Analysis of Slope Stability on the Katapop II Hills During Rainfall, Sorong Regency

Rokhman; Raynold Setiawan; Ahmad Januar Jafarudin; Retno Puspa Rini

doi:10.55927/ijis.v4i12.773

Authors

Rokhman Civil Engineering Muhammadiyah University of Sorong
Raynold Setiawan Civil Engineering Muhammadiyah University of Sorong
Ahmad Januar Jafarudin Civil Engineering Muhammadiyah University of Sorong
Retno Puspa Rini Civil Engineering Muhammadiyah University of Sorong

DOI:

https://doi.org/10.55927/ijis.v4i12.773

Keywords:

Slope Stability, Safety Factor, Bishop Method, Geoslope, Saturated Soil

Abstract

Majaran Village, Salawati District (Katapop II), is a hilly area characterized by high rainfall intensity, making it susceptible to slope instability. Rainfall infiltration increases soil saturation and pore water pressure, leading to a reduction in effective stress and soil shear strength, which in turn decreases the slope safety factor (SF). This study aims to evaluate and compare slope stability under saturated and unsaturated soil conditions, both with and without external loading, using a combined manual and numerical approach. Slope stability analysis was conducted using the Bishop method, applied through manual calculations and validated using GeoSlope/SLOPE-W software. The safety factor values obtained from each condition were compared to assess the influence of soil saturation and loading on slope stability. The results indicate that under unsaturated conditions, the average safety factor exceeds 2.0, whereas under saturated conditions, the safety factor decreases to an average of approximately 1.5. Although both conditions remain within the stable classification range (1.7 < SF ≤ 2.0), the observed reduction in safety factor under saturated conditions highlights the significant impact of rainfall infiltration on slope stability. Prolonged or high-intensity rainfall events may further increase instability risks. Therefore, continuous hydrogeological monitoring and appropriate slope management measures are essential to mitigate potential landslide hazards in the study area

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