EVALUASI PENGARUH JARAK DAN POLA DOWNHOLE DEEP COMPACTION (DDC) SETTLEMENT 6 PADA GROUND IMPROVEMENT RUNWAY PROYEK DHOHO INTERNATIONAL AIRPORT KEDIRI

NUR KHOLIS, Dr. Devi Oktaviana Latif, S.T., M.Eng.

2022 | Tugas Akhir | D4 TEKNOLOGI REKAYASA PELAKSANAAN BANGUNAN SIPIL

Dhoho International Airport merupakan Bandar Udara yang terletak di kaki gunung Wilis barat laut Kota Kediri. Landasan pacu Bandara memiliki lebar 45 m dan panjang 3360 m dengan luas 371 Ha. Pembangunan Dhoho International Airport terdiri dari pekerjaan Earthwork, Airside, dan Landside. Permasalahan yang terjadi pada pembangunan Bandara pada area Runway terutama di Settlement 6 BHB 6-03 dan BHB 6-06 adalah tanah didominasi oleh tanah lunak dengan kedalaman yang bervariasi dengan nilai N-SPT 9-15. Pemecahan permasalahan dilakukan dengan soil improvement di area runway. Pada kondisi tanah yang umumnya didominasi oleh pasir berlanau hingga lanau kelempungan. Sesuai dengan SNI Geoteknik 8460-2017, maka digunakan metode dynamic compaction, stone column, dan soil replacement. Kombinasi dari dynamic compaction, stone column, dan soil replacement disebut sebagai Downhole Deep Compaction (DDC). Metode ini umunya digunakan untuk menstabilkan tanah yang mudah tuntuh (loess). Tujuan dari penelitian ini adalah untuk mengetahui pola dan jarak yang paling efektif pada saat menggunakan metode perbaikan tanah Downhole Deep Compaction (DDC) di Settlement 6. Pola persegi DDC dipilih untuk perbaikan tanah di area Runway dengan kedalaman 9 m dan jarak center to center pile DDC adalah 3 m. Analisis desain DDC menggunakan metode manual dan metode Finite Element. Dimana masing-masing analisis manual dan Finite Element di BHB 6-03 dan BHB 6-06 didapatkan nilai Settlement 59.36 mm, 64.96 mm dan 75 mm, 87 mm. Nilai Settlement tersebut sudah masuk kriteria desain perencanaan yaitu nilai Settlement pada 10 tahun masa layan tidak boleh lebih dari 100 mm. Untuk nilai distribusi tegangan pada BHB 6-03 dan BHB-06 adalah 52.5 ton dan 58.2 ton, dimana nilai ini digunakan untuk Design Load DDC. Pengujian Pile DDC dilakukan menggunakan Static Loading Test (SLT) dengan nilai Design Load didapatkan dari nilai Distribusi Tegangan. Sesuai dengan persyaratan SNI Geoteknik 8460-2017 beban uji yang direkomendasikan adalah 200% dari Design Load. Hasil pengujian Pile DDC didapatkan nilai Settlement saat kondisi loading maksimum sebesar 33.5 mm dengan penurunan permanen pada tiang DDC setelah beban dilepas adalah sebesar 23.5 mm dengan beban 154 ton. Dilihat dari penurunan aksial yang terjadi relatif kecil maka tiang DDC ini memiliki kualitas yang cukup baik dan dipastikan dapat menahan beban rencana sesuai desain yaitu sebesar 58.2 dan 52.5 ton. Kata Kunci: Airport, Runway, Downhole Deep Compaction, Settlement, Soil Improvement, Drilling Log, Crushed Stone, Coarse Grained, Finite Element, Static Loading Test.

Dhoho International Airport is an airport located at the foot of Mount Wilis, northwest of Kediri City. The airport runway has a width of 45 m and a length of 3360 m with an area of 371 hectares. The construction of Dhoho International Airport consists of Earthwork, Airside, and Landside works. The problem that occurs in the construction of the airport in the Runway area, especially in Settlement 6 BHB 6-03 and BHB 6-06, is that the soil is dominated by soft soil with varying depths with N-SPT values 9-15. Problem solving is done by soil improvement in the runway area. In soil conditions which are generally dominated by silty sand to loamy silt. In accordance with SNI Geotechnical 8460-2017, the dynamic compaction, stone column, and soil replacement methods are used. The combination of dynamic compaction, stone column, and soil replacement is known as Downhole Deep Compaction (DDC). This method is generally used to stabilize loose soils. The purpose of this study was to determine the most effective pattern and distance when using the Downhole Deep Compaction (DDC) soil improvement method in Settlement 6. The DDC square pattern was chosen for soil improvement in the Runway area with a depth of 9 m and a center to center pile distance of DDC is 3 m. The DDC design analysis uses the manual method and the Finite Element method. Where each manual analysis and Finite Element in BHB 6-03 and BHB 6-06 obtained Settlement values of 59.36 mm, 64.96 mm and 75 mm, 87 mm. The Settlement value has entered the planning design criteria, namely the Settlement value at 10 years of service cannot be more than 100 mm. For the stress distribution values at BHB 6-03 and BHB-06 are 52.5 tons and 58.2 tons, where these values are used for Design Load DDC. Pile DDC testing is carried out using the Static Loading Test (SLT) with the Design Load value obtained from the Voltage Distribution value. In accordance with the requirements of SNI Geotechnical 8460-2017, the recommended test load is 200% of the Design Load. The results of the Pile DDC test showed that the settlement value when the maximum loading condition was 33.5 mm with a permanent decrease in the DDC pile after the load was removed was 23.5 mm with a load of 154 tons. Judging from the relatively small axial settlement, this DDC pile has a fairly good quality and is certain to be able to withstand the design load according to the design, namely 58.2 and 52.5 tons. Keywords: Airport, Runway, Downhole Deep Compaction, Settlement, Soil Improvement, Drilling Log, Crushed Stone, Coarse Grain, Finite Element, Static Loading Test.

Kata Kunci : Kata Kunci: Airport, Runway, Downhole Deep Compaction, Settlement, Soil Improvement, Drilling Log, Crushed Stone, Coarse Grained, Finite Element, Static Loading Test.