<![CDATA[Abstrak. Tanah lunak sebagai tanah dasar fondasi di bawah konstruksi embankment sering menimbulkan permasalahan dalam hal stabilitas dan penurunan. Oleh karena itu, perlu dilakukan perbaikan kondisi tanah lunak sebagai tanah dasar fondasi. Salah satunya menggunakan perkuatan geogrid di bawah embankment dan drainase vertikal. Penelitian ini bertujuan untuk mengetahui pengaruh penggunaan geogrid dan drainase vertikal terhadap perilaku tanah dasar fondasi berupa tanah lunak. Penelitian berdasarkan analisis metode elemen hingga dengan menggunakan program Plaxis versi 8.2. Konstruksi embankment dimodelkan dua dimensi pada kondisi plane strain, model material Mohr-Coulomb dan tipe material undrained. Geogrid dimodelkan sebagai geogrid elemen, model bidang pertemuan antara tanah dan geogrid adalah rigid embankment dan interface embankment. Drainase vertikal dimodelkan sebagai drain dengan kelebihan tekanan air pori ditetapkan nol. Hasil analisis numeris terhadap normal embankment menggambarkan bahwa perpindahan maksimum arah vertikal saat ketinggian embankment mencapai H=3,1 m adalah sebesar 0,827 m (dalam bentuk penurunan) dan arah horisontal 0,203 m, sedangkan tegangan efektif sebesar 29,38 kN/m2. Penggunaan perkuatan geogrid dan drainase vertikal pada konstruksi normal embankment dengan model interface reinforced embankment dapat mempercepat proseskonsolidasi hingga 99%, mereduksi perpindahan horisontal hingga 40,5% dan meningkatkan tegangan efektif hingga 35,9%.Abstract. Soft soil as the sub base under/beneath construction of embankment often appears the problem of the stability and the settlement. Therefore, it is necessary to improve the soft soil as the sub base. One of that is using geogrid reinforcement beneath of embankment and the vertical drain in soft soil. This research isaimed to investigate the influence of using geogrid and vertical drains to the behaviour of the sub base which is soft soil. This research based on the finite element analysis by using Plaxis v.8.2. The contruction of embankment was modelled in 2D condition of plane strain, with Mohr-Coulomb material model and undrained material type. Geogrid was modelled as element geogrid, and the contact plane between soil and geogrid was modelled as rigid and interface embankment. The vertical drains was modelled as a drain with excess pore water pressure was specified at zero value. The result of numerical analysis at normal embankment demonstrated that the maximum vertical displacement, when the height of embankment 3,1 m was 0,827 m at vertical direction (manifested as settlement) and the horizontal displacement at this height is 0,203 m, while the effective stress was 29,38 kN/m2. The use of the geogrid and vertical drains at the normally embankment, which is modeled as interface reinforced embankment can accelerate the consolidation process by 99%, to reduce the horizontal displecement by 40,5% and to increase of the effective stress by 35,9%.]]>
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