Metode 3D Tomografi Resistivitas Time-Lapse untuk Monitoring Pola Rembesan Air pada Tanggul Lumpur Sidoarjo (LUSI) P67 – P75

Sihombing, Hilda Liliana (2021) Metode 3D Tomografi Resistivitas Time-Lapse untuk Monitoring Pola Rembesan Air pada Tanggul Lumpur Sidoarjo (LUSI) P67 – P75. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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03411740000014-Undergraduate_Thesis.pdf - Accepted Version
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Abstract

Semburan lumpur di Sidoarjo yang terjadi mulai tahun 2006 masih terus berlangsung hingga sekarang. Tanggul LUSI berfungsi untuk menahan volume semburan lumpur yang terus menerus keluar, sehingga sangat penting untuk dilakukan monitoring yang bertujuan melihat apakah ada rembesan pada tanggul atau tidak. Pada titik P.67 – P.75 daerah penelitian membuktikan bahwa diperlukannya monitoring dikarenakan adanya 3 rembesan utama yang muncul di permukaan outer levee tanggul. Pada penelitian ini, monitoring tanggul dilakukan dengan metode Time Lapse Resistivity yang dimana digunakan untuk melihat perubahan nilai resistivitas batuan selama periode waktu yang sudah ditentukan. Metode resistivitas merupakan metode yang akan memodelkan keadaan bawah tanggul yang rentan terhadap rembesan air. Dalam penelitian ini, pengambilan data resisitivitas dilakukan pada dua periode yaitu, 21-22 Januari 2020 dan 11-12 Agustus 2020. Total lintasan pengukuran ada 4 lintasan dengan masing-masing panjang lintasan 90 meter. Data kemudian diolah menggunakan Voxler dengan metode gridding sehingga menghasilkan penampang 3D resistivitas. Hasil dari penelitian ini menunjukkan aliran rembesan pada lintasan 1 sampai 3 didominasi mengalir dari inner levee yang kemudian berlanjut ke arah Utara menuju lintasan 4 melalui pori bantuan. Peningkatan intensitas air juga terjadi pada periode 1 bertepatan dengan musim hujan, yang menunjukkan dipengaruhi oleh tinggi muka air pada tiap musim. Penyebab rembesan ini diperkirakan karena adanya penurunan tanah di daerah tanggul yang dimana didominasi oleh tanah yang lemah, yaitu tanah lempung. Hasil ini divalidasi dengan data bor dan data CPT yang memperoleh adanya kehadiran tanah ekspansif pada kedalmaan 18 – 30 meter, yang diduga sebagai penyebab terjadinya pengurangan padatnya tanah di bawah permukaan tanggul. ===================================================================================================== The mudflow in Sidoarjo that started in 2006 is still ongoing until now. The LUSI embankment functions to hold the volume of mudflow that continuously comes out, so it is very important to carry out monitoring aimed at seeing whether there is seepage on the embankment or not. At points P.67 – P.75 the research area proves that monitoring is needed because there are 3 main seeps that appear on the surface of the outer levee of the embankment. In this study, the embankment monitoring is carried out using the Time Lapse Resistivity method which is used to see changes in rock resistivity values over a predetermined period of time. The resistivity method is a method that will model the condition of the bottom of the embankment that is susceptible to water seepage. In this study, resistivity data has collected in two periods, namely, January 21-22, 2020 and August 11-12, 2020. The total measurement path are 4 tracks with each track length of 90 meters. The data have processed using Voxler with the gridding method so as to produce a 3D resistivity cross-section. The results of this study has indicated that the seepage flow on line 1 to 3 are dominated by flowing from the inner levee which then continues to the north towards line 4 through the rock pores. The increase in water intensity also occurred in period 1 coincided with the rainy season, which has indicated that it was influenced by the water level in each season. The cause of this seepage is thought to be due to land subsidence in the embankment area which is dominated by weak soil, namely clay. These results have validated with drill data and CPT data which found the presence of expansive soil at a depth of 18 – 30 meters, which has suspected to be the cause of the reduction in soil density below the surface of the embankment.

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: 3D, LUSI, resistivitas, tanggul, time-lapse, embankment, resistivity
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA749 Soil stabilization
T Technology > TC Hydraulic engineering. Ocean engineering > TC167 Dams, reservoirs
T Technology > TN Mining engineering. Metallurgy > TN269 Prospecting--Geophysical methods
Divisions: Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User: Hilda Liliana Sihombing
Date Deposited: 27 Aug 2021 08:49
Last Modified: 27 Aug 2021 08:49
URI: https://repository.its.ac.id/id/eprint/90184

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