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Evi Aprianti
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International Association of Lowland Technology In Collaboration with Hasanuddin University and Saga University Address Faculty of Engineering, Center of Technology Building, 1st Floor Jalan Poros Malino km. 6, Bontomarannu, Gowa Indonesia Postal Code: 91711
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Lowland Technology International
Published by International Association of Lowland Technology
ISSN : 13449656     EISSN : 21878870     DOI : https://doi.org/10.0001/ialt_lti
Core Subject : Engineering,
Civil Engineering, Building, Construction & Architecture Engineering Transportation
The Lowland Technology International Journal presents activity and research developments in Geotechnical Engineering, Water Resources Engineering, Structural Engineering, Transportation Engineering, Urban Planning, Coastal Engineering, Disaster Prevention and Mitigation Engineering.
Arjuna Subject : Teknik (semua kategori) - Teknik Sipil dan Struktur
Articles 7 Documents
 1 
Search results for , issue "Vol 17 No 3, Dec (2015)" : 7 Documents clear
Compressive strengths of water treatment sludge-fly ash geopolymer at various compression energies C. Suksiripattanapong; T. Srijumpa; S. Horpibulsuk; P. Sukmak; A. Arulrajah; Y.J. Du
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Abstract

Sludge-fly ash geopolymer is a green material, which does not require cement as a cementitious binder. Sludge and fly ash (FA) are both by-products from Bang Khen water treatment plants and Mae Moh power plants, respectively. A liquid alkaline activator, L is a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH). This article investigates the influence of compression energy (E) on the Unconfined Compressive Strength (UCS) of a novel sludge-fly ash geopolymer. The optimal liquid alkaline activator (L) content, sodium silicate solution to sodium hydroxide solution ratio (Na2SiO3/NaOH), heat temperature (T) and heat duration (D), providing the maximum UCS for each E is also investigated. Test results indicate that the optimal L/FA ratio decreases as E increases. The optimal L/FA ratios for E = 592.5, 1346.6 and 2693.3 kJ/m3 are 1.5, 1.4 and 1.3, respectively. The Na2SiO3/NaOH ratio of 80:20 is considered as optimal for all E tested. The UCS of sludge-FA geopolymer at all E values tested increases with an increase of heat duration until a heat duration of 72 hours, after which the UCS becomes almost constant. The heat temperature accelerates the geopolymerization reaction and therefore enhances the strength. However, overheating results in micro-cracks in the samples due to the loss of moisture. As such, the optimal temperature is controlled by liquid content; the higher L/FA results in the lower optimal heat temperature. Since the optimal L/FA ratio decreases as E increases, the optimal T subsequently decreases with an increase in E; i.e., its values are 75, 85 and 95 oC for E = 2693.3, 1346.6 and 592.5 kJ/m3, respectively. The maximum UCS values of sludge-FA geopolymer at optimal ingredient and heat condition are 20, 18 and 16 MPa for E = 2693.3, 1346.6 and 592.5 kJ/m3, respectively, which meet the strength requirement of bearing masonry units as specified by the Thailand Industrial Standard (TIS).
3D FEM investigation on bending failure mechanism of column inclusion under embankment load S. Shrestha; J.-C. Chai; D. T. Bergado; T. Hino; Y. Kamo
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Abstract

Bending failure mechanism of column inclusions in soft clay deposit under embankment loading has been investigated by three dimensional (3D) finite element analyses. Firstly the effectiveness of the numerical procedure has been verified by comparing the simulated and the measured results of a centrifuge model test reported in the literature in terms of lateral displacement, settlement, and the bending moment in the column. Then the effects of the size of the column improved area from the toe toward the center of the embankment, stiffness of the column, the length of the column on the maximum bending moment in the column have been investigated numerically. The numerical results indicate that increase the size of the improved area, reduced the bending moment in the upper part (near ground surface) of the column; increase the stiffness of the column increased the maximum bending moment; and the maximum bending moment occurred at the end of the column in the case of an end bearing column, and in the upper part of the column for a floating column. The numerical results also indicate that when the whole area under the embankment is improved by end bearing columns with an area improvement ratio of 28 % and tensile strength of the column of 100 kN/m2, the embankment load can be applied with a factor of safety of about 2 for bending failure of the columns is about 13 times of the initial undrained shear strength of the soft deposit.
The influence of soil disturbance on material properties and micro-structure of cement-tretaed soil M. Makino; T. Takeyama; M. Kitazume
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Abstract

