Consolidation Integrated Buoyancy Equation for Soft Ground Improved With Lightweight Polyurethane Foam

Abstract

Consolidation settlement occurs when a saturated soil is subjected to an increase in overburden pressure that causes a volume change in the soil. When a lightweight material is used as a ground improvement, the stress is reduced as the soft soil is partially removed and replaced by the lightweight material. In addition, the improved ground with lightweight material has a potential to uplift due to the buoyancy of lightweight material. The uplift force reduces the stress imposed on the underlying soil as it acts in the upward direction, thus further reducing the consolidation settlement. This study is executed to produce an alternative equation for consolidation settlement incorporating the buoyancy effect for lightweight polyurethane (PU) foam as a ground improvement method. A Rowe Cell consolidation laboratory test was conducted on untreated marine clay soil as well as on improved marine clay with different thicknesses of lightweight PU foam. Validation of the laboratory test results was done by finite element analysis, PLAXIS 2D. The thickness of PU foam governs the buoyancy and the hydrostatic pressure of water displaced by PU foam, which is incorporated in the alternative equation. The alternative consolidation settlement equation is applicable for ground improved with lightweight polyurethane foam and found to be more economical and practical as the buoyancy is taken into account in the equation. ABSTRAK: Mendapan pengukuhan berlaku apabila tanah tepu mengalami peningkatan tekanan beban yang menyebabkan perubahan isipadu tanah. Apabila bahan ringan digunakan sebagai penambahbaikan tanah, tekanan akan berkurang kerana sebahagian tanah lembut dikeluarkan dan diganti dengan bahan ringan. Selain itu, tanah yang diperbaiki dengan bahan ringan berpotensi untuk terangkat ke atas keranan daya apung bahan ringan. Daya angkat bahan ringan mengurangkan tekanan yang dikenakan ke atas tanah kerana daya bertindak ke arah atas, dan seterusnya megurangkan mendapan pengukuhan. Kajian ini dijalankan untuk menghasilkan persamaan alternatif bagi mendapan pengukuhan dan digabungkan dengan kesan daya apung untuk busa poliuretena ringan (PU) sebagai kaedah penambahbaikan tanah. Ujian makmal mendapan pengukuhan menggunakan peralatan Rowe Cell dilakukan pada tanah liat marin yang asal serta yang diperbaiki dengan ketebalan busa PU ringan yang berbeza. Pengesahan hasil ujian makmal dilakukan dengan analisis elemen terhingga, PLAXIS 2D. Ketebalan busa PU mempengaruhi daya apung dan tekanan hidrostatik bagi kedalaman air yang disesarkan oleh busa PU dan digabungkan dalam persamaan alternatif. Persamaan alternatif mendapan pengukuhan tersebut boleh digunapakai untuk pembaikan tanah menggunakan bahan ringan busa poliuretena dan didapati menjimatkan kos dan praktikal kerana keapungan diambilkira didalam persamaan tersebut.

Analysis of Floating Mooring Buoy as Platforms at Sea

“…Therefore, the mooring buoy is also equipped with a lamp that has solar panels as a backup energy source to keep it lit at night. (Ghafari & Dardel, 2018;Lat et al, 2022;Wüest et al, 2021). The works to install buoys + ballast at sea for the lifting sinkers (concrete block weights) will be done using the floating method using a mini pontoon.…”

“…However, the most common SPM type in Indonesia is the Catenary Anchor Leg Mooring (CALM) type. (Ghafari & Dardel, 2018;Lat et al, 2022) The CALM buoy system consists of a large buoy supported by multiple strands of chain anchored to the seabed. The configuration of the CALM buoy has a howser connecting the tanker and the buoy.…”