Papers by Hasbullah Nawir
Applied Mechanics and Materials, 2015
An unconsolidated undrained (UU) test is one type of triaxial compression tests based on the natu... more An unconsolidated undrained (UU) test is one type of triaxial compression tests based on the nature of loading and drainage conditions. In order to imitate the UU triaxial compression tests, a UU triaxial emulator with a graphical user interface (GUI) was developed. It has 5 deformation sensors (4 radial deformations and one vertical deformation) and one axial pressure sensor. In addition, other inputs of the emulator are the cell pressure, the height of sample, and the diameter of sample, which are provided by the user. The emulator also facilitates the analysis and storage of measurement data. Deformation data fed to the emulator were obtained from real measurements [H. Nawir, Viscous effects on yielding characteristics of sand in triaxial compression, Dissertation, Civil Eng. Dept., The University of Tokyo, 2002]. Using the measurement data, the stress vs radial strain, stress vs vertical strain, and Mohr-Coulomb circle curves were obtained and displayed by the emulator.
Geotechnical, geological and earthquake engineering, 2022
SOILS AND FOUNDATIONS, 2004
Jurnal Teknologi
This research aims at investigating and modeling the axial bearing capacity degradation of a bore... more This research aims at investigating and modeling the axial bearing capacity degradation of a bored pile on clay shale due to the bored pile installation processes. Clay shale sample models were prepared to simulate the wetting and drying cycles through weathering process between 0 to 6 hours. All samples were tested in which every 1 hour of the weathering process representing 1 cycle of wetting and drying. The direct shear laboratory tests were performed to obtain the peak and residual shear strength parameters of the interface between the bored pile and clay shale. The peak and residual shear strength parameters were obtained after 6 hours of the weathering process. The residual shear strength parameters were measured by applying with and without stress release. This investigation showed that the shear strength degradation at peak, residual without stress release, and residual with stress release respectively reached 87-62%, 28-20%, and 25-14% after 1 to 6 hours of weathering proce...
Soils and Foundations, 2022
1 Ph.D candidate, Department of Civil Engineering, The University of Tokyo 2 Associate Professor,... more 1 Ph.D candidate, Department of Civil Engineering, The University of Tokyo 2 Associate Professor, Institute of Industrial Science, The University of Tokyo, Dr. Eng. 3 Associate Professor, Department of Civil Engineering, Bandung Institute of Technology Indonesia, Dr. Eng. 4 Post-doctoral researcher, Institute of Industrial Science, The University of Tokyo, Dr. Eng. 5 Graduate student, Department of Civil Engineering, The University of Tokyo 6 Technical Director, Institute of Industrial Science, The University of Tokyo
A system that consists of compression, imaging, and computation subsystems was successfully devel... more A system that consists of compression, imaging, and computation subsystems was successfully developed to determine Young’s moduli of clay samples. The compression subsystem utilized a Mark-10 instrument that has a compressor with a capacity of 11.3 Nm. The instrument also has a displacement sensor with a resolution of 0.01 mm and an integrated display that was used as a standard to compare deformations obtained from images. The imaging subsystem operated a Canon IVX digital camera to obtain images with sizes of 3000×4000 pixels. The computation subsystem exploited a personal computer (PC) installed with Scilab ver. 5.3.3 to process the images. Experimentally, a clay sample was initially prepared in cylindrical shape. The sample was then continuously compressed at the rate of 80 mm/min and its image was subsequently captured every second. Next, the obtained images were processed to extract deformation experienced by the sample. Finally, the sample deformation was used to calculate it...
Soils and Foundations, 2020
On 28th September 2018, an earthquake of Mw 7.5 struck Donggala Regency, Central Sulawesi, Indone... more On 28th September 2018, an earthquake of Mw 7.5 struck Donggala Regency, Central Sulawesi, Indonesia, resulting in a catastrophic disaster and a large numbers of casualties. In this report, the results of the preliminary field investigations carried out by the authors' team are summarized. The earthquake caused four major long-distance flow-slides on very gentle slopes of approximately 1-5% in and around Palu City: Balaroa, Petobo, Jono Oge and Sibalaya. The maximum flow distance at each site was several hundred meters or more. Spring waters were found in all affected areas even though there had not been a lot of rainfall before the survey. Interviews with local residents and witnesses of the flow-slide provided much evidence that the shallow groundwater in the affected areas had been pressurized before the earthquake. This confined groundwater is thought to have played an important role in the occurrence of longdistance flow-slide. In addition, the thickness of the flowed ground was found to be about 1.5 m by pit excavation survey in Jono Oge. Based on the results of the field survey and provided evidence, the likely fundamental mechanisms of the flow-slide are discussed.
