Articles
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CAPACITY DESIGN CRITERIA FOR SEISMIC RESISTANCE OF PRECAST CONCRETE COLUMNS USING STEEL BOX CONNECTION
- Article Type: Research Article
- View Abstract
- Pages (1-9)
- No of Download = 617
Abstract
A variety of advantages of precast concrete adding to benefits of concrete has made the pre-fabrication and assembly systems widely adopted in building construction business. However, the connections may diminish the increase in the utilization due to their complication in the installation work and seismic design consideration. This paper presents an easy-to-install steel box for column base connection designed based on the standard capacity design criteria. Experimental investigations on the precast concrete columns using the steel box connection at the column base under cyclic loading were also made. The test results show the satisfactory seismic performance of the precast specimens both in seismic shear capacity, ductility and energy dissipation compared with the identical cast-in-place specimen. The failure of the precast columns, with proper details, was in the flexural ductile mode. The shear capacity was respectively 1.16-1.24 times higher than the averaged capacity of the cast-in-place column. The damping ratio was about 18-25 percent in the inelastic range, after the drift ratio of 3.0%. Finally, the seismic performance of the designed precast concrete column using the steel box connection based on the capacity design criteria is guaranteed without early brittle failures.
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ROBUST POSITIONING OF DRONES FOR LAND USE MONITORING IN STRONG TERRAIN RELIEF USING VISION-BASED NAVIGATION
- Article Type: Research Article
- View Abstract
- Pages (10-15)
- No of Download = 572
Abstract
For land use monitoring, the main problems are robust positioning in urban canyons and strong terrain reliefs with the use of GPS system only. Indeed, satellite signal reflection and shielding in urban canyons and strong terrain relief results in problems with correct positioning. Using GNSS-RTK does not solve the problem completely because in some complex situations the whole satellite's system works incorrectly. We transform the weakness (urban canyons and strong terrain relief) to an advantage. It is a vision-based navigation using a map of the terrain relief. We investigate and demonstrate the effectiveness of this technology in Chinese region Xiaoshan. The accuracy of the vision-based navigation system corresponds to the expected for these conditions. It was concluded that the maximum position error based on vision-based navigation is 20m and the maximum angle Euler error based on vision-based navigation is 0.83 degree. In case of camera movement, the maximum position error based on vision-based navigation is 30m and the maximum Euler angle error based on vision-based navigation is 2.2 degrees.
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DEEP FOUNDATION REFERENCE FOR METRO MANILA, PHILIPPINES
- Article Type: Research Article
- View Abstract
- Pages (16-21)
- No of Download = 887
Abstract
The study focuses on the analysis of the pile capacity and pile length for various cities of Metro Manila. Standard Penetration Test (SPT) N-values from soil reports were used to compute for the geotechnical parameters such as the undrained shear strength and the angle of internal friction which were directly applied in the computation of the allowable pile capacity. The estimation of the pile length, on the other hand, was done by means of determining the depth of the refusal or rock layer. The proposed minimum pile length and the allowable pile capacity values for each city are plotted to establish a contour map. By means of the collected borehole data, the allowable pile capacity was computed, which was shown in the reference as a series of contour maps. The contour maps were provided to show an overview of the soil’s pile capacity at various locations in Metro Manila, Philippines. The contour maps presented vary by means of the design of pile, the size of the pile and the proposed pile length for a specific city or municipality and for the entire Metro Manila. A Geographic Information System (GIS) database was made so as to have storage for the collected borehole data and their locations. The database can be updated for the availability of new data.
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PENETRATION BEHAVIOR OF CHEMICAL GROUTING CONSIDERING GROUND UNCERTAINTY
- Article Type: Research Article
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- Pages (22-27)
- No of Download = 547
Abstract
The chemical grouting is one type of ground-improvement methods. It injects liquid consolidation material into the gaps of a soft sandy ground. It is mainly used for improving a stable ground, such as by preventing liquefaction and increasing the strength of the ground. Chemical grouting has been successfully applied at many construction sites; however, the behavior of the chemical solution being injected into the ground is unclear. Furthermore, because the ground involves uncertainty, it is difficult to determine the penetration range of the chemicals (grouting materials). In this study, the authors carry out a seepage flow analysis of a chemical solution for a ground requiring improvement due to uncertainty. They then compare the difference in the behavior of the chemical solution between the case in which the ground is assumed to be heterogeneous and that in which it is assumed to be homogeneous.
