Table 6. Result of borehole investigation.

No.	Stratigraphy	Depth(GL.−m)	Thickness(m)	Composition	N(TCR/RQD)
BH-1	Topsoil layer	0.0 ~ 1.4	1.4	Silty sand with rock fragment, Dense	47/30
	Weathering soil	1.4 ~ 6.5	5.1	Silt with rock fragment, Coagulate	50/25 ~ 50/22
	Soft rock	6.5 ~ 11.4	4.9	Shale, Severe weathering, Severe crack	(64~65/0~5)
	Slickensides	11.4 ~ 30.4	19.0	Shale, little ~ normal weathering, little ~ normal Crack	(96~100~60/95)
BH-2	Topsoil layer	0.0 ~ 0.5	0.5	Silty sand with rock fragment,	-
	Weathering soil	0.5 ~ 1.5	1.0	Silt with rock fragment, Solidity	14/30
	Soft rock	1.5 ~ 9.5	8.0	Shale, little ~ normal weathering, Normal ~ Severe Crack	(83~100/20~37)
	Slickensides	9.5 ~ 15.5	6.0	Shale, normal~severe weathering, Normal ~ Severe Crack	(100/58~63)