Browse > Article

A Study on the Slope Analysis of Weathered Limestone Soils during Rainfalls  

Kim Jong-Ryeol (Dept. of Civil Engineering, Chonnam National University)
Kang Seung-Goo (Dasan Engineering Co. Ltd.)
Kang Hee-Bog (Dept. of Civil & Environmental Engineering, Hanyeong College)
Park Seung-Kyun (Namyang Construction Co. Ltd.)
Park Chol-Won (Jeollanam-do Provincial)
Publication Information
The Journal of Engineering Geology / v.15, no.1, 2005 , pp. 9-17 More about this Journal
Abstract
A set of soil samples were picked up from a failed slope formed by rainfall in limestone zone in Jangseong-gun, Jeonnam, Korea, to find out its physical and mechanical characteristics for this study, and variation of safety factor depending on slope inclination was defined by analysing slope stability affected by rainfall. Decomposed limestone soil in the research area is composed of quartz, orthoclase, gibbsite, geothite, etc., with specific gravity of 2.73, and this soil is included in SC by unified soil classification system. Calcium ingredient decreased remarkably during weathering at its mother rock. Coefficient of permeability is 2.56×10/sup -4/ cm/ sec, similar to its value of silty clay. Cohesion decreases remarkably from 3.0 t/ ㎡ to 0.72 t/ ㎡, and Φ value of internal friction angle tends to decrease as it turns to be saturated soil from partial saturated soil in the shear test. To analyze slope stability affected by rainfall, it is reasonable to seek seepage depth with reference to rainfall＊ intensity. In the slope stability analysis, when the seepage depth is the larger, its safety factor is the less, which makes the slope unstable. Comparing with minimum safety factor, 1.5 of cut slope in consideration of the seep-age line, safety factor is found to be satisfactory only when inclination of cut slope of decomposed limestone soil is more than 1：1.2 slope at least considering rainfall. It is also found that decrease of cohesion has great effect on decline of safety factor of slope while partial saturated soil turns to be saturated soil.
Keywords
weathered limestone; cohesion; internal friction angle; seepage depth;
Citations & Related Records
연도 인용수 순위
  • Reference
1 김기영, 1995, 혈암풍화토의 전단특성에 관한 연구, 경북대학교 석사학위논문
2 김영수, 이상복, 정성관, 1995, 퇴적암 풍화토의 공학적 특성-대구․경북지역을 중심으로, 한국지반공학회지. v.11(4), pp.63-74
3 김재홍 외 3명, 2002, 강우 시 습윤에 의한 불포화 풍화 토의 사면안정해석 연구, 한국지반공학회지, 제 18 권, 제 2호, pp 123-136
4 이영수, 1983, 화강풍화토의 파쇄 및 다짐에너지가 투수성에 미치는 영향, 대한토목학회지, v.3(3), pp.107-116
5 오재화, 이광찬, 2003, 실내시험에 의한 붕괴사면 경계 면의 전단강도 특성, 대한토목학회지, v23(6), pp.373-381
6 Pradel, D. and Raad, G. 1993, Effect of permeability on surficial stability of homogeneous slopes, J. Geotechnical Engineering, ASCE, Vol.119(2), pp.315-332   DOI
7 박병기, 1998, 한국화강토의 토목공학적 특성연구, 한 국과학재단, pp.10-54
8 이상복, 1994, 혈암풍화토의 공학적 특성 연구-대구 앞산 지역을 중심으로, 경북대학교 석사학위논문
9 이선주, 2001, 강우 시 사면의 침투거동에 관한 연구, 홍익대학교 석사학위논문
10 Green, W. H., and Ampt, G. A.,1911, Studies of soil physics I. The flow of air and water through soils, J. Agr. Sci., 4, pp.1-24   DOI   ScienceOn
11 Brooks, R. H. and Corey, A. T.,1964, Hydraulic properties of porous media, Hydrology paper No.3, Civil Eng. Department, Colorado State University, Fort Collins
12 안일환, 2001, 강우 침투 시 얕은 파괴가 발생하는 토사 사면에 대한 안정해석, 경기대학교 석사학위 논문
13 건설교통교부, 2000, 한국 확률강우량도 작성, 1999년 도 수자원 관리기법 개발 연구조사 보고서, V. 1, pp 94-154