Numerical Analysis on Groundwater Table Variations in Chih-Shan Observation Well, Induced by the Hengchun Earthquake.
Date Issued
2010
Date
2010
Author(s)
Kuo, Chien-Pang
Abstract
Since located at the borderline between Eurasian Plate and Philippine Sea Plate, the orogeny is very active in the area and earthquakes caused by dislocation of geologic faults frequently occurred. The groundwater-level variation is one of the characteristics induced by earthquakes. The cause of this phenomenon is generally considered as the energy stored in the crust would be discharged when earthquake occurred, which altered the earth stress distribution, thus, the developed excess pore pressure led to groundwater-level change.
Lai(2007) conducted a dynamic analysis using FLAC program to develop a numerical model of excess pore pressure based on Finn theory, the results confirmed the model provided a fine simulation of the hour-recorded groundwater-level change in Jhuo-Shuei River alluvial fan caused by Chi-Chi earthquake, but no good description for oscillation. Chen(2008) developed a fault thrusting model and applied Biot theory, his model had rational simulation for the pore pressure fluctuation, but the amount of pore pressure changes was different.
For understanding of groundwater-level changes caused by earthquakes, this research conducted numerical analysis based on two different theories of pore pressure generation, and compared the simulation results with the data from the high-frequently monitoring Chih-Shan observation well for the groundwater-level change caused by Hengchun earthquake in 2006, Dec. 26.
The Finn mode simulation results were generally larger than the water-level change recorded, contrarily the Biot mode had a lower water-level change simulation compared to the record. The oscillation phenomenon of groundwater was better described by the Biot mode, while Finn mode provided better description for stepwise groundwater change. Parametric study for poisson’s ratio suggested little influence. The Finn simulation had better corresponding result with the earthquake record than those of Biot simulation. In conclusion, the parameter used in this research were not able to provide good results, it would be necessary to further consider proper soil parameters improving simulation.
Subjects
earthquake
groundwater change
dynamic response
dynamic pore pressure
Type
thesis
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