J Prayogo^[1]*, F Faris², H C Hardiyatmo³

¹Master student in Natural Disaster Management Engineering, Department of Civil and Environmental Engineering Universitas Gadjah Mada, Yogyakarta, Indonesia

²Directorate General of Human Settlements, The Ministry of Public Works and Housing, South Jakarta, Indonesia

³Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada, Yogyakarta, Indonesia

^[1]* Corresponding author’s email: [email protected]

DOI: https://doi.org/10.20885/icsbe.vol4.art38

Abstract.

The Malalayang Beach area is a strategic tourist destination close to Manado city. Arrangement of the area is carried out by building several buildings that can support this area as a tourist destination. Liquefaction is a phenomenon when the soil loses its strength of contact between particles. This is due to earthquake shocks that trigger an increase of water pressure in areas with loose sand characteristics (not dense). The settlement of soil due to liquefaction is a vertical deformation of the soil in the soil layer caused by soil compaction due to earthquakes. The study purpose is to determine how much reduction could occur at the research site as an early stage of the early stages of risk management. With the N-SPT data, the Yoshimine method and the computational method Rocscience Settle 3D can be used to analyze the settlement. Yoshimine method indicates settlement with a very low classification in BH-MLY-01 and high in BH-MLY-05. In RS Settle 3D, the location of BH-MLY-01 has a very low classification, and the location of BH-MLY-05 is dominated by low classification. The maximum settlement resulted from the Rocscience Settle 3D at the BH-MLY-05 location by 11,588 cm.

Keywords: Liquefaction; The settlement of soil; Risk Management

REFERENCES

PT. SOILENS 2021 Laporan Penyelidikan Tanah untuk Proyek Kawasan Pantai Malalayang dan Penataan Ecotourism Village Bunaken Sulawesi Utara Indonesia, PT. SOILENS

Towhata I 2008 Geotechnical Earthquake Engineering. (1^st Edition), Springer Science & Business Media, Berlin

Hermansyah D 2018 SETTLEMENT (PENURUNAN) (Rangkaian dan pembahasan serta penjelasan tentang settlement). Yogyakarta

Whittaker D N and Reddish D J 1989 Subsidence Occurence, Prediction and Control, DME Univ of Notthingham, Elsiver, New York, p 359-376

Zhang G, Robertson P K and Brachman R W I 2002 Estimation Liquefaction Induced Ground Settlement from CPT for Level Ground. Canadian Geotechnical Journal, 39, pp.1168-11680.

Ishihara K and Yoshimine M 1992 Evaluation of settlements in sand deposits following liquefaction during earthquakes, Soils Found, 32(1), 173-188

Rocscience Inc Team 2022 Settle3 User Guide: Settlement and consolidation analysis Theory Manual, 2007-2022 Rocscience Inc

SNI 1726:2019 2019 Tata Cara Perencanaan Ketahanan Gempa untuk Struktur Bangunan Gedung dan Nongedung. Jakarta: Badan Standardisasi Indonesia.

Kanno T, Narita A, Morikawa N, Fujiwara H, and Fukushima Y 2006 A new attenuation relation for strong ground motion in Japan based on recorded data. Bulletin of the Seismological Society of America, 96(3), 879-897.

Idriss I M and Boulanger R W 2008 Soil Liquefaction during Earthquake. EERI Publication, Monograph MNO-12, Earthquake Engineering Research Institute, Oakland

Yoshimine M, Nishizaki H, Amano K, and Hosono Y 2006 Flow deformation of liquefied sand under constant shear load and its application to analysis of flow slide in infinite slope, Soil Dynamics and Earthquake Eng. 26, 253–264

Barlett S F, Gerber A P, and Hinckley D 2007 Probabilistic Liquefaction Potential and Liquefaction Induced Ground Failure Map for The Urban Wasatch Front. Collaborative Research. USA: Universitas of Utah and Bringham Young University

Kezia Ruus^1*, Ahmad Rifa’i¹, Agus Darmawan Adi¹

¹Universitas Gadjah Mada, Sleman, Indonesia, 55281

^1*Corresponding email: [email protected]

