ANALISIS PERILAKU TIMBUNAN DENGAN PERKUATAN GEOSINTETIK MENGGUNAKAN SOFTWARE PLAXIS

Sito Ismanti, Prof(ret). Dr. Ir. Kabul Basah Suryolelono, Dip.H.E., D.E.A.

2012 | Tesis | S2 Teknik Sipil

Permasalahan pada struktur timbunan badan jalan di atas tanah lunak dengan muka air tinggi membutuhkan solusi praktis dan efektif. Beban operasional yang besar, kondisi tanah dasar terendam, dan proses konsolidasi menyebabkan ketidakstabilan dan membahayakan badan jalan. Perkuatan bahan geosintetik diharapkan mampu menjadi solusi terbaik. Kestabilan struktur tanah timbunan yang diperkuat dipengaruhi oleh pembuatan desain berdasarkan analisis keruntuhan, pemilihan perkuatan yang sesuai, kontrol di lapangan selama pemasangan, pelaksanaan penimbunan dan perawatan. Analisis meninjau perilaku tegangan regangan geosintetik dan analisis angka aman tanah timbunan ruas Jalan Tol Semarang – Solo Tahap I di Ruas Semarang – Bawen Seksi I: Tembalang – Gedawang didasarkan pada metode elemen hingga menggunakan software PLAXIS. Tanah dan geosintetik merupakan material non linear elastoplastis, dimodelkan 2D plane strain dengan model Mohr Coulomb. Struktur tanah dibagi menjadi elemen-elemen segitiga, dan elemen garis untuk geosintetik. Data validasi menggunakan durasi konsolidasi. Perbandingan dilakukan antara timbunan tanpa dan dengan perkuatan. Analisis dilakukan dengan variasi kekuatan dan nilai interface berdasarkan jenis bahan perkuatan. Beban lalu lintas dan gempa disimulasikan untuk mengetahui kestabilan timbunan pada kondisi operasional. Kapasitas dukung tanah dasar pada struktur tanah timbunan ini sebesar 1035,52 kN/m2, dibandingkan dengan dengan beban, tanah dasar mampu menerima beban timbunan setinggi 4 meter, namun penimbunan dilakukan bertahap untuk kemudahan pelaksanaan. Data validasi menggunakan hasil hitungan durasi konsolidasi yaitu selama 164,76. Geosintetik mampu menggantikan kekuatan tanah yang lemah selama konsolidasi berlangsung atau ketika tegangan air pori yang meningkat ketika penimbunan dilakukan, namun tidak mereduksi penurunan total akibat beban timbunan. Variasi normal stiffness dan interface berdasarkan jenis bahan dan manufacturing process sangat mempengaruhi hasil analisis. Dalam penelitian ini, perkuatan jenis geotekstil woven mampu mengandalkan kemampuan tarik dan regangan bahannya serta meningkatkan angka aman yang signifikan yaitu dari 1,27 untuk timbunan tanpa perkuatan menjadi 1,35.

The problems on the road embankment soil structure located above the soft soil with high water table require practical and effective solutions. The high operational loading and the soft base soil with its soaked condition causing nonuniform settlement which endanger the stabilization of the road. Geosynthetic reinforcement expected to be the best solution by relying on the ability of tensile strength. Stability of reinforced embankment structure influenced by several aspects, namely the design based on the collapse analysis and selection of appropriate reinforcing material, control in field either during the installation of reinforcing materials, stockpiling and maintenance for a certain period. This analysis reviewed stress-strain behavior of geosynthtic as reinforcement and safety factor analysis that happens to construction of embankment Toll Road Semarang – Solo especially on the Stage I in Part Semarang – Bawen Section I: Tembalang – Gedawang based on finite element method using software PLAXIS. The soil and geosynthetiic modeled two dimensional as plane strain with Mohr – Coulomb material model as elastoplastic non linear. Comparison made between embankment with and without reinforcement to determine the effectiveness of the geosynthetic use. This analysis was done with variations of the reinforcement strength and value of interface based on variations of geosynthetic type. Traffic load and earthquake simulated to determine the stability of embankment on the operational condition. The bearing capacity of subgrade in this construction equals to 1035,524 kN/m2. It is compared with the embankment load, the subgrade is capable of receiving 4 meters of embankment height, but the embankment carried out in stages to easier implementation. 164,76 days as result of the duration consolidation is used as a validation data of the finite element analysis. Installation of reinforcement can replace the low shear strength when consolidation process or during increasing of pore water pressure, but did not reduce total settlement due to the embankment load. Variations in the value of normal stiffness and an interface based on the variations of materials type greatly influence the results of the analysis and output of the PLAXIS software. In this study, geotextile non woven reinforcement able to rely on the stability stress and strain of the material as well as increase the safety factor significantly, from 1,27 as safety factor of embankment without reinforcement to 1,35.

Kata Kunci : timbunan badan jalan, perkuatan geosintetik, metode elemen hingga