| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 90 === Influence of Fines Content of Sandy Soil on Soil Freezing
Thesis Advisor：Hung-Jiun Liao
Graduate Student：Bo-Shiang Chao
June 2002
ABSTRACT
Most of the silty sand layers of the alluvial deposits in Taiwan contain a certain percentage fine particles (< #200). To study the influence of fines content on the freezing behavior of sandy soil, three different fines contents (5%, 20%, and 30%) were used in this study. The advance of ice front and the temperature distribution within the soil was simulated with the TEMP program. Based on the simulation results, the heat conductivity coefficient of test soil can be determined. As the fines content increases, the rate of temperature drop within the soil decreases, the growth of frozen soil slows down, and the amount of vertical freezing heave increases. When the soil temperature approaches 0℃, the ice front induced earth pressure increases significantly. Based on the results of the parameter study using TEMP program, the growth of frozen ground is affected by the freezing time, the freezing temperature, the unfrozen volumetric water content, and the heat conductivity coefficient.
To apply the ground freezing technique to obtain undisturbed samples from a sandy layer, a full scale sampling test was carried out in Yun-Lin. The test results indicated that the freezing of in-situ sandy soil was strongly affected by the fines content. Due to the high fines content of the in-situ soil (~ 50% to 60%), some of the target freezing zone was not frozen after five days freezing. Only in the frozen area, sandy soil samples could be successfully recovered from the ground.
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