DOI: https://doi.org/10.20885/icsbe.vol4.art36

ABSTRACT

The Sidoarjo mud volcano is a geological disaster which still erupting after 16 years located in a densely populated. The eruption of Sidoarjo mud volcano is the longest continous disaster that Indonesia has ever experienced. It is known that there is overpressure in subsurface that propagated to the surface throught faults. However, the overpressure generation leads to the increase of pore water pressure, so the effective soil stress decreases. This study aims to estimate the change of pore water pressure and effective stress on the subgrade of Sidoarjo mud volcano due to the subsurface pressure. Furthermore, this study considers the existing embankment and excess pore water pressure due to the consolidation process using Finite Element Method. The results show high active pore water pressure in these area is around -580 kPa, due to the consolidation process is -372 kPa and the contribution of subsurface pressure is -208 kPa. The anomaly of effective stress occur from a depth of -13 m to -30 m. Thus, the reduction of effective stress is around 6%-56% from the ideal conditions with the largest reduction occurred at a depth of -30 m.

Keywords: subsurface pressure, pore water pressure, effective stress

REFERENCES

Mazzini A et al., 2007 Triggering and dynamic evolution of the LUSI mud volcano, Indonesia Earth Planet. Sci. Lett. 261, 3–4 p. 375–388.

Tingay M, 2010 Anatomy of the Lusi Mud Eruption, East Java ASEG Ext. Abstr. 2010, 1 p.1–6.

Davies R J Swarbrick R E Evans R J and Huuse M, 2007 Birth of a mud volcano: East Java, 29 May 2006 GSA Today 17, 2 p. 4–9.

Davies R J Brumm M Manga M Rubiandini R Swarbrick R and Tingay M, 2008 The East Java mud volcano (2006 to present): An earthquake or drilling trigger? Earth Planet. Sci. Lett. 272, 3–4 p. 627–638.

Tingay M, 2015 Abnormal pore pressure and associated environmental and geohazards Initial pore pressures under the Lusi mud volcano , Indonesia Interpret. Vol. 3, No. 1 (February 2015); p. SE33–SE49, 5 3, 1.

Tanikawa W Sakaguchi M Wibowo H T Shimamoto T and Tadai O, 2010 Fluid transport properties and estimation of overpressure at the Lusi mud volcano, East Java Basin Eng. Geol. 116, 1–2 p. 73–85.

Rempe M Di Toro G Mitchell T M Smith S A F Hirose T and Renner J, 2020 Influence of Effective Stress and Pore Fluid Pressure on Fault Strength and Slip Localization in Carbonate Slip Zones J. Geophys. Res. Solid Earth 125, 11.

Andreas H Abidin H Z and Kusuma M A, After Four Years of Ground Displacements Following LUSI Mud Volcano Eruption ; Sign of its Ending Eruption After Four Years of Ground Displacements Following LUSI Mud Volcano Eruption ; Sign of its Ending Eruption May 2011 p. 18–22.

Abidin H Z Davies R J Kusuma M A Andreas H and Deguchi T, 2009 Subsidence and uplift of Sidoarjo (East Java) due to the eruption of the Lusi mud volcano (2006-present) Environ. Geol. 57, 4 p. 833–844.

Chaussard E Amelung F Abidin H and Hong S H, 2013 Sinking cities in Indonesia: ALOS PALSAR detects rapid subsidence due to groundwater and gas extraction Remote Sens. Environ. 128 p. 150–161.

PPLS, 2021, Laporan Akhir Paket Pekerjaan Penilaian Kinerja Sarana dan Prasarana Pengendalian Lumpur (PT Aditya Engineering Consultant), Surabaya.

Handoko L Rifa’i A Yasufuku N and Ishikura R, 2015 Physical properties and mineral content of Sidoarjo mud volcano Procedia Eng. 125, December p. 324–330.

