| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 98 === How does focused bedrock exfiltration influence the failure process of a
hillslope? If a hillslope has already begun to fail, what features of the failure or the
hillslope can be used to distinguish between a failure process controlled by rainfall
and a failure process controlled by a point source of bedrock water? These questions
play a key role in the investigation of a landslide located in the north central
mountains of Taiwan, known as Tieliku. The Tieliku slope failure is hypothesized to
have been influenced by high pore water pressures caused by a focused source of
bedrock water exfiltration. Research of Tieliku is conducted using field and laboratory
techniques.
First the history of the slope failure is documented using aerial photographs,
survey measurements, high resolution air LIDAR measurements and slope movement
data collected from annual rings of trees growing along the upper edge of the scarp.
Second, a laboratory analogue hillslope model is used to test hypotheses regarding
soil water, bedrock topography and landslides. Results of the analogue model tests are
quantified via detailed topography measurements and sediment production histories
generated using image analysis techniques.
In total, six different experiments are performed and contrasted. Through
comparison of Tieliku field data to experiment results, several lines of evidence are
found to support the hypothesis that the Tieliku slope failure was influenced by
localized, high pore pressures at the top of the failure scarp. In the experiments,
localized high pore pressures result from flow exiting a buried pipe. At Tieliku,
elevated pore pressures may be caused by focused bedrock exfiltration.
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