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INTEGRATION OF SURFACE WATER MANAGEMENT IN URBAN AND REGIONAL SPATIAL PLANNING
- Article Type: Research Article
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- Pages (28-34)
- No of Download = 544
Abstract
It is necessary to analyze the conditions of the watershed hydrometry, the type of land use, the duration and the time of rain, the tidal height, which is modeled spatially, in order to support in decision making for spatial management and water management. Palembang Metropolitan City is one of the major cities on the island of Sumatra, which is regionally included in the Musi Watershed area. Hydrologically Palembang City is located at the mouth of the Musi river, with an altitude of fewer than 20 m above the mean sea level. When the maximum rainfall occurs in the watershed Area, Palembang City will be affected by tidal water, and runoff on the sub-watershed in Palembang city cannot be flowed through the main channel within Palembang City, due to the tide of Musi river water. This study aims to show the relationship between watershed hydrometry, land use change management, rain intensity, and tidal influences on the watershed area, with various scenarios that will affect the runoff discharge and distribution of inundation that occurs in the watershed area. Taking a case study of the Lambidaro sub-basin, in the Palembang City area, all sub-basin parameters that have been tested were modeled by a user flow to calculate the extent of runoff and flood flow tracking in the river. The inundation distribution occurring in the subwatershed was obtained by combining the results of hydrodynamic analysis and spatial analysis. Based on the results obtained it is concluded that there is a strong spatial relationship between land use and sub-basin morphometry and its effect on the extent of surface runoff.
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NUMERICAL ASSESSMENT OF THE IMPACT OF STRONG WIND ON THERMAL STRATIFICATION IN LAKE BIWA, JAPAN
- Article Type: Research Article
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- Pages (35-41)
- No of Download = 1039
Abstract
Water temperature near the surface of a lake increases with increasing air temperature, which results in stratification. The strength of stratification substantially influences the transport of dissolved oxygen from the surface to the bottom water of a lake. In recent years, the decrease in dissolved oxygen at the bottom of the northern part of the Lake Biwa, the largest freshwater lake in Japan, has been observed. The main cause of this is considered to be the change in stratification, which depends on weather and climate conditions. In the present study, numerical simulations were carried out to investigate the effect of strong wind on the structure of stratification in Lake Biwa. The baseline simulation was conducted using actual meteorological data, and experimental simulations were conducted using meteorological data with modified wind speed and direction. The numerical experiments showed that if the magnitude of the wind is strong enough, the stratification collapses and the wind can enhance the vertical mixing in the bottom layer even in the summer season with strong thermal stratification. In a stratified season, when the strong wind blows predominantly in one direction, the rate of the vertical mixing changes by the wind direction. Moreover, as the duration of the strong wind extends, vertical mixing easily occurs.
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COMPARISON OF DIFFERENT VEGETATION INDICES FOR ASSESSING MANGROVE DENSITY USING SENTINEL-2 IMAGERY
- Article Type: Research Article
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- Pages (42-51)
- No of Download = 633
Abstract
Vegetation mapping provides important information for understanding ecological condition through calculation of vegetation density. It based on vegetation indices developed through algorithms of a mathematical model within the visible and near-infrared reflectance bands. The index is an estimate of either leaf density per species or vegetation types, respectively. This study aimed to evaluate those indices and find the best algorithm using Sentinel-2 satellite image. Twenty four algorithms of vegetation indices were analyzed for mangrove density mapping, i.e., BR, GNDVI BR, GR, SAVI, MSAVI, NDRE, NDVI, NDVI2, NDWI, NNIP, PSRI, RR, RVI, VIRE, SVI, VIRRE, MTV1, MTVI2, RDVI, VARI, VI green, MSR, and TVI. During pre-processing stage, a digital number of a Sentinel-2 image was converted into radiance and reflectance value. The analysis resulted in three algorithms that provide the highest accuracy, i.e., NDVI (normalized difference vegetation indices) with exponential regression approach, RVI (Ratio Vegetation indices) with the exponential approach and NDVI (normalized difference vegetation indices) with a polynomial approach. The mangrove biomass spatial modeling NDVI with exponential regression approach (RMSE = 89 kg) showed the average of each pixel (10x10m) was 0.97 ton / 100 m2. Total mangrove biomass for above ground and underground vegetation in the study area was 22,365.6 tons. Sentinel-2 satellite image may best use one of those three algorithms, especially applied for mangrove vegetation.
