| Summary: | 碩士 === 國立雲林科技大學 === 營建工程系碩士班 === 94 === Taiwan High Speed Railroad (THSR) is more vulnerable to ground subsidence than common railroads and highways, because of its great demand in safety and high cruising speed. THSR travels through the Yunlin County, which overlies the southern part of Draw-Shua River alluvium fan (DSAF). This area possesses high potential of ground subsidence subjected to environmental disturbance because of its substantial compressibility. Recent measurements depicted the severity of subsidence problems in the site, and possible influential factors are composed of groundwater drawdown, soil property, and surface loading, the relationships among which require further investigation.
The objective of this thesis is intended to study the mechanism of ground subsidence of THSR over the Tu-Ku section. Various historical monitoring data of BM elevations, groundwater elevations, and soil properties in the local areas from different sources were collected and complied. In addition to common statistical methods, the technical analysis and diagnosis technology were adopted to perform the corresponding cross-comparison study, in order to clarify the relativeness among ground subsidence and influential factors.
Analysis results indicate that: a) serious subsidence areas along the THSR over Yunlin are distributed in the regions of Tu-Ku, Hu-Wue and Yuan-Chan, with average annual subsidence rate of 6cm/yr; b) substantial groundwater drawdown areas are located in Hu-Wue and Tu-Ku, with average annual drawdown rate of 25cm/yr, which is related to local spatial distribution of deep wells, and the same pattern of time variations in BM and groundwater elevations in Hu-Wue illustrates their high correlation; major portion of surface subsidence is contributed by the compression of soil layers in depth between 70 and 300m, evidenced by the three settlement monitoring wells in Tu-Ku, Hu-Wue and Yuan-Chan. In order to enhance the applicability of current research accomplishment, more complete in-situ instrumentation data are required.
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