Journal of Engineering and Technological Sciences, 2018
This paper presents the development of a method using local deformation transducers (LDTs) to loc... more This paper presents the development of a method using local deformation transducers (LDTs) to locally and sensitively measure small axial and lateral strains in soil in a compression test. A local strain measurement system comprising of axial and lateral LDTs was developed referring to the original LDT system and the cantilever LDT system, respectively. The LDTs were calibrated both in air and under water. Their insensitivity to pressurized water was confirmed. The calibration factors for the axial and lateral LDTs were found to be 1.695 mm/volt and 1.001 mm/volt, respectively. The performance in terms of repeatability and stability of the LDT system was evaluated. The repeatability test showed that the average standard deviation of the lateral LDT was 0.015 volt, while the stability test showed that the average standard error of the axial and lateral LDT were 3.13 × 10-5 volt and 2.65 × 10-5 volt, respectively. Unconfined compression tests were conducted on three reconstituted clay samples to examine the proposed axial and lateral LDT system. The stress-strain relationship indicates a nonlinear relationship between the axial and lateral strain of soil instead of the conventionally assumed constant relationship. The results demonstrate this nonlinear behavior even at small strain levels, which were successfully measured using a domestically built axial and lateral LDT system.
IPTEK Journal of Proceedings Series, 2017
paper presents numerical analyses of an excavation using stress path dependent soil parameters, w... more paper presents numerical analyses of an excavation using stress path dependent soil parameters, where soil elements in a region of the excavation are represented by specific soil parameters that correspond to their specific stress paths. The performance of the M1 excavation pit in Berlin sand was selected as the analysed case. This excavation pit was supported by diaphragm-wall with a single row of pre-stressed anchors. The numerical analyses of the excavation were performed using finite element program PLAXIS 3D. Mohr-Coulomb model and Hardening Soil model were used as the soil constitutive models. The analyses were performed using two approaches, which are: (i) analysis using axial compression soil parameters, and (ii) analysis using stress path dependent soil parameters. A set of conversion ratios were employed to convert the general soil parameters (i.e. axial compression stress path) to the soil parameters of the other stress paths. These conversion ratios were obtained from an experimental program of true triaxial tests conducted on Bangka sand. The comparison of the field records and the analysis results were discussed. The results show that the stress path dependent approach produced better prediction of diaphragm-wall deformation compare to the general approach using axial compression soil parameters.
Journal of Engineering and Technological Sciences, 2020
The Mw 7.5 Sulawesi Earthquake 2018 was a catastrophic disaster that resulted in large numbers of... more The Mw 7.5 Sulawesi Earthquake 2018 was a catastrophic disaster that resulted in large numbers of casualties. This study aimed to investigate the damages of liquefaction-induced-flow failure in three areas in Palu city, i.e. Petobo, Balaroa, and Jono Oge. It was found that this flow failure occurred on a large scale at a very gentle ground inclination, ranging from 1 to 3%. In order to gain an understanding of the soil conditions in these specific locations, Portable Dynamic Cone Penetration Tests were conducted in Petobo. The results showed that the soil layers in the affected area were in a loose state compared to the non-affected areas. Furthermore, some spots of freshwater inundation were recognized in Petobo and Balaroa, even two weeks after the disaster. Based on this evidence, a mechanism of liquefaction-induced-flow failure caused by a confined aquifer is proposed.
Jurnal Teknik Sipil, 2012
Penurunan konsolidasi tanah merupakan masalah geoteknik yang sering ditemukan pada kasus timbunan... more Penurunan konsolidasi tanah merupakan masalah geoteknik yang sering ditemukan pada kasus timbunan, terutama pada tanah lunak. Penurunan konsolidasi disebabkan oleh keluarnya air pori dari dalam tanah yang disebabkan oleh peningkatan tegangan pada massa tanah. Untuk memprediksi besar penurunan serta lama waktu konsolidasi umumnya digunakan teori konsolidasi satu dimensi Terzaghi. Prediksi penurunan konsolidasi dengan teori ini, pada banyak kasus, memberikan hasil yang lebih besar dari penurunan aktual. Hal ini, salah satunya, disebabkan adanya pengabaian fenomena perkuatan tanah yang mungkin terjadi akibat proses penimbunan secara bertahap. Selain teori tersebut terdapat pula prediksi penurunan tanah dengan metode elemen hingga yang sudah menganalisis penurunan secara dua dimensi bahkan tiga dimensi. Namun untuk metode ini prediksi penurunan terhadap waktu, terutama untuk kasus perbaikan tanah dengan drainase vertikal, metode ini tidak memberikan hasil yang baik. Observasi Asaoka. Melalui prosedur ini, besarnya penurunan akhir dapat diprediksi dengan menggunakan data observasi penurunan akibat timbunan dengan menggunakan metoda curve fitting. Studi ini juga membahas perbandingan metode perhitungan penurunan dengan menggunakan teori konsolidasi Terzaghi, metode elemen hingga dan metode observasi Asaoka.
