Manfaatkan dan tingkatkan mutu pendidikan demi kemajuan Indoensia, sebuah wawancara Gouw dengan majalah Konstruksi tahun 1997, lengkapnya bisa dibaca dengan klik link ini: konstruksi-253-mutu-pendidikan-utk-kemajuan-indonesia-1997a
Abstract: The use of hybrid Reinforced Soil Slopes combining anchored gabion units and high strength geogrids for infrastructures development is growing in Indonesia. Hybrid RSS are considered a valid and competitive alternative to other traditional earth retaining structures. Despite this growth, civil engineers and construction companies are not yet familiar with the related design and construction aspects. This paper intends to share the Author’s experience regarding the design and the construction of the first stage of a 25 m high hybrid RSS for the new touristic airport at Central Sulawesi, Indonesia. It is worth to note that the RSS was built on soft and weathered clay shales and cohesive backfilling materials were used as part of the reinforced soil mass. This paper aims to present the main technical issues related to the project, the design process, which was carried out using both FEM and Limit Equilibrium method software, and the relevant construction aspects.
Download for full paper: 161107-11-gtl-6th-arc-on-geosynthetics
Abstract: The use of planar polymeric and metallic reinforcements in mechanically stabilized earth structures has been growing in Indonesia in the last few years. This modern technique has been evaluated to be competitive if compared to other traditional earth retaining structures and has been safely employed in strategic infrastructure development projects in Indonesia. At the same time, there is still a lack of knowledge regarding the design methodologies for the mentioned structures among Civil Engineers. At present, there are two main currents followed by Engineers in order to design reinforced soil slopes and walls: Limit Equilibrium (LE) methods and Finite Element analysis. Several LE methods have been developed for slope stability analysis in the last decades, each is based on different assumptions and hypothesis and all of them utilize the well-known Mohr-Coulomb expression to determine the available shear strength along a potential sliding surface. The aim of this paper is to present the design basis of MSE walls/slopes using Janbu modified and Bishop modified Limit Equilibrium methods. The paper describes also how to include the presence of planar reinforcements in the LE formulations for the global stability and internal stability checks according to the so called “rigid model”. Moreover, the procedure to properly calculate the long-term tensile strength of the planar reinforcements to be used in the LE formula will be presented.
Download full paper: Paper 4_GEO_Indonesia_2016_Lelli_RS design with LE methods
Abstract: Having the origin from the sedimentation of volcanic materials, many experienced Indonesian geotechnical engineers have long suspected that Jakarta reddish and grayish clay may have different characteristics compared to other clayey soils known in many geotechnical text books. Despite of carefully derived design parameters, experiences in the execution of deep excavation, be it open cut slope or protected excavation by either contiguous bored pile or diaphragm walls, often show that the performance of the geotechnical structures were better than predicted by the available design geotechnical software. Although, some engineers have started using more advanced constitutive soil models, such as: Hyperbolic and Cam Clay models. Undoubtedly, many engineers still use the bilinear Mohr-Coulomb model in their analysis. So far, to the author knowledge, there is no published paper discussing about the suitability of the soil models for modelling Jakarta red clay, in particular. Therefore, the author tried to find out which soil constitutive models can better predict the behavior of the Jakarta reddish/grayish clay. Available models in PLAXIS software, e.g.; Mohr-Coulomb, Hardening (hyperbolic), and Soft Soil models, were tried by simulating isotropically consolidated undrained triaxial test and compared it with the actual test data. At this stage it was found that none of the model can correctly predict the stress strain curve neither the correct stress path.
Download Full Paper: GOUW-2014-1021-FindingSuitableModel
ABSTRACT: Instability and intolerable deformation always be the problems in constructing high embankment over soft/ loose soils. The prime cause of the problems is the load exerted by the self-weight of the embankment fill itself. Therefore, whenever possible, the use of lightweight materials, such as Expanded Polystyrene (EPS) foam, for the embankment fill will certainly be one of the best solution. This technique has been implemented in the Scandinavian countries. Seeing that it may also be implemented in our country, Indonesia, this paper tries to introduce the engineering characteristics of the EPS foam, as obtained from manufacturer, together with its design aspects.
