Ilham, Muhammad Arifian (2026) Analisis Stabilitas Lereng Galian dengan Pendekatan Cracked Soil (Studi Kasus: Longsoran Sta 17+850 Paket Pembangunan Jalan dan Jembatan Bululawang – Sidomulyo – Tambakrejo, Kabupaten Blitar, Provinsi Jawa Timur). Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Pembangunan Jalur Lintas Selatan (JLS) merupakan Proyek Strategis Nasional yang bertujuan untuk mendukung pariwisata sepanjang Pantai Selatan Pulau Jawa. Pada STA 17+850 Ruas Bululawang–Sidomulyo–Tambakrejo, lereng galian setinggi ±30 m yang didominasi batuan gamping mengalami longsor berulang pada slope 2 dan 3, meskipun telah dilakukan regrading dari kemiringan 71,6° menjadi 45°. Analisis stabilitas lereng pada kondisi initial menunjukkan nilai SF >> 1, yang bertentangan dengan kondisi aktual longsor di lapangan. Hal ini mengindikasikan adanya mekanisme keruntuhan yang tidak dapat dijelaskan oleh pendekatan konvensional. Penelitian ini bertujuan untuk mengidentifikasi penyebab utama longsor menggunakan pendekatan cracked soil serta mengevaluasi pengaruh kemiringan lereng dan pengaruh hujan terhadap stabilitas lereng. Analisis dilakukan menggunakan Finite Element Method dengan perangkat lunak Plaxis 2D. Pendekatan cracked soil diterapkan dengan memodelkan tanah sebagai material “behaving like sand” pada kondisi drained (c = 0 dan φ = φ), yang merepresentasikan hilangnya kohesi akibat retakan sebagai jalur infiltrasi air. Dua model numerik dikembangkan, yaitu model dengan asumsi seluruh lapisan tanah kehilangan kohesi dan model dengan pemodelan retakan spesifik pada bidang gelincir. Hasil analisis menunjukkan bahwa pendekatan cracked soil mampu merepresentasikan kondisi lapangan dengan menghasilkan nilai SF < 1. Zona cracked soil pada sisipan lapisan lanau kelempungan berkerikil di antara batuan gamping serta pengaruh hujan deras diidentifikasi sebagai penyebab utama longsor. Analisis perkuatan menunjukkan bahwa soil nailing efektif sebagai penanganan permanen dengan meningkatkan nilai SF hingga 1,515.
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The construction of Trans South-South Java Road Project (TRSS) is a National Strategic Project aimed at supporting tourism development along the southern coast of Java Island. At STA 17+850 of the Bululawang–Sidomulyo–Tambakrejo section, a ±30 m high cut slope dominated by limestone experienced repeated slope failures at slopes 2 and 3, despite regrading from a slope angle of 71.6° to 45°. Initial slope stability analysis indicated a safety factor (SF) significantly greater than 1, which contradicts the actual failure conditions observed in the field. This discrepancy suggests the presence of failure mechanisms that cannot be explained by conventional approaches.This study aims to identify the primary causes of slope failure using a cracked soil approach and to evaluate the effects of slope geometry and rainfall on slope stability. The analyses were conducted using the Finite Element Method (FEM) with PLAXIS 2D software. The cracked soil approach was implemented by modeling the soil as a “behaving like sand” material under drained conditions (c = 0 and φ = φ), representing cohesion loss due to cracks acting as preferential infiltration paths. Two numerical models were developed, one assuming cohesion loss throughout all soil layers and another explicitly modeling cracks along the potential slip surface.The results indicate that the cracked soil approach successfully represents the field conditions by producing safety factors lower than 1. Cracked soil zones within interbedded gravelly clayey silt layers between limestone strata, together with the influence of intense rainfall, were identified as the main causes of slope failure. Reinforcement analysis shows that soil nailing is an effective permanent mitigation measure, increasing the safety factor to 1.515.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Stabilitas Lereng, Cracked Soil, Safety Factor, Longsoran, Plaxis 2D. Slope Stability, Cracked Soil, Safety Factor, Landslide, Plaxis 2D |
| Subjects: | T Technology > TA Engineering (General). Civil engineering (General) > TA169.5 Failure analysis T Technology > TA Engineering (General). Civil engineering (General) > TA455.S6 Soil (Materials of engineering and construction) |
| Divisions: | Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Civil Engineering > 22101-(S2) Master Thesis |
| Depositing User: | Muhammad Arifian Ilham |
| Date Deposited: | 26 Jan 2026 07:54 |
| Last Modified: | 26 Jan 2026 07:54 |
| URI: | http://repository.its.ac.id/id/eprint/130540 |
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