목차
ABSTRACT 1
1. 서론 1
2. 연구대상지역 2
3. 수치해석 5
4. 지반함몰현상의 순차적 발생순서 분석 8
5. 결론 9
참고문헌 9
Table 1. Classification of soil and rock layers of the site obtained from borehole samples before initial excavation work and after ground sinking 3
Table 2. Inputs of hydrological parameters for numerical analysis of groundwater flow 6
Table 3. Precipitation recharge rate estimated on various land-use types(Kim et al., 2001) 6
Fig. 1. Location of the site of interest in Yongsan, boreholes for geotechnical field investigation before & after the ground sinking (BH, NBH), observation well (OW), and sewage box 2
Fig. 2. Results of geotechnical investigation conducted after ground sinking and before excavation 3
Fig. 3. Comparison of SPT results at BH and NBH in the vicinity of ground sinking 3
Fig. 4. Leakage water under the slab of sewage box 4
Fig. 5. Changes of groundwater level at observation wells (OW-1, 2 in Fig. 1) during site excavation 4
Fig. 6. Leakage water and soil grains at the toe of cut-off wall in the excavation site 4
Fig. 7. Soil and gravel escaped through the toe of cut off wall and deposited 4
Fig. 8. Composition of mesh, boundary condition, analysis viewpoint and subsurface stata for numerical analysis 5
Fig. 9. Results of calibration work at the observation wells in Fig. 1 before and after excavation of sandy gravel (GP) layer 7
Fig. 10. Variation of groundwater level and the distribution of total head equipotential before and after the excavation of the sandy gravel layer(Strata refer to Fig. 8-b) 7
Fig. 11. Safety factor against piping for changes of hydraulic conductivity of sandy gravel layer 8
Fig. 12. Safety factor against piping with respect to the changes of the hydraulic conductivity of the cut-off wall 8
Fig. 13. Safety factor against piping according the the variation of precipitation groundwater recharge rate 8