Perbaikan Tanah Dasar Menggunakan Pre-Fabricated Vertical Drain Dengan Variasi Kedalaman Dan Perkuatan Lereng Dengan Turap. Studi Kasus : Lapangan Penumpukan Peti Kemas, Pelabuhan Trisakti, Banjarmasin, Kalimantan Selatan

Metode perbaikan tanah dasar menggunakan preloading yang dikombinasikan dengan Pre-fabricated Vertical Drain (PVD) dipilih untuk proyek pengembangan lapangan penumpukan peti kemas di Pelabuhan Trisakti, Banjarmasin, Kalimantan Selatan. Tujuan menggunakan preloading adalah meningkatkan daya dukung tanah di area lapangan penumpukan dan menghilangkan pemampatan yang terjadi; pemasangan Pre-fabricated Vertical Drain (PVD) diarahkan untuk mempersingkat waktu pemampatan. Selama masa preloading, ternyata kelongsoran selebar 37 meter terjadi di area penumpukan. Namun, konstruksi tetap dilanjutkan hingga selesai. Saat beroperasi, lapangan penumpukan mengalami penurunan. Akibatnya, perkerasan lapangan penumpukan mengalami retak, bergelombang, dan hancur. Oleh karena itu, analisis ulang perencanaan perlu dilakukan. Diketahui bahwa kelongsoran terjadi saat preloading setinggi 4,0 meter. Agar lapangan penumpukan dapat beroperasi kembali, diperlukan perencanaan untuk perkuatan lereng dan untuk menghilangkan pemampatan tanah dasar di area lapangan penumpukan. Perbaikan tanah dasar menggunakan preloading yang dikombinasikan dengan Pre-fabricated Vertical Drain (PVD) digunakan untuk Zona 3, 4, dan 5, dan perkuatan lereng dengan turap digunakan untuk Zona-1 dan Zona-2 yang merupakan bagian lereng dari lapangan penumpukan. Direncanakan PVD dipasang pada kedalaman yang berbeda: 1/3H, 2/3H, dan H (H adalah ketebalan lapisan tanah lunak) untuk melihat kondisi yang menghasilkan biaya paling murah. Ketika PVD tidak dipasang sedalam tanah lunak, itu berarti pemampatan tidak dihilangkan seluruhnya sebelum lapangan penumpukan dioperasikan; akibatnya, perlu dilakukan overlay pada lapangan penumpukan secara berkala untuk menjaga tinggi permukaan tanah tetap sama. Ketika PVD dipasang sedalam tanah lunak, tidak akan terjadi pemampatan yang berarti tidak diperlukan overlay. Dari hasil perencanaan yang dilakukan, diketahui bahwa turap yang digunakan adalah Corrugated Concrete sheet pile type W-600 A1000. Turap dipasang sedalam 18 meter di Zona-1 dan sedalam 22 meter di Zona-2; selain itu, angker dipasang pada turap untuk meningkatkan kekakuan turap. Hasil perencanaan juga menunjukkan bahwa biaya yang paling ekonomis adalah PVD dipasang sampai 2/3H di Zona-3, dan tanpa PVD di Zona-4 dan Zona-5. Total biaya konstruksi adalah sebesar Rp 843.106.053,00 untuk Zona-1 dan Zona-2; Rp 9.446.530.597,00 untuk Zona-3; Rp 1.869.613.200,00 untuk Zona 4; dan Rp 3.577.392.000,00 untuk Zona 5. ==================================================================================================================Ground Improvement method using preloading combined with prefabricated vertical drain (PVD) was chosen for the container yard development project at Trisakti port, Banjarmasin, South of Kalimantan. The purpose of using preloading is to improve the soil bearing capacity at the container yard area and to eliminate its settlement; the installment of prefabricated vertical drain (PVD) was directed to shortened the time interval of soil settlement. During the preloading period, unfortunately, slope failure as wide as 37 meters took place in the container yard area. The container yard construction, however, was still carried out until finish. When it was operated, the container yard has undergone settlement. As a result, the rigid pavement of the container yard was crack, waviest, and completely destroy. Due to this problem, reanalyzing of the design had to be carried out. It was figured out that slope failure occurred when the preloading reached 4.0 meters high. In order to make the container yard can be operated, it is very important to redesign the slope retaining structure and to eliminate the settlement of soil in the container yard area. Ground improvement using preloading combined with prefabricated vertical drain (PVD) is chosen for Zona 3, 4, and 5, and slope retaining structure with sheet pile is for Zona-1 and Zona-2 as the slope part of the container yard. It is designed that PVD is installed at different depth: 1/3H, 2/3H, and H (H is thickness of soft soil layer) in order to see which one that gives the cheapest price. When the PVD is not installed until the whole thickness of soft soil layer, it means that the settlement is not eliminated completely before the container yard is operated; consequently, the container yard has to be overlay periodically in order to keep the surface elevation is always the same. When the PVD installed until the whole layer of soft soil layer, no more settlement will occur that means no overlay needed. From the design carried out, it is found that sheet pile used for slope retaining structure is Corrugated Concrete sheet pile type W-600 A1000. Sheet piles are installed at 18.0meters depth in Zona-1 and 22.0meters depth in Zona-2; besides, ground anchors are installed at the sheet piles to increase their stiffness. The designed result also shows that the most economic one is PVD has to be installed until 2/3H in Zona-3, and no PVD needed in Zona-4 and Zona-5. The total cost for construction is IDR 843.106.053,00 for Zona-1 and Zona-2; IDR 9.446.530.597,00 for Zona-3; IDR 1.869.613.200,00 for Zona-4; and IDR 3.577.392.000,00 for Zona-5