HR: 0800h
AN: NS31B-02 [Abstracts]
TI: Assessment Ground Safety Using Time Lap Vertical Gravity Gradient At The Subsidence Area
AU: * Rim, H B
EM: rhr@kigam.re.kr
AF: Korea Institute of Geoscience and Mineral Resources, 30 Gajeong-dong, Yuseong-gu,
Daejeon, Korea, DAEJEON, 305-350, Korea, Republic of
AU: Park, Y
EM: yspark@kigam.re.kr
AF: Korea Institute of Geoscience and Mineral Resources, 30 Gajeong-dong, Yuseong-gu,
Daejeon, Korea, DAEJEON, 305-350, Korea, Republic of
AU: Lim, M
EM: limmt@rock25t.kigam.re.kr
AF: Korea Institute of Geoscience and Mineral Resources, 30 Gajeong-dong, Yuseong-gu,
Daejeon, Korea, DAEJEON, 305-350, Korea, Republic of
AU: Koo, S B
EM: sbkoo@kigam.re.kr
AF: Korea Institute of Geoscience and Mineral Resources, 30 Gajeong-dong, Yuseong-gu,
Daejeon, Korea, DAEJEON, 305-350, Korea, Republic of
AU: Kwon, B D
EM: bdkwon@mantle.snu.ac.kr
AF: Department of Earth Sciences Education, Seoul National University, San 56-1, Sillim-dong,
Gwanak-gu, Seoul, KOREA, SEOUL, 151-742, Korea, Republic of
AB:
We have carried out time-lap vertical gravity gradient (VGG) survey in order to assess the ground safety before and
after grouting. The target area is new pavement through the rice field, and the area has subsidence problems
because of excessive pumping for agricultural irrigation. Therefore, it has been reinforced with cement grouting
avoiding subsidence. In this paper, we examined the change of subsurface density distribution due to cement
grouting by means of VGG survey. VGG method is more sensitive to detect the change of near surface than gravity
survey itself because VGG enhanced small variation of gravity anomaly. We gathered one line gravity data about
270m long at every 2m. VGG survey consisted of observations between the ground bottom and the top separated
vertically about 1.5m with help of the ladder specially designed. According to result, VGG anomaly made the
response of man-made waterway clearer than Bouguer anomaly in the middle part of the line. And VGG result
showed changes of subsurface density distribution after grouting.
DE: 0920 Gravity methods (1219)
DE: 1217 Time variable gravity (7223, 7230)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly