Evaluasi Perencanaan Pembangunan Shaft Untuk Microtunneling Proyek Jakarta Sewerage System (JSS) Zona 2

Syah Arrafi, Raditya Ahmad (2021) Evaluasi Perencanaan Pembangunan Shaft Untuk Microtunneling Proyek Jakarta Sewerage System (JSS) Zona 2. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pembangunan sistem pengolahan limbah diperlukan mengingat cakupan pengolahan limbah hanya 4% dari luas total yang ada di DKI Jakarta, maka diperlukan penambahan pipa untuk menyalurkan limbah menuju ke rumah IPAL (Induk Pengolahan Air Limbah). Braced excavation menjadi salah satu pilihan untuk melakukan pemasangan pipa yang terletak cukup dalam dan metode microtunneling dipilih untuk melakukan proses jacking pipa limbah. Pada pembagunan Jakarta Sewerage System di Jakarta Zona 2 merencanakan pembangunan pipa dengan metode galian braced excavation di beberapa titik.
Kedalaman galian pada struktur mencapai -15,0m, kedalaman galian bervariasi antara 8, 10, dan 15 meter menyesuaikan dengan lokasi pemasangan pipa. Metode galian yang dipilih yaitu metode braced excavation. Pekerjaan galian sangat rentan terhadap keruntuhan tanah, oleh karena itu dibutuhkan dinding penahan tanah yang berfungsi sebagai penahan tekanan lateral tanah. Konstruksi dinding penahan tanah yang dipilih pada proyek pembangunan ini yaitu Steel Sheet Pile dengan sistem penunjang wall to wall strut.
Persyaratan yang digunakan yaitu mengacu pada SNI 8460:2017, Taiwan Geotechnics Society (TGS):2001, Japan Society of Architecture:1988. Pemodelan dilakukan dengan metode elemen hingga program bantu PLAXIS. Dari pemodelan didapatkan hasil deformasi lateral dinding, gaya momen, gaya geser, safety factor, dan gaya aksial yang terjadi pada strut. Analisis dinding penahan tanah yangh dilakukan yaitu dengan push-in failure menghasilkan angka keamanan 1,5 dan analisis tanah dasar dengan basal heave menghasilkan angka keamanan 1,35 – 2,81. Analisis tersebut telah memenuhi persyaratan yaitu lebih dari 1,5. Perbandingan hasil analisa ulang kedalaman SSP menggunakan metode Rankine dengan metode padfield & Mair’s berbeda yaitu untuk shaft 001 didapatkan 28m dibandingkan dengan metode padfield & Mair’s didapatkan 18m. Adapun untuk analisa dewatering, untuk menurunkan muka air tanah sesuai yang direncanakan adalah 1 buah. Sedangkan kuat tekan strut berdasarkan perhitungan yang mengacu pada SNI 1727:2020 tentang Spesifikasi untuk Bangunan Gedung Baja Struktural yaitu berkisar 663 – 1253 kN, sehingga kekuatan strut pada beberapa galian memenuhi syarat. Kekuatan batang strut maksimum untuk potongan A-A adalah 1073 kN dan untuk kekuatan batang strut untuk potongan A-A Shaft 001 dan 003 sama-sama mampu menahan gaya aksial. Namun, terdapat 2 batang strut pada kedalaman -7,00 dan -8,5 pada Shaft 002 yang tidak memenuhi syarat tekan nominal. Hasil perhitungan jacking force berdasarkan metode Osumi didapatkan 485 ton, metode Chapman & Ichioda didapatkan 1911 ton, dan metode Bennet didapatkan 247.34 ton.
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The construction of a sewage treatment system is necessary considering that the coverage of waste treatment is only 4% of the total area in DKI Jakarta, so additional pipes are needed to channel waste to the IPAL (Wastewater Treatment Main) house. Braced excavation is one of the options for installing pipes that are located deep enough and the microtunneling method is chosen to carry out the process of jacking the waste pipe. During the construction of the Jakarta Sewerage System in Jakarta Zone 2, the pipeline is planned using the braced excavation method at several points.
The depth of excavation in the structure reaches -15.0m, the excavation depth varies between 8, 10, and 15 meters according to the location of the pipe installation. The excavation method chosen is the braced excavation method. Excavation work is very susceptible to soil collapse, therefore a retaining wall is needed that functions as a buffer against lateral soil pressure. The construction of the retaining wall chosen in this construction project is Steel Sheet Pile with a wall to wall strut support system.
The requirements used are referring to SNI 8460: 2017, Taiwan Geotechnics Society (TGS):2001, Japan Society of Architecture: 1988. The modeling was carried out using the finite element method of the PLAXIS program. From the modeling, the results obtained are lateral wall deformation, moment force, shear force, safety factor, and axial force that occurs in the strut. The analysis of retaining walls carried out by push-in failure resulted in a safety number of 1.5 and subgrade analysis using basal heave yielded a safety number of 1.35 – 2.81. The analysis has met the requirements of more than 1.5. The comparison of the results of the reanalysis of the depth of the SSP using the Rankine method with the Padfield & Mair's method is different, namely for shaft 001 it is 28m compared to the Padfield & Mair's method, it is 18m. As for the dewatering analysis, to reduce the ground water level as planned is 1 unit. Meanwhile, the compressive strength of the strut is based on calculations that refer to SNI 1727:2020 concerning Specifications for Structural Steel Buildings, which is in the range of 663 – 1253 kN, so that the strength of the struts in several excavations meets the requirements. The maximum strut strength for A-A pieces is 1073 kN and for strut bar strength for A-A pieces Shafts 001 and 003 are both able to withstand axial forces. However, there are 2 struts at a depth of -7.00 and -8.5 on Shaft 002 which do not meet the nominal compression requirements. The results of the calculation of the jacking force based on the Osumi method obtained 485 tons, the Chapman & Ichioda method obtained 1911 tons, and the Bennet method obtained 247.34 tons.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	Dinding penahan tanah, microtunneling, galian dalam, Dewatering, manhole, Retaining wall, microtunneling, deep excavation.
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA455.S6 Soil (Materials of engineering and construction) T Technology > TA Engineering (General). Civil engineering (General) > TA760+ Retaining walls
Divisions:	Faculty of Vocational > Civil Infrastructure Engineering (D4)
Depositing User:	Raditya Ahmad Syah Arrafi
Date Deposited:	30 Aug 2021 07:31
Last Modified:	30 Aug 2021 07:31
URI:	http://repository.its.ac.id/id/eprint/89563

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