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REDOX DISTRIBUTION PROFILES OF FLOODED PADDY SOILS WITH MICROBIAL FUEL CELL APPLICATIONS
- Article Type: Research Article
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- Pages (52-57)
- No of Download = 591
Abstract
Microbial fuel cell is one of our considerations to control denitrification redox reactions in flooded rice soils. An independent study was conducted after a nitrogen behavior study in flooded rice soils accounted for microbial fuel cell systems and microbial fuel cell systems with an externally applied voltage. External voltage was applied in the aim of increasing microbial fuel cell efficiencies, for the better control of soil redox potential. But, their redox controlling potentials and denitrification controlling were lower than that of microbial fuel cell systems. It is hypothesized, that the lower controlling potentials were due to the redox distributions effected with the distance to the anode of the circuit where the external voltage was connected through. Therefore, soil redox distributions at three depth profiles were compared in both systems and controls over the period of flooding. In external voltage applied systems, the redox potential of the soil away from anode was not much effectively controlled as of microbial fuel cell systems, although the middle soil portions near anode area were of higher redox potentials. At depths of 10 and 20 cm away from the soil surface, the redox potential increased more with MFCs and moderately with MFC-extV, but reduced with non-MFCs over the period. Accordingly, most electrons from whole soils were not freely transferred to the anode, except that from near anode areas where the external voltage was connected through. Microbial fuel cell systems with externally applied voltage had a lower impact on controlling denitrification than that of microbial fuel cell systems alone.
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NUMERICAL ANALYSIS ON MECHANISM OF LIQUEFACTION NOT ONLY IN MAIN EARTHQUAKE BUT ALSO IN AFTER SHOCK
- Article Type: Research Article
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- Pages (58-65)
- No of Download = 773
Abstract
During the 2011 Great East Japan Earthquake, liquefaction occurred in the reclaimed ground in the wide area of east Japan. In some areas, liquefaction happened in the aftershock was even more serious than what happened in the main shock. For this reason, the liquefaction that happened a long time after the earthquake caused not only by the main shock but also the multiple aftershocks within a short period of time, is intensively investigated in recent years. In this paper, particular attention is paid to the characteristic features of the liquefaction and its consequent consolidation-induced settlement. Based on the observed data, a series of dynamic-static analyses, considering not only the earthquake loading but also static loading during the consolidation after the earthquake shocks, are conducted in a sequential way just the same as the scenario of the earthquake. The calculation is conducted with 3D soil-water coupling finite element-finite difference (FE-FD) analyses based on a rotating-hardening elastoplastic constitutive model. From the analyses, it is recognized that small sequential earthquakes, which cannot cause liquefaction of a ground in an independent earthquake vibration, cannot be neglected when the ground has already experienced the liquefaction after a major shock. In addition, the aftershocks have great influence on the long-term settlement of the soil layers with low permeability. It is confirmed that the numerical method used in this study can describe the ground behavior correctly under repeated earthquake shocks.
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RESEARCH OF DAMAGED CONDITION BY THE 2016 KUMAMOTO EARTHQUAKE AND GROUND INVESTIGATION ON STONE WALLS AND ERATH STRUCTURES IN KUMAMOTO CASTLE
- Article Type: Research Article
- View Abstract
- Pages (66-72)
- No of Download = 329
Abstract
There are a lot of valuable historical structures with stone wall in Japan. Those structures are still active not only as roads and waterways, but also are designated as cultural properties, and in some places, they also play an important role as a tourism resource for the region. However, the current situation is that countermeasures against disasters are delayed like the damage of Kumamoto Castle due to the 2016 Kumamoto Earthquake. In particular, it is considered that it is important to elucidate the earthquake disaster mechanism by the interaction between the ground and the stone wall. In this research, the tendency of the damage of stone walls and earth structures will be clarified based on the survey team of the Geotechnical Engineering Society and the Kumamoto Castle Research Center, and it is discussed on the mechanism of collapse occurrence by estimating the geological structure under the several sites in Kumamoto Castle by surface wave profiling method and so on.