Agustawijaya D and Sukandi, 2012 The Stability Analysis of the Lusi Mud Volcano Embankment Dams using FEM with a Special Reference to the Dam Point P10.D Civ. Eng. Dimens. 14, 2 p. 100–109.

Sungkono Husein A Prasetyo H Bahri A S Monteiro Santos F A and Santosa B J, 2014 The VLF-EM imaging of potential collapse on the LUSI embankment J. Appl. Geophys. 109 p. 218–232.

Agustawijaya D and Sukandi, 2017 The Displacement Models of The Lusi Mud Volcano Embankment November 2013.

Hakim, Abdul., Gunawan A, 2020 Evaluation of Sidoarjo mud volcano embankment AIP Conf. Proc. 2251, August.

Verruijt A, 2001 Soil Mechanics, Open courseware Technical University Delft.

Hardiyatmo H C, 2012 Mekanika Tanah I Ke enam Yogyakarta: Gadjah Mada University Press.

Hardiyatmo H C, 2019 Mekanika Tanah II Sixth Yogyakarta: Gadjah Mada University Press.

Washington State Department of Transportation, 2022 Geotechnical Design Manual M46-03.08 October .

Climent G H, 2017 Pore Water Pressure Behaviour and Evolution in Clays and Its Influence in The Consolidation Process p. 86.

Handoko L Yasufuku N Ishikura R and Rifa’i A, 2016 Comparison of consolidation curves for remolded mud volcano of Sidoarjo, Indonesia Int. J. GEOMATE 10, 4 p. 1978–1982.

Fox P J, 2003, Chapter 19: Consolidation and Settlement Analysis, (CRC Press LLC), p. 1–15.

Brinkgreve R B J, 2007 Plaxis 2D.V8 Delft University of Technology&PLAXIS b.v. Yhe Netherlands.

PPLS, 2019, Laporan Review Design Supervisi Peningkatan Tanggul, Embung, Sistem Drainase dan Embung di Kawasan Lumpur Sidoarjo (PT Tri exnas Consultant & Management Engineering KSO PT Atlantik Bina Persada Konsultan Teknik dan Supervisi), Surabaya.

F K Dewi ^1,2*, W Wilopo ¹ and D A Rinaldi², I Azwartika²

¹Departement of Geological Engineering, Universitas Gadjah Mada, Indonesia

²Ministry of Public Works and Housing, Indonesia

^1*Corresponding author: [email protected]

DOI: https://doi.org/10.20885/icsbe.vol4.art34

ABSTRACT

Landslides are disasters that can cause damage to the environment and infrastructure and disrupt community activities, especially in mountainous and hilly areas. Identifying the geometry and some physical characteristics of the landslide material is essential to determining the appropriate mitigation method. This study used electrical resistivity tomography (ERT) to investigate landslides on the spillway slope of Ciawi Dam, West Java. The identification was carried out a 2-D resistivity data along seven profiles over the landslide area using a Dipole-dipole configuration. Borehole data also supported it. Electrical resistivity tomography analysis shows that the northern part of the landslide location is dominated by the water-saturated zone and weathered rocks in the southern part. Borehole data support that the rock at the landslide location consists of tuffaceous sandstone with tuffaceous clay inserts that are moderate to highly weathered. The resistivity data from the line recorded along the axis of the landslide also indicated the failure surface.

Keywords: landslides, electrical resistivity tomography, dry dam

REFERENCES

Geojali M R, Tjahjono B and Rustiadi E 2020 Pemodelan Spasial Bahaya Longsor Di Das Ciliwung Hulu, Kabupaten Bogor Komputasi J. Ilm. Ilmu Komput. dan Mat. 17 311–8

Pusat Vulkanologi dan Mitigasi Bencana Geologi 2022 Peta Prakiraan Wilayah Terjadinya Gerakan Tanah pada Bulan Agustus 2022, Provinsi Jawa Barat

Sauri S and Hizbaron D R 2007 Penilaian Tingkat Kerentanan Menggunakan Spatial Multi Criteria Evaluation di Sebagian Daerah Rawan Longsor, Kabupaten Bogor Pembagian Harta Waris Dalam Adat Tionghoa Di Kec. Ilir Timur I Kota Palembang 1 1–13

