show clearly the area of pollution. To verify the feasibility and practicability of GPR application on underground pollution inspection, this study employs in-situ core drilling samples. After comparing testing results and core samples, the level of pollution and the area of light non-aqueous phase liquid (LNAPL) determined by GPR is accurate. Therefore, GPR is an effective method to inspect underground pollution.
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