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All Journal IPTEK Journal of Proceedings Series Journal of Engineering and Technological Sciences Jurnal Teknik Sipil
Dayu Apoji
Soil Mechanics Laboratory, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung,
Civil Engineering, Building, Construction & Architecture Computer Science & IT Engineering

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Excavation Analysis using Stress Path Dependent Soil Parameters Nawir, Hasbullah; Prasetyo, Bagus Eko; Apoji, Dayu
IPTEK Journal of Proceedings Series No 6 (2017): The 3rd International Conference on Civil Engineering Research (ICCER) 2017
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2017i6.3241

Abstract

This paper presents numerical analyses of an excavation using stress path dependent soil parameters, where soil elements in a region of an 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.
Axial and Lateral Small Strain Measurement of Soils in Compression Test using Local Deformation Transducer Hasbullah Nawir; Dayu Apoji; Riska Ekawita; Khairurrijal Khairurrijal
Journal of Engineering and Technological Sciences Vol. 50 No. 1 (2018)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2018.50.1.4

Abstract

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.
Prediksi Penurunan Tanah Menggunakan Prosedur Observasi Asaoka Studi Kasus: Timbunan di Bontang, Kalimantan Timur Hasbullah Nawir; Dayu Apoji; Rahmatyar Fatimatuzahro; M. Dwi Pamudji
Jurnal Teknik Sipil Vol 19 No 2 (2012)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2012.19.2.5

Abstract

Abstrak. 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.Abstract. Consolidation settlement is a general geotechnical problem found embankment, particularly those founded on soft soil. Consolidation settlement is caused by the discharge of soil pore water induced by the increas of stress in soil mass. Terzaghi one dimensional theory was used to predict the settlement and time rate of consolidation. In many cases, the settlement prediction from this theory provides results much greater than the observed value due to many factors including the neglection of soil strength gain that may occur during consolidation process. In addition, there is also settlement prediction by using observed settlement data from the site using curve fitting method. This study presents settlement prediction method using Terzaghi consolidation theory, finite element method and Asaoka observational method.
Settlement of a Full Scale Trial Embankment on Peat in Kalimantan: Field Measurements and Finite Element Simulations Endra Susila; Dayu Apoji
Jurnal Teknik Sipil Vol 19 No 3 (2012)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2012.19.3.6

Abstract

Abstract. This paper presents a study result of peat behaviors through numerical analysis using the finite element method verified by full scale field measurements. Site investigation, construction, instrumentation and monitoring of a trial embankment on very compressible fibrous tropical peat layers at Bereng Bengkel in Central Kalimantan have been conducted by the Agency of Research and Development, the Indonesia Ministry of Public Works. Settlement responses of the embankment have been investigated by a series of finite element simulations using two different soil constitutive models: elastic perfectly plastic model with the Mohr-Coulomb criteria and hyperbolic Hardening-Soil model. A half space finite element model has been developed using the effective stress approach. Analyses were performed with the coupled static/consolidation theory. The soil parameters, embankment geometry, construction sequence and consolidation time of peats and clays were modeled in accordance with actual field trial embankment conditions. Implementation of the numerical model and simulations has completely been performed by a computer program, PLAXIS 2D. For ground settlement behavior at center of embankment, this study result shows that both soil constitutive models have reasonably produced suitable deformation behaviors. However, the settlement behaviors at embankment toes are not as accurate as they are at center. Abstrak. Makalah ini menyajikan studi perilaku gambut melalui analisis numerik berdasarkan metode elemen hingga yang diverifikasi dengan pengukuran lapangan skala penuh. Investigasi lokasi, konstruksi, instrumentasi dan pengukuran timbunan di atas lapisan gambut tropis berserat yang sangat kompresibel di Bereng Bengkel, Kalimantan Tengah, telah dilakukan oleh Departemen Penelitian dan Pengembangan dari Departemen Pekerjaan Umum Indonesia. Respon penurunan timbinan ini telah dianalisis melalui serangkaian simulasi numerik elemen hingga menggunakan dua model konstitutif tanah: model elastis plastis sempurna dengan kriteria keruntuhan Mohr-Coulomb dan model hiperbolik Hardening-Soil. Model elemen hingga setengah ruang telah dibuat dengan pendekatan tegangan efektif. Seluruh tahapan simulasi telah diperhitungkan sebagai analisis statis/konsolidasi couple. Parameter tanah, geometri timbunan, tahapan konstruksi dan waktu konsolidasi gambut dan lempung dimodelkan sesuai dengan kondisi lapangan. Implementasi dari model dan simulasi numerik ini telah dilakukan menggunakan program komputer PLAXIS 2D. Untuk perilaku penurunan tanah di tengah timbunan, studi ini menunjukkan bahwa kedua model konstitutif tanah dapat menghasilkan perilaku deformasi yang cukup sesuai. Namun, prediksi perilaku penurunan tanah di kaki timbunan tidak seakurat prediksi perilaku di tengah timbunan.
Co-Authors Endra Susila Hasbullah Nawir, Hasbullah Khairurrijal Khairurrijal M. Dwi Pamudji Prasetyo, Bagus Eko Rahmatyar Fatimatuzahro Riska Ekawita