Jurnal Geoteknik, 2014
Sebagian besar daerah Indonesia terdiri dari tanah lempung ekspansif. Tanah ekspansif sering meny... more 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
Tanah, sesuai dengan karakteristiknya, memiliki masalah masing-masing. Pada tanah jenis lempung, ... more Tanah, sesuai dengan karakteristiknya, memiliki masalah masing-masing. Pada tanah jenis lempung, daya dukung dalam memikul beban serta penurunan, baik dari segi besar penurunan maupun lama waktu konsolidasi, merupakan dua hal yang paling perlu diperhatikan pada suatu perancangan detail suatu infrastruktur. Sedangkan pada tanah yang tidak memiliki kohesi seperti pasir, likuifaksi merupakan potensi masalah yang akan menimbulkan kerusakan dan kemampuan layan dari suatu infrastruktur. Runway dan taxiway merupakan bagian terpenting dari suatu bandara. Kedua elemen ini memerlukan perencanaan yang sangat matang baik dari segi kekuatan maupun kemampuan layan, termasuk dari segi geoteknik.Untuk lapisan tanah lempung, daya dukung merupakan satu hal yang perlu dianalisis dengan cermat. Jika besar beban yang akan bekerja pada tanah dasar melebihi kapasitas daya dukung tanah pondasi, maka perlu dilakukan pembebanan awal (pre-loading) dengan proses konstruksi yang dilakukan secara bertahap. Tiap tahap pembebanan baru dapat dilakukan setelah tanah dasar terkonsolidasi akibat pembebanan sebelumnya sehingga tanah mengalami peningkatan kuat geser (gain strength) untuk mampu menahan beban pada tahapan konstruksi selanjutnya. Pada kondisi alami, tanpa perlakuan khusus pada tanah, waktu konsolidasi yang dibutuhkan sangat lama sehingga akan memperlambat proses konstruksi. Untuk mempercepat proses tersebut, diperlukan suatu perlakuan untuk mempercepat terjadinya konsolidasi, salah satunya adalah dengan memberi Prefabricated Vertical Drain (PVD).Lain halnya dengan tanah lempung, tanah pasir cenderung memiliki daya dukung yang besar dalam memikul beban dan tidak mengalami konsolidasi. Namun tanah pasir memiliki potensi masalah lain yang juga perlu diperhatikan, salah satunya adalah likuifaksi. Likuifaksi yang dipengaruhi oleh muka air tanah, distribusi ukuran partikel serta besar tegangan yang bekerja pada tanah dapat dianalisis dengan berbagai metode. Salah satu metode yang cukup sederhana namun telah mencakup semua faktor yang dapat menyebabkan likuifaksi seperti faktor muka air tanah, gempa dan tegangan serta ketahanan tanah, adalah metode Simplified Procedure yang diperkenalkan oleh Seed dan Idriss (1971).Pada Tugas Akhir ini, dilakukan analisis daya dukung, konsolidasi dan potensi likuifaksi pada sektor runway dan taxiway pada bandara internasional di Sumatera Utara. Hasil yang diperoleh menunjukkan bahwa dengan beban rencana yang akan dipikul, diperlukan empat tahapan penimbunan setinggi 1,0-2,0 meter tiap tahap tergantung kuat geser tanah pada saat penimbunan. Dari analisis konsolidasi, diketahui bahwa konfigurasi paling efektif dari Prefabricated Vertical Drain, yang merupakan solusi percepatan konsolidasi yang dipilih dalam Tugas Akhir ini, adalah konfigurasi segitiga dengan spasi 1,6 meter. Konfigurasi ini dapat mengurangi waktu konsolidasi secara signifikan yaitu dari 6,5 tahun menjadi 1 tahun. Pada analisis potensi likuifaksi, diperoleh hasil bahwa di sepanjang daerah kajian, terdapat potensi likuifaksi pada kedalaman 2,0 hingga 20,0 meter. Untuk meminimalisir dampak dari permasalahan ini, PVD dapat dipilih untuk mempermudah terjadinya aliran air pada saat gempa, selain pemadatan dan perbaikan desain struktural.
Telah dianalisis stabilitas Bendungan way Biha berlokasi di Sungai Way Biha, Lampung. Studi stabi... more Telah dianalisis stabilitas Bendungan way Biha berlokasi di Sungai Way Biha, Lampung. Studi stabilitas ini menganalisis desain perkuatan bendungan awal yang mengalami kerusakan akibat boiling sehingga terjadi penggerusan pada bagian bawah dari bendungan yang mengakibatkan bendungan tidak mampu menerima debit maksimum. Dengan melakukan analisis terhadap penyebab kerusakan dari bendungan penulis fmemberikan beberapa alternatif desain yang dapat membantu dalam pembangunan bendungan yang baru. Dari alternatif tersebut dianalisis mengenai stabilitas dari bendungan berdasarkan SF (safety factor) yang diminta owner. SF yang dimaksud ada 2 macam yaitu SF berdasarkan boiling dan uplift. Analisis berdasarkan boiling dan uplift ini dilakukan dengan menggunakan program seep/w. Dalam program ini dianalisis mengenai besarnya aliran air yang terajadi di bawah bendungan yang mengakibatkan terjadinya penggerusan pada bendungan dan menganalisis jenis-jenis dari lapisan tanah serta besarnya debit maksimum yang dapat diterima bendungan
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Papers by Hasbullah Nawir