The Pneumatic Flow Mixing Method was developed in Japan, in which dredged soft soil is mixed with small amount of chemical binder, usually cement, in a pipe during transporting by compressed air. In some applications, the stabilizied soil is temporary placed at provisional spaced, and is excavated and reclaimed at the final site due to several reasons. In the cases, the stabilized soil in which the chemical reaction has already proceeded is disturbed during the excavation and transportation processes, which causes considerable decrease in the strength at the final state. It is important to investigate the soil disturbance effect for its further applications. The authors have started a research project to investigate the soil disturbance effect on the mechanical properties of cement stabilized soil. The unconfined compression tests were perfomed on three types of laboratory mixed cement stabilized Kaolin clay, stabilized soil without disturbance and disturbed after 3 or 7 days curing. The study revealed that the soil disturbance influenced the stress – strain behavior of the soils considerably. In this paper, a part of the on-going research results is presented as well as the soil preparation and test procedure.
Using the memetic algorithm to determine the depths of sedimentary basins by 2-D gravity modeling L.P. Toan; D.V. Liet
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Abstract

In this article, the memetic algorithm using gravity data is applied to determine the thickness of a 2-D sedimentary basin whose density contrast varies with depth as a parabolic function. This memetic algorithm is a combination of the genetic algorithm and the Nelder-Mead Simplex local search to find optimal global solutions based on the minimum of the objective function, which is the total of data misfit  d and the ‘norm’ model  m and the second term is multiplied by the weight parameter namely a Tikhonov regularization. The program is written in Matlab. Firstly, it was tested on a synthetic model and the interpretable results are coincident with the model. Then, it was applied on An Giang and Dong Thap gravity anomalies in the Mekong Delta, Southwest of Vietnam, where the density contrast’s function of sediment layers was found from the density contrasts of each layer of CL-1 well’s stratigraphic column. The results showed that for both An Giang and Dong Thap anomalies, the observed and calculated gravity anomalies were fitted well, but the difference between the calculated depths using the memetic algorithm and the forward modeling method is slight because the approach to the solution of each method is different.
Anumerical model for transient temperature distribution in an aquifer thermal energy storage system with multiple wells S. Ganguly; M.S.M. Kumar
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Abstract

The present study is concerned about developing a coupled thermo-hydrogeological numerical model for an Aquifer Thermal Energy Storage (ATES) system consisting of a confined porous aquifer underlain and overlain by impermeable rock media with different thermo-hydrogeological properties. Hot water is injected through injection well(s) into the porous medium which is at subsurface temperature. The main motive of the study is to model the movement of the thermal-front which is generated in the aquifer due to hot water injection. First the numerical model is developed for an ATES system with single production well and multiple injection wells and then for a system with multiple production wells and a single injection well, as both the scenario occur in field. Influence of a few parameters involved in the subsurface heat transport process is determined. Parameters of injection rate, permeability of the aquifer and the confining rocks are proved to be very important. A simplified version of the model has been validated using an analytical model developed by the authors. Modeling the movement of the thermal-front is important in designing an injection-production well scheme to avoid thermal-breakthrough which severely affects efficiency of an ATES system.
Effect of trenches on the habitat of aquatic organisms in a salt marsh in Saga, Japan Y. Nagahama; K. Nishimura; H. Yamanishi
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Abstract

Trenches were constructed to control the growth of Phragmites australis on a riverbank in the Ushizu River in Saga, Japan. However, the effect of these trenches on the habitat of aquatic organisms is unclear. The purpose of this study is to clarify the effect that trenches have on aquatic organisms in the tidal river. The burrow density of a type of sand crab (Ilyoplax deschampsi) and the abundance of aquatic organisms (such as fish and shrimp) in our trenches were measured. The number of I. deschampsi burrows around trench D was similar to that observed before trench construction. However, mud sedimentation was accelerated in shallow trench D’, which created a suitable habitat for this species. Additionally, we found shrimp and gobies in all our trenches. This indicates that artificial trenches do provide habitat for shrimp and gobies in riverside marshes. Moreover, an endangered species and many aquatic insects were collected. Our results suggest that trenches provide important habitats for rare fishes and aquatic insects, similar to that of a lagoon.
Improvement strategy of open space at the center of a traditional lowland town with narrow paths for securing persons in need of aids viewing from evacuation time N. Mishima; Y. Taguchi; Y. Okazaki; H. Wakuya; K. Kitagawa; Y. Hayashida; Y.S. Oh; S.G. Park
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Abstract

This paper aims to discuss improvement strategy of an existing open space at the center of a traditional lowland town, in which local spatial heritage including narrow paths should be preserved. We calculated evacuation times not only of normal persons but also of persons in need of aids on the assumption of street blockades in narrow paths might occur by disaster such as large earthquake also with big fire. In the study area, we thought that the weedy vacant space at the center worked as an efficient evacuation route for residents. Yet, the calculation results showed that the evacuation time of person in need of hard aids was more than we expected in the case of street blockades, although the others could. It means that it is useful to maintain the vacant space at the center in the town in order to secure evacuation without damage of the traditional meanings of the area in lowland, but that the other measurements are also necessary especially for person in need of hard aids.

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