Wibowo, Marthen Riyandi (2026) Analisis Stabilitas Dan Penanganan Alternatif Kelongsoran Lereng Galian Pada Jalan Tol Padang-Sicincin. Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Jalan Tol Padang–Sicincin Melintasi Topografi Perbukitan Yang Menuntut Pekerjaan Galian Lereng, Sehingga Berpotensi Menimbulkan Kelongsoran Yang Mengancam Keselamatan Konstruksi Dan Keandalan Infrastruktur. Pada Lokasi STA 32+450 Dijumpai Indikasi Keruntuhan Lereng Galian Pada Material Pasir Lepas. Penelitian Ini Bertujuan Untuk Mengidentifikasi Penyebab Kelongsoran Beserta Parameter Tanah Yang Paling Berpengaruh, Menganalisis Alternatif Desain Penanganan Sesuai Kriteria Desain, Serta Menentukan Alternatif Penanganan Yang Paling Tepat Pada Lokasi Tersebut. Analisis Dilakukan Menggunakan Data Sekunder Penyelidikan Tanah Berupa Bor Log, Uji Standard Penetration Test (SPT), Dan Uji Laboratorium. Evaluasi Stabilitas Lereng Dilaksanakan Dengan Metode Elemen Hingga Dua Dimensi Menggunakan Perangkat Lunak PLAXIS 2D Dan Diverifikasi Melalui Perhitungan Analitis, Baik Pada Kondisi Eksisting Maupun Pada Lima Alternatif Penanganan, Yaitu Soil Nailing, Secant Pile, Secant Pile Dengan Ground Anchor, Secant Pile Dengan Penyesuaian Alinyemen, Dan Struktur Portal (Box Traffic). Pemilihan Alternatif Terbaik Ditetapkan Melalui Metode Simple Additive Weighting (SAW) Dengan Mempertimbangkan Aspek Kesesuaian Desain, Sumber Daya, Pelaksanaan, Waktu, Dan Biaya. Hasil Analisis Menunjukkan Bahwa Kelongsoran Disebabkan Oleh Ketidaksesuaian Mendasar Antara Geometri Galian Rencana (Vertikal : Horizontal = 3 : 1 ±71,6° Dan Kapasitas Geser Material Loose Sand (N-SPT 6–7; = 28°–30°), Sehingga Gaya Pendorong Akibat Berat Sendiri Tanah Melampaui Tahanan Gesernya Dan Massa Tanah Tidak Mampu Mempertahankan Kesetimbangan. Kondisi Tersebut Diperberat Oleh Kontras Kekakuan Antarlapisan Serta Efek Unloading Akibat Penggalian Bertahap Yang Menurunkan Faktor Keamanan Dari 1,07 Pada Kondisi Eksisting Menjadi 0,8152 Pada Tahap Galian Keempattanpa Adanya Penanganan Khusus. Parameter Tanah Yang Paling Menentukan Adalah Sudut Geser Dalam () Serta Kepadatan Dan Kekakuan Lapisan Loose Sand. Pada Proses Evaluasi Seluruh Alternatif, Semua Alternatif Memenuhi Kriteria Desain, Yaitu Faktor Keamanan (SF) ≥ 1,50 Pada Kondisi Layan Dan ≥ 1,10 Pada Kondisi Gempa, Dengan Hasil PLAXIS 2D Berkisar Sebesar 1,52–1,82 Pada Kondisi Layan Dan 1,16–1,37 Pada Kondisi Gempa. Berdasarkan Penilaian Metode Simple Additive Weighting (SAW), Penanganan Alternatif Dengan Soil Nailing Memperoleh Nilai Preferensi Tertinggi (0,97) Dan Ditetapkan Sebagai Alternatif Yang Paling Tepat Karena, Selain Memenuhi Kriteria Stabilitas, Unggul Dalam Kemudahan Pelaksanaan, Waktu Pelaksanaan Tersingkat, Dan Biaya Paling Ekonomis.
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The Padang–Sicincin Toll Road traverses hilly terrain that necessitates slope excavation, thereby creating the potential for slope failure that threatens construction safety and infrastructure reliability. At location STA 32+450, indications of excavation slope failure were identified within loose sand material. This study aims to identify the causes of the slope failure and the most influential soil parameters, to analyze alternative stabilization designs in accordance with the design criteria, and to determine the most appropriate stabilization alternative at the site. The analysis employed secondary soil-investigation data comprising borehole logs, the Standard Penetration Test (SPT), and laboratory tests. Slope stability was evaluated using the two-dimensional finite element method with PLAXIS 2D software and verified through analytical calculations, for the existing condition and five stabilization alternatives: soil nailing, secant pile, secant pile with ground anchor, secant pile with alignment adjustment, and a portal structure (box traffic). The best alternative was determined using the Simple Additive Weighting (SAW) method, considering design suitability, resources, constructability, time, and cost. The results show that the slope failure was caused by a fundamental mismatch between the planned excavation geometry (Vertical : Horizontal = 3 : 1, ±71.6°) and the shear capacity of the loose sand (N-SPT 6–7; = 28°–30°), such that the driving force arising from the soil’s self-weight exceeded its shear resistance and the soil mass could not maintain equilibrium. This condition was aggravated by the stiffness contrast between soil layers as well as the unloading effect of staged excavation, which reduced the safety factor from 1.07 in the existing condition to 0.8152 at the fourth excavation stage in the absence of any dedicated stabilization measure. The most decisive soil parameters are the internal friction angle () and the density and stiffness of the loose sand layer. In the evaluation of all alternatives, every alternative satisfied the design criteria, namely a safety factor (SF) ≥ 1.50 in the service condition and ≥ 1.10 in the seismic condition, with PLAXIS 2D results ranging from 1.52–1.82 in the service condition and 1.16–1.37 in the seismic condition. Based on the assessment using the Simple Additive Weighting (SAW) method, the soil nailing alternative obtained the highest preference value (0.97) and was established as the most appropriate alternative because, in addition to satisfying the stability criteria, it excels in constructability, has the shortest construction time, and offers the most economical cost.
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