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SPATIAL ASSESSMENT OF THE IMPACT OF FLOOD TO MELAKA’S ECONOMY
- Article Type: Research Article
- View Abstract
- Pages (73-77)
- No of Download = 633
Abstract
Melaka used to be a significant trading state in the 16th century. It had attracted traders from various continents to be its trading partners. Many of these traders had left their footprint enormously. Over the years, these tangible and intangible historical assets have been an attraction to tourism sector which contributes significantly to Malaysian GDP. However, due to the impact of climate change and rapid urban development in Melaka, the flood has posed a risk to Melaka’s economy especially in the tourism sector. To protect its interest, Melaka has taken proactive measures in mitigating flood incidences. Thus, this study intends to examine the impact of the flood on Melaka’s economy from 2012 to 2016 using spatial assessments. This study employs a quantitative approach by using secondary data obtained from the Department of Statistics Malaysia and the Department of Irrigation and Drainage. Moran’s I, Local Indicator and Spatial Association and Bivariate Moran’s I were used to analyze the data spatially. Findings show the mitigation measures taken have relieved the risk posed by floods towards economic activities in Melaka as a whole.
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PROPOSAL OF A FLOATING-TYPE ENVIRONMENTAL PURIFICATION FACILITY INCORPORATING THE FUNCTION OF TIDELAND
- Article Type: Research Article
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- Pages (78-83)
- No of Download = 438
Abstract
Landfill in Tokyo Bay has a direct effect on the disappearance of tideland and shallow waters. Former tideland is a habitat for benthic creatures with the function of decomposing organic substances flowing out from the land area, which were eaten by small fish and served as a feeding point for migratory birds feeding them. Also, in recent years, aquatic plants such as combs forming seaweed beds are being reviewed as being superior to onshore plants in function to absorb CO2 and produce oxygen. In addition, since seaweed is also expected as a fuel for biomass power generation in recent years, this economic value is great. In other words, regenerating tidal flats and seaweed beds in Tokyo Bay will contribute not only to the environmental improvement of the sea area but also to a CO2 reduction as well as alternative energy source, which will greatly contribute to our lives. In this study, we propose a floating type purification facility incorporating the functions of tideland and shallow waters in the northwestern coast of Tokyo Bay and proposing artificial tideland and seaweed bed regeneration.
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EXPERIMENTAL STUDY ON MASONRY BUILDING STRENGTHENED WITH FERROCEMENT LAYERS
- Article Type: Research Article
- View Abstract
- Pages (84-90)
- No of Download = 538
Abstract
In the last ten years, Indonesia has suffered from moderate to severe building damages due to big earthquakes such as Yogyakarta and West Sumatra earthquakes in 2006 and 2009, respectively. Most of the damages are non-engineered buildings such as residential houses and schools, which are unreinforced masonry (URM) buildings made of brick without any reinforcements. These URM constructions are using a half clay thick brick method which is not compatible with the standards. In order to strengthen these URM buildings, a retrofitting method using ferrocement layers has been developed. An experimental study on URM building strengthened by ferrocement layers was conducted. Two specimens of a quarter scale house building models consisted of four walls with size 90cm x 110cm were constructed. The first model (M1) is the original unreinforced masonry structure with mortar plaster, and the second (M2) is the same masonry structure strengthened by providing full ferrocement layers on both sides of the walls which are acting as sandwich structures. Both specimens were tested by using a shaking table (304x190) cm2 with input motions up to 1g. The test results show that the ferrocement layers can significantly improve the performance of the URM building model and effective in preventing the collapse of masonry walls when it is shaken by earthquakes. It is concluded that this retrofitting model is applicable to retrofit the URM houses in seismic regions.
