圖書典藏及影音數位平台

高鐵沿線下陷原因除與過去常見之地下水抽取有關外，亦與高鐵工程構造物荷重對墩柱下陷及高鐵行進振動所造成墩柱壓密沈陷息息相關。故本計畫將模擬雲林地區地下水抽取之地下水水位變化，與所觀測地層下陷量之關係，並就該區鑽探取樣之土壤地質特性，評估上述地下水水位變化、高鐵工程構造物之靜態荷重對墩柱下陷及高鐵行進振動所增加地表荷重條件下對本區地層之應力變化分布、地層下陷量及下陷潛勢之影響，俾利本署研擬地層下陷防治執行措施之科學數據參考依據。

Land subsidence in Yunlin area has been observed due to over pumping of groundwater for a long time. The insufficient supply of surface water for water use sectors including livelihood, industry, farming and some agriculture was the main couse. In 2010, the maximum subsidence area and rate are in Yunlin area of the western Taiwan. It poses the safety risks of the high-speed rail structures through the Yunlin area. The subsidence occurs not only by groundwater pumping but also by both the static loading on the pier under the high-speed rail structures and the dynamic vibration under the high-speed rail during operation. The objective of the project is to model the relationship between the water level variation of the groundwater pumping and the observed amounts of the land subsidence in Yunlin area. Three influences of stress distribution, settlement and subsidence potential are performed with the variation of groundwater level, the static loading on the pier under the high-speed rail structure, and the incremental loading under the vibration of the high-speed rail during operation. The land subsidence caused by over pumping of groundwater including primary and secondary consolidation. Two types of consolidation are considered by respectively the effective stress of Terzaghi using INTERBED model and the clay interbed dehydration theory. The amounts of the land subsidence caused by the static weight of the high-speed rail piers are estimated by the vertical stress increment of Boussinesq method. And the other hand, the amounts of the land subsidence caused by the dynamic consolidation of the high-speed rail during operation are adopted the three-dimensional finite element model within the equation of damped vibration motion. With an aim integrating analysis methods, the project computed amounts of the land subsidence caused by the groundwater variation under the primary and secondary consolidation, the static loading consolidation of the high-speed rail piers, and the dynamic consolidation during operation. The results of this analysis provide the quantitative amounts of the land subsidence due to the groundwater pumping and the operation of high-speed rail. The settlement amount along the subsidence in Huwei and Tuku caused by pumping groundwater are about 40 cm and 35.1 cm, respectively. For engineering structures due to loading by Yunlin station special zone, 158 county road and expressway 78 station, the maximum amount of subsidence can be estimated in 2012 are about 1.56~3.24 cm, 0.54~1.04 cm and 1.60~6.68 cm, respectively. The subsidence caused by the vibration of the dynamic analysis can be estimated minimal impact on the surface or deep layer.