Study of Soil Temperature and Subsurface Flow Characteristics Under Nature Disaster

• Main Authors: JrSheng Yang, 楊志盛
• Other Authors: JetChau Wen
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/29120872397416075620

碩士 === 國立雲林科技大學 === 環境與安全工程系碩士班 === 89 === In the study, of the unsaturated soil, six sensors at each borehole were buried at different depths: 15cm, 30cm, 45cm, 60cm, 90cm, and 120cm from ground surface on the campus of National Yunlin University of Science and Technology. There are totally 10 boreholes for water content potential measurement and 1 borehole for soil temperature monitoring. The purpose of soil temperature monitoring is for analysis of Grey relational on the measured soil temperature. It is found, using the Grey relational coefficient, Grey relational grade, the differential of Grey relational coefficient and the differential of Grey relational grade, that the soil temperature characteristics can be examined during the periods of sunny, rainy, interchange between sunny and rainy, stormy and seismic days. For instance, under the sunny day circumstance, the four parameters of soil temperature, the Grey relational coefficient, Grey relational grade, Grey relational coefficient change rate, Grey relational grade change rate of the daily morning average of soil temperature, are stable with an increase of time. However, for the cases of typhoon, the four parameters of soil temperature are unstable. Specifically, the four parameters are highly fluctuated for strong typhoon (such: Zeb, Bilis). For seismic periods, the four parameters show irregularly for the seismic grade over 5. However, for the grade lower than 5, the four parameters do not show irregularly. Finally, the study presents the subsurface flow characteristics before and after the Chi-Chi earthquake. It is found the subsurface flows are stable and regular before the time of Chi-Chi earthquake. After the Chi-Chi earthquake happened, the subsurface flow at the study site has changed irregularly. The change opportunity of the subsurface flow direction after the Chi-Chi earthquake has 60% compared to the subsurface flow direction before the Chi-Chi earthquake. It is reasonable because the unsaturated soil structure was changed dramatically after the Chi-Chi earthquake. Therefore, the subsurface flow direction was irregularly changed after the Chi-Chi earthquake.