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INNOVATIVE BIFUNCTIONAL MICROCAPSULE FOR HEAT STORAGE AND ANTIBACTERIAL PROPERTIES
- Article Type: Research Article
- View Abstract
- Pages (91-98)
- No of Download = 573
Abstract
It is well known that the microcapsules encapsulating heat storage or phase change materials are coated onto the fabrics for the thermoregulating property. To increase their function on the textile application, in this work, bifunctional microcapsules having both thermal energy storage and antibacterial properties were fabricated. Chitosan was used as surfactant of poly(methyl methacrylate-divinyl benzene) microcapsule encapsulated octadecane (OD) prepared by microsuspension iodine transfer polymerization. The nonspherical with dent microcapsules were prepared in acidic condition without any free polymethyl methacrylate particles nucleated by emulsion polymerization. Due to amino groups in chitosan chains were protonated in which presented positive charge, the microcapsules stabilized with such molecules were then obtained without any coalescence. In addition, percent yield of microcapsules decreased with chitosan concentration in the aqueous medium. It may be due to the high viscosity of the aqueous medium where the monomer droplets are unable to maintain the shape in the early stage of the polymerization. For thermal properties, the latent heats of the encapsulated octadecane (234 J/g-OD) were closed to those (233 J/g-OD) of bulk octadecane. For antibacterial property, 2 millimetres over control sample of the resulting inhibition zones of both S. aureus and E. coli were observed. Based on bifunctional feature derived from both microcapsule core and shell for thermal energy storage and antibacterial properties, respectively, the developed microcapsules would express a great potential for textile application.
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KONDO THEORY FOR SPHERICAL SHELL TECTONICS
- Article Type: Research Article
- View Abstract
- Pages (99-102)
- No of Download = 328
Abstract
The buckling phenomenon of a flat or spherical shell lithosphere (tectonic plate) has been investigated in previous research. However, these studies do not give information regarding the curvature effect in the buckling phenomenon. Kondo applied Riemannian geometry to the yielding or buckling of curved materials. When the Riemannian manifold (Vn dimensional manifold) with a nonzero Euler–Schouten curvature tensor is manifested in the enveloping manifold (Euclid space: Vm dimensional manifold), the included Riemannian manifold (dimension Vn) protrudes into the enveloping manifold (dimension Vm). The curvature effect for the buckling phenomenon of materials can be formulated by a force-balance equation from mechanics and the Euler–Schouten curvature tensor from differential geometry. In this paper, using the Euler–Schouten curvature tensor from differential geometry, the authors derive a formulation for the buckling phenomenon with the curvature effect for a spherical shell lithosphere as a buckling equation with high-order strain for lithosphere deformation.
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STABILITY ANALYSIS FOR AN AIRPORT EMBANKMENT, EVALUATING SHORT AND LONG TERM TECHNIQUES
- Article Type: Research Article
- View Abstract
- Pages (103-108)
- No of Download = 566
Abstract
This article discusses the stability analysis corresponding to the construction project of a runway embankment over the soft clay, to reach the subgrade level, that confirm the foundation of the runway No. 16/34, for the project Aeropuerto International de Chincheros Cusco - Peru (AICC). The safety analysis consists in evaluating the strength reduction of the foundation, considering the effect of the consolidation, for the short-term and long-term construction techniques considering the soil improvement with preloading, vertical geo-drains and stone columns techniques. The numerical analysis is developed with the Plaxis 2D v8.6 software, considering a typical section corresponding to a critical sector, located on the km 1+180 progressive of the landing strip. According to the results of the definitive geotechnical study, the foundation soil, corresponding to the analysis section, is a saturated soft clay, until a depth of 35 m; then to model its mechanical behavior was used the Soft Soil Model; and for the embankment, that will be constructed of compacted soil obtained from the ground cutting process, was considered the Mohr-Coulomb model. The physical and mechanical parameters were established based on the results of field and laboratory test, correlations and referential values established in the specialized bibliography. From the comparative results based on the calculated safety factors, the stone columns technique presents a higher factor of safety compared to the preloading and vertical geo-drains techniques; while considering the short-term construction, the foundation soil fails due to loss of strength before reaching the total embankment height.
