Peat soil is a soft soil with more than 75% organic content, very high void ratio, and very high water content. In recent times, the lack of land use has made peat soil as an option for agriculture, drainage channels, and also for construction. Utilization of peat soil usually causes the peat soil water content to decrease. Based on the condition of its water content, the condition of peat soil can be classified into several conditions, which is peat soil with constant water content, peat soil which affected by ambient water content, and dried peat soil. Some of the improvement efforts made include the method of improvement by means of stabilization. The stabilization material used was a mixture of lime (CaCO3) and rice husk ash with the combination of 70% rice husk ash and 30% lime. Based on those studies, the use of the stabilization method is not recommended if the peat soil water content has decreased more than 50%. Therefore, the peat soil water content needs to be maintained in order for the stabilization to be effective and also for the sake of environmental preservation.

ABSTRAKAnalisa stabilitas leremg digunakan untuk prediksi nilai faktor aman yang kritis dan bidang keruntuhan potensial. Pada kondisi lereng buatan akan lebih mudah dalam melakukan prediksi tersebut, sedangkan pada kondisi lereng alam perlu diperhatikan perubahan sudut kemiringan dalam satu bentuk ketinggian. Kondisi geometri lereng alam di Kediri yang curam setinggi 15 m tanpa proteksi dapat diindentifikasi bentuk lereng menjadi 2 bagian yaitu potongan AA dan potongan BB. Berdasarkan Potongan AA dan potongan BB memiliki sudut paling kecil yaitu 51,3°dan sudut kemiringan terbesar masing -masing yaitu 63.7°dan 78.7°. Pemodelan dilakukan berdasarkan bentuk lereng alam dan memodelkan dari berbagai sudut kemiringan menggunakan program bantu Geo Slope/W dengan metode Ordinary Method Of Slices (Metode Fellenius) bidang runtuh dengan asumsi entry and exit. Dari hasil pemodelan nilai, secara umum hasil yang diperoleh, dengan meninjau setiap perubahan lereng tanpa beban, menunjukkan bahwa nilai angka keamanan yang diperoleh SF > 2 dengan bidang runtuh semakin besar. Analisa stabilitas secara keseluruhan tanpa menijau setiap perubahan sudut, nilai SF pada potongan AA adalah 1,693 dan potongan BB adalah 1.504. Kemudian apabila dimodelkan dengan menganggap lereng seragam adalah dengan kemiringan lebih dari 60°nilai angka keamanan (SF) < 1 dengan lebar kelongsoran potensial pendek.Kata Kunci : manajemen aset infrastruktur, stabilitas lereng, fellenius, geo slope/w

Pembangunan konstruksi jalan raya diatas tanah ekspansif pada masa pasca konstruksi perlu ditinjau kembali kondisi metode perbaikan tanah yang digunakan. STA 86 +399 – STA 86 +400 mengalami kerusakan pada masa pasca konstruksi. Metode perbaikan tanah yang digunakan pada saat mengalami kerusakan yaitu dengan menambahkan Shear – Key di kaki timbunan. Penggunaan Shear – Key ini melengkapi metode perbaikan tanah sebelumnya dimana ada Replacement sedalam 1,5 m dengan Timbunan. Fungsi dari Shear – Key diharapkan dapat menjadi moisture barrier sehingga kondisi tanah dasar dapat terjaga kadar airnya. Shear - Key adalah pembuatan kaki di bawah kaki timbunan dengan dimensi tinggi 1,5 m dan lebar 4 m dengan material pasir halus yang dipadatkan. Pada STA 86+399 – STA 86+400 akan dilakukan analisis dari ketiga metode perbaikan. Dari hasil pemodelan menggunakan Seep/W menunjukkan bahwa besarnya rembesan yang terjadi dengan adanya Shear – Key kecil yaitu6x10-6 – 1x10-5 m/det dibandingkan tanpa Shear – Key sebesar 0.5 – 1 m/det. Sedangkan pada kondisi analisis stabilitas dengan adanya Shear – Key yang mengalami sedikit perubahan pada angka keamanan, besarnya bidang longsor dan kedalaman kelongsoran. Pengaruh perubahan muka air tanah pada analisis stabilitas menggunakan Shear –Key bila MAT dicoba pada kedalaman 1,0 m nilai angka kemanan turun hingga ± 4% dibandingkan tanpa menggunakan Shear – Key. Perubahan angka kemananan yang terjadi masih dikategorikan aman karena nilai SF 1.5 dengan penggunaan kombinasi perbaikan replacement, timbunan dan Shear – Key pada masa Konstruksi.

Landslide one of the natural disasters that caused many victims. Therefore, the landslide need a construction that can withstand landslide force. This study aims to plan retaining walls to prevent landslides in the farm area in Kandangan Subdistrict, Kediri Regency. The method used is to use slide analysis which is used to plan the retaining wall. In addition the planning of soil containment walls u ses several methods as a comparison. The results of this study indicate that the planning of ordinary soil retaining walls is still not enough to overcome slides. The minimum SF value that meets the safe limit of landslide prevention is 1.541 in the combination of 1/3 H terracing and the number of gabions as many as 7 with a total height of 2- 3 m .

The design on expansive soils can easily change in volume due to the influence of water content. This makes it necessary to consider soil improvement methods in the planning process to maintain the variation in the water content. One of these methods includes chemical stabilization, which is carried out by adding materials such as cement or lime. In expansive soils, stabilization efforts aim to reduce the plasticity index and increase the shear strength parameters. Therefore, this study focused on the addition of slaked lime (Ca(OH)2) to expansive soil in Lakarsantri, Surabaya. The stabilizing materials used contain calcium to form pozzolan in the clay and increase the bearing capacity parameter, which is variation in shear strength. The soil was taken at 2 points A and B with a different moisture content of 48.57% and 35.12%, as well as a high plasticity index value > 50% using a percentage (Ca(OH)2) of 6%-24% at a certain curing time. Based on the results, the plasticity index in the soil changed from very high to moderate with an optimum percentage value of 6% at 30 days of curing time. The optimum value of soil shear strength is (Ca(OH)2) 6% at 30 days of age in soil A, the cohesion value is 0.02 kg/cm2, and an internal shear angle of 36°. In soil B, the optimum shear strength obtained (Ca(OH)2) was 6% at the age of 10 days with a cohesion value of 0.14 kg/cm2 and an internal shear angle of 23.80°. Therefore, the results of this study show that the parameter of shear strength of the soil from the cohesion value showed that the cohesion value decreased with the addition of Ca(OH)2, while the internal shear angle increased.