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Jurnal Geoteknik
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Articles 8 Documents
Research on Earthquake Induced Liquefaction in Padang City and Yogyakarta Areas Muntohar, Agus Setyo
Jurnal Geoteknik Vol 9, No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

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Abstract

Awareness and research on earthquake resistant building design has been intensively carried out after the fatal earthquakes in Indonesia in recent decades. However, less attention has been given to the phenomena of liquefaction due to lack of ground motion information and records at the hazard areas. In this paper, seismic ground response after two deadly earthquakes shocked Java and Sumatera (Indonesia) in 2006 and 2009 was evaluated based on the CPT data. Based on back-calculation results, the possible ground accelerations were expected to be about 0.48g and 0.14g in those liquefied areas at Yogyakarta (Southern Java) and Padang (West Sumatera) respectively. Those accelerations are likely to make 50% of the thickness of sand layer liquefied and induced about 1% ground settlementKeywords : liquefaction, peak ground acceleration, silty sand, CPT
Suction-Monitored Direct Shear Test on Unsaturated Sand and Sand-Kaolin Clay Mixture Purwana, Yusep Muslih; Nikraz, Hamid
Jurnal Geoteknik Vol 9, No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

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Abstract

One of the common devices for unsaturated soil strength testing is suction-controlled direct shear. In this device, suction is adjusted by controlling water pressure and air pressure during the test. Suction was generated indirectly by adjusting the specimen’s water content to the desired value. During the test, suction was monitored using the attached tensiometer. Thus in this method, pore water and pore air pressure control is no longer required. The tests were carried out using sand and sand-kaolin clay mixtures in 95:5 and 90:10 proportions. The results indicates that shear strength with respect to matric suction exhibits a bilinear envelope with an initial value of fb is higher than the effective internal friction f¢. Despite the suction capacity of the tensiometer was relatively low, this device was effective for low air entry soils such as sand or sand with relatively small portion of fine grained material. Keywords: Sand-kaolin clay mixtures, suction-monitored direct shear test, unsaturated shear strength
Bio-Mediated Soil : A Sustainable Ground Improvement Technique Min Le, Lee
Jurnal Geoteknik Vol 9, No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

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Abstract

ABSTRACT:  Bio-mediated soil has recently emerged as a new and sustainable soil improvement technique. This paper presents the results of investigation on the performances of bio-mediated soil improvement on sand and a typical tropical residual soil (sandy silt). A species of Bacillus group, B. megaterium was used to trigger calcite precipitation. The treatments were performed at various soil densities (85%, 90% and 95% maximum density), and treatment conditions (untreated, treated with cementation reagents only, and treated with B. megaterium and cementation reagents). Results showed that the MICP treatment which was often attempted on sand was equally robust in tropically residual soil. The shear strength of MICP-treated residual soil was improved by 40 - 164% compared to its untreated counterpart. The saturated hydraulic conductivity of the MICP-treated residual soil was reduced by 54 - 74%.  The effectiveness of the bio cementation and bio clogging in residual soil was mainly governed by the particle-particle contacts, porosity and pore spaces between soil particles. Future research may focus on in-situ applications of bio-mediated soil improvement and its effectiveness in fine-grained soils. Keywords: bio-mediated soil improvement, microbially induced calcite precipitation, biocementation, bioclogging, residual soil
Pengaruh Siklus Basah – Kering terhadap Kekuatan Geser dan Ekspansivitas Campuran Kaolin – Montmorillonit - Pasir Hendrikus, Edwin Laurencis; Nawir, Hasbullah
Jurnal Geoteknik Vol 9, No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