Ulfah Rahayu A M, Ardiansyah A N and Nuraeni N S 2019 Wilayah Kerawanan Longsor Di Kecamatan Pamijahan Kabupaten Bogor J. Geogr. Gea 19 1–8

Dewi I K and Abdi F 2017 Evaluasi Kerawanan Bencana Tanah Longsor Di Kawasan Permukiman Di Daerah Aliran Sungai ( Das ) Ciliwung Hulu J. Emasains J. Edukasi Mat. dan Sains 4 381–8

Ramdani D, Krensawati D K and Apriyanti D 2020 Analisis Dan Pembuatan Peta Daerah Potensi Longsor Di Kabupaten Bogor Tahun 2019 Menggunakan Metode Pembobotan Pada Sistem Informasi Geografis ( Analysis And Map Of The Potential Longsor Area At Bogor in 2019 Using Weighting Methods On Geographic Informat J. Tek. 21 12

Rahmat Dwi H 2021 Identifikasi & Zonasi Rawan Longsor Berdasarkan Karakteristik Geomorfologi di Kecamatan Cisarua Kabupaten Bogor

Drahor M G, Göktürkler G, Berge M A and Kurtulmuş T Ö 2006 Application of electrical resistivity tomography technique for investigation of landslides: A case from Turkey Environ. Geol. 50 147–55

Bichler A, Bobrowsky P, Best M, Douma M, Hunter J, Calvert T and Burns R 2004 Three-dimensional mapping of a landslide using a multi-geophysical approach: The Quesnel Forks landslide Landslides 1 29–40

Iqbal M and Budiman A 2013 Investigasi bidang gelincir pada lereng menggunakan metode geolistrik tahanan jenis 2D (Studi Kasus: Kelurahan Lumbung Bukit Kecamatan Pauh Padang) J. Fis. Unand 2 88–93

de Bari C, Lapenna V, Perrone A, Puglisi C and Sdao F 2011 Digital photogrammetric analysis and electrical resistivity tomography for investigating the Picerno landslide (Basilicata region, southern Italy) Geomorphology 133 34–46

Gawing E S, Suaedi and Manrulu R H 2022 Identifikasi Bidang Gelincir Longsor di Jalan Lingkar Barat Kota Palopo Menggunakan Metode Geolistrik Konfigurasi Dipole-Dipole J. APCP 2

Chaniago A and Afdal 2022 Identifikasi Bidang Gelincir Pemicu Longsor dengan Metode Geolistrik Resistivitas 2 Dimensi Daerah Wisata Bukit Chinangkiek , Kabupaten Solok , Sumatera Barat J. Fis. Unand 11 160–5

Sugito, Irayani Z and Jati I P 2010 Investigasi Bidang Gelincir Tanah Longsor Menggunakan Metode Geolistrik Tahanan Jenis Di Desa Kebarongan Kec. Kemranjen Kab. Banyumas Berk. Fis. 13 49–54

Yodya Indra Indah KSO 2021 Laporan Review Desain Supervisi Pelaksanaan Bendungan Ciawi Lanjutan (Bogor)

BBWS CIliwungCisadane 2021 Laporan Curah Hujan Kabupaten Bogor

Salma Hobbi, Papalexiou S M, Chandra Rupa Rajulapati, Nerantzaki S D, Markonis Y, Tang G and Clark M P 2022 Detailed investigation of discrepancies in K¨oppen-Geiger climate classification using seven global gridded products 128–121

Effendi A c., Kusnama and Hermanto B 1998 Peta Geologi Regional Lembar Bogor, Jawa

PT. Indra Karya 2015 Laporan Akhir Bendungan Ciawi Report 471

Poespowardoyo R S 1986 Peta Hidrogeologi Indonesia; Lembar Jakarta 1:250.000

Abipraya P B and Sacna P 2021 Pengukuran Geolistrik di Bendungan Ciawi-Cipayung, Bogor Jawa Bawat 31