HR: 1340h
AN: H53C-1402    [Abstracts]
TI: The Abnormal Pore Pressure Response Between the Interface of Colluvial and Bed Rock in a Landslide Area
AU: * Hsu, H
EM: hhhsu@ctu.edu.tw
AF: Department of Civil Engineering, Chienkuo Technology University, No.1, Jieshou N. Rd., Changhua City, 50094, Taiwan
AU: Dong, J
EM: jjdong@geo.ncu.edu.tw
AF: Institute of Applied Geology, National Central University, No.300, Jhongda Road, Jhongli, 32001, Taiwan
AB: The Hungtsaiping Landslide triggered by Chi-Chi earthquake covers an area of hundreds of hectors. The rock mass is covered by a thick colluvial that is as deep as 82m. To explore the sliding mechanisms, GPS, inclinometer and fiber optic displacement and water pressure sensing systems were used to monitor the status of the landslide. Among them, three piezometers installed in the interface of colluvial and bed rock automatically recorded lots of valuable data during July of 2005 to the end of 2006. Based on records of the pore pressure varied with rainfall, normal and abnormal responses were identified and discussed. The seasonal variation of pore pressure was less than 30 kPa. During the period of heavy rainfall, the variation of pore pressure was less than 5 kPa. Besides the normal response of pore pressure increased quickly after rainfall, abnormal response was observed which the pore pressure decreased during the period of heavy rainfall. In the same period of the pore pressure dropped suddenly, the surface and subsurface displacement was also observed. Accordingly, the decreasing of pore pressure could original from the dilation in the sliding surface which induced a negative excess pore pressure. The negative excess pore pressure occurs when the rainfall intensity greater than 30mm/hr, the accumulated precipitation greater than 124mm and the duration of rainfall greater than 15 hr.
DE: 1810 Debris flow and landslides
DE: 1835 Hydrogeophysics
SC: Hydrology [H]
MN: 2007 Fall Meeting