Download Full Paper: GTL-001-1990_(R) Expanded Polystyrene for Road Embankment on Soft Clay
|ABSTRACT: The capacity of laterally loaded group piles are conventionally analyzed by simply reducing the lateral subgrade reaction of the soil, kh. The lateral subgrade reaction is reduced to 0.35 kh, when the piles center to center distance is at 3 pile diameter and linearly increases up to 1.0 kh when the piles center to center distance is equal or higher than 8 pile diameter. It seems there is no consideration to the thickness of the pile cap and magnitude of lateral movement of the piles on this conventional approach. By using 3D finite element geotechnical software, the effect of these two factors can now be investigated. This paper presents the study on the impact of those two factors on lateral capacity of group piles. The study reveals that when base friction of the pile cap and the passive pressure acting against the pile cap is neglected, the effects of the pile cap thickness against group lateral efficiency is marginal and can be safely neglected. The center to center pile spacing and the lateral movement of the piles do play important roles in the capacity of the laterally loaded piles. The greater the pile spacing the greater the lateral group efficiency, so does the lateral movement.|
link to download full paper: http://www.ejge.com/2015/Ppr2015.1320ma.pdf
Sejauh ini teknik perbaikan tanah yang terbanyak diaplikasikan di Indonesia adalah aplikasi vertikal drain untuk meningkatkan kuat geser undrained dan untuk mempercepat penurunan konsolidasi pada tanah lempung lunak. Terdapat banyak makalah-makalah akademis yang mengatakan bahwa efektifitas vertikal drain perlu diperhitungkan terhadap efek gangguan saat pemasangan (smear effect) dan efek hambatan alir (drain resistance). Makalah ini menganalisa dan membahas seberapa besar efek dua faktor tersebut dalam kasus nyata di dua proyek perbaikan tanah di Balikpapan dan Bontang, Kalimantan, Indonesia. Dari analisa data-data penurunan dan monitoring piezometer terlihat bahwa efek gangguan dan efek tahanan alir tersebut dapat dikatakan tidak berarti. Dengan kata lain dalam proyek dengan vertikal drain yang dipasang sedalam 12 dan 27m ini kedua efek tersebut dapat diabaikan.
Download full paper: GOUW-2015-1125-EfekGangguan-HambatanAlir-PVD
Abstract: The application of geosynthetics for reinforced earth, also known as mechanically stabilized earth, is gaining popularity in Indonesia. At the same time, many engineers have started using geotechnical finite element software in designing the geosynthetics reinforced earth. Unfortunately, many of them still do not know the importance of elongation factor in determination of the geosynthetics stiffness to be input into the finite element calculation. Some engineers even said that elongation of the geosynthetics need not be considered in selecting the right geosynthetics material, only the breaking strength and the type of geosynthetics need to be considered. Such misconception can lead to bad performance or even failure of the geosynthetics reinforced earth. This paper elaborates the importance of the elongation factor and the correct procedure in determining the stiffness of geosynthetics materials for finite element software input.
Keywords: Elongation, stiffness, geosynthetics, finite element analysis
Download full paper: Gouw-2015-0927-ElongationFactorinGeosynthetics-Proc-SLOPE 2015
Abstrak: Krisis ekonomi berkepanjangan semenjak akhir 1997 mengakibatkan banyak proyek yang terbengkalai cukup lama, diantaranya adalah galian basement yang ditinggalkan begitu saja. Makalah ini membahas salah satu proyek dengan galian basement yang sudah diselesaikan hingga kedalaman final antara 14-16.5m dari muka tanah asli. Sistem dinding penahan tanah yang digunakan adalah dinding diaphragma dengan tiga dan empat lapis angkur tanah. Saat krisis ekonomi melanda, kegiatan proyek dihentikan total, dewatering air tanah tidak lagi dilakukan, hanya pemompaan air permukaan saja yang dilakukan, itupun dengan intensitas yang sangat kurang. Galian dibiarkan terbuka selama lebih dari 6 tahun. Pertengahan Juni tahun 2003, dilakukan pengukuran-pengukuran, diantaranya: defleksi dinidng penahan tanah, gaya-gaya yang bekerja pada angkur tanah. Pengukuran ini diikuti dengan evaluasi terhadap kinerja angkur tanah dan keamanan dinding diaphragma. Diketahui bahwa angkur tanah mengalami kehilangan gaya-gaya yang cukup signifikan, yang bila dibiarkan akan dapat mempengaruhi keamanan dinding diaphragma. Disimpulkan bahwa diperlukan konstruksi berm untuk menambah kesatabilan dinding diaphragma sebagai tindakan preventif.
Download full paper: GTL-J03-2004-HATTI-Kinerja Jangka Panjang Angkur Tanah
A graduate student from Texas A&M University asked:
I’m currently working on a project related to Rail Embankments. How a repetitive/ cycling loading can be simulated in a typical FEM model (I’m using PLAXIS 2D) considering the effect of fatigue.
Use HS small soil model, cyclic loading can then be simulated by choosing dynamic analysis and the loading vs time can be created by making a text file first in Notepad (left column is time, right column is magnitude of loading).