Wahana Teknik Sipil: Jurnal Pengembangan Teknik Sipil
Vol. 31 No. 1 (2026): Wahana Teknik Sipil

NUMERICAL ANALYSIS OF POST RAINFALL SLOPE STABILITY WITH REINFORCEMENT CASE STUDY IN PURWOSARI KULON PROGO

Yuli Fajarwati (Universitas Negeri Yogyakarta)
Zalfa Nabila (Universitas Negeri Yogyakarta)
Dian Eksana Wibowo (Universitas Negeri Yogyakarta)
Endaryanta Endaryanta (Universitas Negeri Yogyakarta)



Article Info

Publish Date
17 Jun 2026

Abstract

Continuous rainfall over several days caused a landslide along Jalan Penggung, Purwosari Village, Girimulyo District, Kulon Progo Regency. This study was conducted to analyse slope stability under rainfall conditions and to evaluate reinforcement alternatives including soil nailing, ground anchors, and gabions. The slope topography was obtained from DEMNAS data and processed using AutoCAD Civil 3D, while soil parameters were derived from laboratory testing. Rainfall data were obtained from the JAXA satellite and effective rainfall infiltration was calculated using the SCS-CN method. The infiltration was modelled using SEEP/W and the slope stability was subsequently analysed using SLOPE/W with and without reinforcement. The analysis of the existing slope without seismic loading produced an initial safety factor (SF) of 0.922, which decreased to 0.801 after one day of rainfall. When seismic loading was considered, the initial SF was 0.639 and further decreased to 0.550 after one day. These results indicate that the existing slope is unsafe under both static and seismic conditions, making reinforcement necessary. The SF of the slope increased by 118% with soil nailing, 128% with anchors, and 14% with gabions under static conditions. Under seismic loading, soil nailing increased the SF by 101%, anchors by 110%, and gabions by 15%. These findings demonstrate that soil nailing and anchors can improve slope stability to safe levels, whereas gabions are ineffective for the studied slope conditions.

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Journal Info

Abbrev

wahana

Publisher

Subject

Civil Engineering, Building, Construction & Architecture Earth & Planetary Sciences Engineering Transportation

Description

Wahana Teknik Sipil: Jurnal Pengembangan Teknik Sipil or Civil Engineering Forum: Journal of Civil Engineering Development is a medium of communication and dissemination of research results, case studies, and scientific reviews (applied) to scientists and practitioners in the field of Civil ...