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Abstract

Sebagian besar daerah Indonesia terdiri dari tanah lempung ekspansif. Tanah ekspansif sering menyebabkan permasalahan geoteknik karena perilakunya yang sensitif terhadap air. Penelitian ini ditujukan untuk mempelajari efek siklus basah-kering terhadap perilaku tanah lempung ekspansif yang distabilisasi pasir. Perilaku yang ditinjau adalah kekuatan geser dan potensi pengembangan. Tanah yang digunakan adalah tanah artifisial yang dibentuk dari bentonit, kaolin, dan pasir. Pasir yang digunakan adalah pasir bergradasi baik. Ada dua variasi yang dilakukan dalam penelitian ini, yakni variasi jumlah siklus basah-kering dan variasi kadar mineral lempung. Kadar pasir ditetapkan sebesar 20% terhadap massa kering tanah. Pembentukan tanah artifisial dilakukan pada kondisi kadar air optimum, kemudian siklus basah-kering dilakukan pada tanah artifisial sebelum diuji. Beberapa pengujian dilakukan pada sampel ini, meliputi pengujian terhadap batas plastisitas, berat jenis, parameter pemadatan, distribusi ukuran butir pasir, dan kandungan mineral tanah. Melalui pengujian diperoleh hasil bahwa penambahan pasir sebesar 20% pada tanah ekspansif tidak mencegah penurunan kekuatan geser tak teralir, namun mereduksi potensi pengembangan. Dapat disimpulkan bahwa penambahan pasir hanya efektif untuk mencegah pengembangan dibandingkan untuk meningkatkan kuat geser tanah lempung ekspansif akibat siklus berulang basah-kering. Kata kunci: tanah ekspansif, stabilisasi tanah, pasir, siklus basah-kering
Pengaruh Siklus Basah – Kering terhadap Kekuatan Geser dan Ekspansivitas Campuran Kaolin – Montmorillonit - Pasir Hendrikus, Edwin Laurencis; Nawir, Hasbullah
Jurnal Geoteknik Vol 9 No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Sebagian besar daerah Indonesia terdiri dari tanah lempung ekspansif. Tanah ekspansif sering menyebabkan permasalahan geoteknik karena perilakunya yang sensitif terhadap air. Penelitian ini ditujukan untuk mempelajari efek siklus basah-kering terhadap perilaku tanah lempung ekspansif yang distabilisasi pasir. Perilaku yang ditinjau adalah kekuatan geser dan potensi pengembangan. Tanah yang digunakan adalah tanah artifisial yang dibentuk dari bentonit, kaolin, dan pasir. Pasir yang digunakan adalah pasir bergradasi baik. Ada dua variasi yang dilakukan dalam penelitian ini, yakni variasi jumlah siklus basah-kering dan variasi kadar mineral lempung. Kadar pasir ditetapkan sebesar 20% terhadap massa kering tanah. Pembentukan tanah artifisial dilakukan pada kondisi kadar air optimum, kemudian siklus basah-kering dilakukan pada tanah artifisial sebelum diuji. Beberapa pengujian dilakukan pada sampel ini, meliputi pengujian terhadap batas plastisitas, berat jenis, parameter pemadatan, distribusi ukuran butir pasir, dan kandungan mineral tanah. Melalui pengujian diperoleh hasil bahwa penambahan pasir sebesar 20% pada tanah ekspansif tidak mencegah penurunan kekuatan geser tak teralir, namun mereduksi potensi pengembangan. Dapat disimpulkan bahwa penambahan pasir hanya efektif untuk mencegah pengembangan dibandingkan untuk meningkatkan kuat geser tanah lempung ekspansif akibat siklus berulang basah-kering. Kata kunci: tanah ekspansif, stabilisasi tanah, pasir, siklus basah-kering
Research on Earthquake Induced Liquefaction in Padang City and Yogyakarta Areas Muntohar, Agus Setyo
Jurnal Geoteknik Vol 9 No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Awareness and research on earthquake resistant building design has been intensively carried out after the fatal earthquakes in Indonesia in recent decades. However, less attention has been given to the phenomena of liquefaction due to lack of ground motion information and records at the hazard areas. In this paper, seismic ground response after two deadly earthquakes shocked Java and Sumatera (Indonesia) in 2006 and 2009 was evaluated based on the CPT data. Based on back-calculation results, the possible ground accelerations were expected to be about 0.48g and 0.14g in those liquefied areas at Yogyakarta (Southern Java) and Padang (West Sumatera) respectively. Those accelerations are likely to make 50% of the thickness of sand layer liquefied and induced about 1% ground settlementKeywords : liquefaction, peak ground acceleration, silty sand, CPT
Suction-Monitored Direct Shear Test on Unsaturated Sand and Sand-Kaolin Clay Mixture Purwana, Yusep Muslih; Nikraz, Hamid
Jurnal Geoteknik Vol 9 No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

One of the common devices for unsaturated soil strength testing is suction-controlled direct shear. In this device, suction is adjusted by controlling water pressure and air pressure during the test. Suction was generated indirectly by adjusting the specimen’s water content to the desired value. During the test, suction was monitored using the attached tensiometer. Thus in this method, pore water and pore air pressure control is no longer required. The tests were carried out using sand and sand-kaolin clay mixtures in 95:5 and 90:10 proportions. The results indicates that shear strength with respect to matric suction exhibits a bilinear envelope with an initial value of fb is higher than the effective internal friction f¢. Despite the suction capacity of the tensiometer was relatively low, this device was effective for low air entry soils such as sand or sand with relatively small portion of fine grained material. Keywords: Sand-kaolin clay mixtures, suction-monitored direct shear test, unsaturated shear strength
Bio-Mediated Soil : A Sustainable Ground Improvement Technique Min Le, Lee
Jurnal Geoteknik Vol 9 No 01 (2014)
Publisher : Himpunan Ahli Teknik Tanah Indonesia (HATTI)

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

ABSTRACT:  Bio-mediated soil has recently emerged as a new and sustainable soil improvement technique. This paper presents the results of investigation on the performances of bio-mediated soil improvement on sand and a typical tropical residual soil (sandy silt). A species of Bacillus group, B. megaterium was used to trigger calcite precipitation. The treatments were performed at various soil densities (85%, 90% and 95% maximum density), and treatment conditions (untreated, treated with cementation reagents only, and treated with B. megaterium and cementation reagents). Results showed that the MICP treatment which was often attempted on sand was equally robust in tropically residual soil. The shear strength of MICP-treated residual soil was improved by 40 - 164% compared to its untreated counterpart. The saturated hydraulic conductivity of the MICP-treated residual soil was reduced by 54 - 74%.  The effectiveness of the bio cementation and bio clogging in residual soil was mainly governed by the particle-particle contacts, porosity and pore spaces between soil particles. Future research may focus on in-situ applications of bio-mediated soil improvement and its effectiveness in fine-grained soils. Keywords: bio-mediated soil improvement, microbially induced calcite precipitation, biocementation, bioclogging, residual soil

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