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2026 Vol.27, Issue 10 Preview Page
Evaluation of Horizontal-Drain Performance and Rainfall-Induced Slope Stability Using Coupled Hydro-Mechanical Analysis

수리-역학 연계해석을 이용한 강우침투 비탈면의 수평배수공 배수성능 및 안정성 평가

Hoki Ban1
,
Heesu Kim2
,
Jaemo Kang3*
반 호기1
,
김 희수2
,
강 재모3*
1Professor, Dept. of Civil Engineering, Kangwon National University
2Post-Doctoral Researcher, Dept. of Civil Engineering, Kangwon National University
3Research Fellow, Department of Geotechnical Engineering Research, Korea Institute of Civil Engineering and Building Technology
*Corresponding Author
1 October 2026. pp. 45-51
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Abstract

This study investigated the influence of horizontal-drain inclination on rainfall-induced drainage and the stability of an initially unsaturated slope without an initial groundwater table. Coupled hydro-mechanical finite-element analyses were performed to account for the interaction between pore-water-pressure evolution and soil deformation during rainfall infiltration. The drain was represented as a continuous high-permeability zone that collected infiltrating water from the surrounding ground. Cases without a drain and with upward drain inclinations of 0°, 5°, and 10° were compared. During six days of sustained rainfall, the cumulative discharges were 2.394, 3.367, and 3.391 m3/m for the 0°, 5°, and 10° cases, respectively. The maximum pore-water pressure at the end of rainfall decreased from 41.0 kPa without a drain to 30.1, 24.9, and 24.4 kPa for the 0°, 5°, and 10° cases, respectively. The factor of safety was identified as the strength-reduction factor at the onset of a pronounced nonlinear increase in maximum displacement, corroborated by the formation of a continuous band of equivalent plastic strain. The resulting factors of safety were 1.63, 2.13, 2.61, and 2.64 for the cases without a drain and with drain inclinations of 0°, 5°, and 10°, respectively. Relative to the horizontal drain, the 5° upward drain intercepted a larger portion of the wetted zone, increased discharge, reduced pore-water pressure, and suppressed slope deformation. The drainage and stability responses of the 5° and 10° cases were similar, indicating that the additional benefit of increasing the inclination beyond 5° was limited under the conditions considered.

Keywords
Horizontal drain
Rainfall infiltration
Coupled hydro-mechanical analysis
Unsaturated slope
Strength reduction method

본 연구에서는 초기 지하수위가 없는 불포화 토사 비탈면을 대상으로 수평배수공의 설치각도가 강우 침투수의 배출과 비탈면 안정성에 미치는 영향을 평가하였다. 강우 침투에 따른 간극수압과 변형의 상호작용을 고려하기 위하여 간극수압과 변위를 동일 시간증분에서 산정하는 수리–역학 연계 유한요소해석을 수행하였다. 배수공은 주변 지반의 침투수를 집수하는 고투수성 연속 배수영역으로 모델링하였으며, 배수공 미설치 조건과 설치각도 0°, 5° 및 10° 조건을 비교하였다. 그 결과, 6일간의 지속강우 동안 누적 배수량은 0°, 5° 및 10° 조건에서 각각 2.394, 3.367 및 3.391 m3/m로 나타났다. 강우 종료 시 최대 간극수압은 배수공 미설치 조건의 41.0 kPa에서 0°, 5° 및 10° 조건의 30.1, 24.9 및 24.4 kPa로 감소하였다. 변위가 급격히 증가하기 시작한 강도감소계수는 각각 1.63, 2.13, 2.61 및 2.64로 평가되었다. 5° 상향 설치는 수평 설치보다 침윤영역과 배수공의 중첩범위를 확대하여 배수량을 증가시키고 비탈면의 변형을 억제하였다. 그러나 5°와 10° 조건의 배수량, 간극수압 및 안전율 차이는 크지 않았다. 이 결과는 완만한 상향각이 배수공의 집수효율을 높일 수 있으나, 일정 각도 이후의 추가적인 안정성 개선은 제한적임을 나타낸다.

키워드
수평배수공
강우 침투
수리–역학 연계해석
불포화 비탈면
강도감소법
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Information
  • Publisher :Korean Geo-Environmental Society
  • Publisher(Ko) :한국지반환경공학회
  • Journal Title :Journal of the Korean Geo-Environmental Society
  • Journal Title(Ko) :한국지반환경공학회 논문집
  • Volume : 27
  • No :10
  • Pages :45-51
  • Received Date : 2026-09-07
  • Revised Date : 2026-09-08
  • Accepted Date : 2026-09-17
  • DOI :https://doi.org/10.14481/jkges.2026.27.10.45
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