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THE PERFORMANCE RAINFALL DURING RAINY SEASONAL OVER THAILAND BY USING PRELIMINARY REGIONAL COUPLED ATMOSPHERIC AND OCEANIC (WRF-ROMS) MODEL
- Article Type: Research Article
- View Abstract
- Pages (109-115)
- No of Download = 366
Abstract
A coupled regional climate between atmosphere-ocean coupled model systems is developed using the regional model Weather Research and Forecasting (WRF) and Regional Ocean Modeling System (ROMS) to simulate performance rainfall during the rainy season over Thailand. The processes of the atmospheric model are provided to the ocean model. The wind (Uwind, Vwind), the atmospheric pressure (Patm), the relative humidity (RH), the atmosphere surface temperature (Tair), the cloud fraction (Cloud), precipitation (Rain), the short wave (SW), the long wave (LW). The processes of the oceanic model provide sea surface temperature (SST) to atmosphere model. The simulation period is during June-July-August (JJA) in 2014, and the results are compared with rainfall gauge station from Thai Metrology Department (TMD). The results show a good trend performance rainfall and can capture large amount rainfall in June, July and JJA 2014. The average rainfall and Mean Absolute Error (MAE) showed good value in June, July and JJA 2014, especially in June was shown good value average (236.25 mm) and MAE (4.389) than other months.
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INVESTIGATION OF RUTTING PERFORMANCE OF DIFFERENT WARM MIX ASPHALT (WMA) MIXTURES
- Article Type: Research Article
- View Abstract
- Pages (116-123)
- No of Download = 646
Abstract
Use of warm mix asphalt (WMA) in pavement industries has been growing rapidly over last decade because it can lower down the construction temperature and subsequently reduces the environmental pollution and energy consumption. There are mainly two different types of WMA technology are available: water-based foaming and chemical additives. One of the challenges to WMA technology, the uncertainty about the performance of WMA mixtures is still unclear. To this end, this study investigated the rutting performance (one of the major distresses) of mixtures with different WMA additives. Rutting performance of WMA mixtures with four different additives (Terex® foaming, Evotherm®, Cecabase®, and Cecabase®+) was evaluated and compared with the control (un-modified) hot mix asphalt (HMA) mixture through Hamburg wheel track test (HWTT). Results showed that all WMA mixtures have lower rut depth compared to control HMA mixture. It is also observed that Terex® and Cecabase® samples exhibited better rutting resistance than Evotherm® sample. However, Cecabase®+ WMA sample showed significant enhancement in rutting resistance due to the presence of polymer. In addition to mixture test, extracted binders from these mixtures were also evaluated though Superpave performance grade (PG) and multiple stress creep-recovery tests. The performance orders of the extracted binders from these two tests are also similar as the mixture performance. This study also found that non-recoverable compliance (Jnr) value obtained from the MSCR test demonstrated better correlation with HWTT (R2 = 0.96) compared to Superpave rutting parameter (R2 = 0.68).
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MECHANISTIC BEHAVIOR OF OPEN AND DENSE GRADED UNBOUND GRANULAR MATERIALS UNDER TRAFFIC LOADS
- Article Type: Research Article
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- Pages (124-129)
- No of Download = 584
Abstract
The absence of abundant amount of natural unbound granular materials (UGMs) necessitates investigating alternatives such as processed crushed rock. Extensive use of crushed rock in pavement design requires proper modification of characterization, design and construction practices. Many specifications and standards require adopting of dense gradation of base materials. Although dense gradation has a high dry density, it also has low permeability or voids. This low permeability results in a decrease in material strength when the pavement is exposed to moisture. This research examines the effects of fines content on mechanistic behaviors of UGMs, particularly resilient modulus (Mr) and permanent deformation (PD) using repeated load triaxial test (RLTT). Class 2 crushed rock is used in two gradations- dense gradation and open gradation. Results from RLTT show that open graded Class 2 has an acceptable PD resistance under repeated loads for test’s Stages 1, 2 and 3 followed by a significant collapse at Stage 4 as per Australian pavement design guide. This investigation has found that open graded Class 2 has higher Mr than dense-graded Class 2. This paper suggests that open graded Class 2 could be used as a porous base material for roads with low traffic volumes.
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STUDY ON EXTRACTION AND ADSORPTION OF CESIUM FROM VERMICULITE MIXTURE SAND
- Article Type: Research Article
- View Abstract
- Pages (130-135)
- No of Download = 588
Abstract
A large amount of radioactive materials were diffused by the accident at Fukushima Daiichi nuclear power station of Tokyo electric power company, and decontamination has been continued for about six years in Fukushima. The contaminated soil that is stripped on the ground and is collected should be reduced in volume at an intermediate storage facility. However, it takes a long time to operate the facility. The ministry of the environment shows the guidelines that it is possible to dispose of the radioactive waste below 8000Bq/kg of radiation dose in an ordinary process. Therefore, it is more desirable that the radiation dose should be reduced below 800Bq/kg in flexible containers filled with contaminated soil than the reduction of radiation dose in the intermediate storage facility. Thus, in this study, the method in which only radioactive materials are collected from the contaminated soil in the flexible containers is proposed. The extraction of radioactive cesium from the soil is investigated so as to check the performance and availability of the proposed method. As a result, it is confirmed that is possible to collect a certain amount of cesium from the cohesive soil like vermiculite in which cesium is strongly fixed.
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STUDY ON REMOVAL METHOD OF CESIUM FROM SLOPE SOIL USING SIMPLE SLUSHER
- Article Type: Research Article
- View Abstract
- Pages (136-143)
- No of Download = 583
Abstract
Though 6 years passed since the accident at the Fukushima Daiichi nuclear power station, and the decontamination of the difficult-to-return zone is not in prospect. The reason why the decontamination has not carried on is that of the geographic factor around the zone. In particular, there is a lot of forest area around the zone. Since the accident, radioactive cesium has been accumulated by constant wind and rainfall. Therefore, it is necessary to decontaminate the slope as it is the supply source of radioactive cesium from the forest to the residential area or farmland. Thus, in this study, the simple method of using running water was proposed to solve the decontamination of the forest area. This method proves that the vermiculite strongly fixes the radioactive cesium and the decontamination site is a slope. As a result, it is confirmed that the removal of vermiculites reduces 20% of the volume of contaminated soil. The vermiculite is easy to remove from the water since it is lighter in weight than sand and water. Removal of vermiculite using this method leads to volume reduction of the contaminated soil.
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COMPRESSION BEHAVIOUR OF HIGHLY EXPANSIVE CLAYS STABILISED WITH A GREEN STABILISER OF MAGNESIUM CHLORIDE
- Article Type: Research Article
- View Abstract
- Pages (144-150)
- No of Download = 650
Abstract
The presence of expansive clays underlying infrastructures has been responsible for damages to the structures in many cases all over the world when the moisture content of these problematic soils changes. One of the effective methods to alleviate the swell potential of expansive clays is to stabilize them with an additive such as lime, cement, resins, chemicals and so on. In this study, the use of magnesium chloride (MgCl2) as a green stabilizer to improve the geotechnical properties of the treated clays has been investigated by conducting several laboratory tests. Currently, MgCl2 is mainly used as an anti-icing material in pavement industry; however, it has been recently received more attention as a stabilizer for clayey soils. Firstly, the effect of MgCl2 on the consistency limits of the treated clayey soils was studied in this study. Next, the swell pressure and free swell strain of the treated samples were measured and the results compared with one of the untreated samples. Overall, the results state that even a small dose of MgCl2 can be used as a stabilizer for expansive clays to improve the geotechnical properties considerably and to mitigate their swell potential effectively.
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NON-REINFORCED FOAM FILLED MODULES FOR RAPIDLY ASSEMBLED POST DISASTER HOUSING
- Article Type: Research Article
- View Abstract
- Pages (151-161)
- No of Download = 755
Abstract
Rapidly assembled structures play an important role in post-disaster housing. This research study introduces a modular non-reinforced foam-filled system for rapidly assembled buildings and studies its structural performance. A novel structural modular construction system using pneumatic formwork is presented and its structural performance as a post-disaster housing system is studied. To that end, this paper presents a numerical analysis using finite element modeling on the foam-filled modular units, together with a set of experimental tests on the elements. Finally, the performance of a real size module made of polyurethane AUW763 against snow and wind loads in critical areas is modeled, using the software ROBOT 2016 and ANSYS. The results demonstrate that the foam-filled modular units successfully meet the standards’ requirements for semi-permanent housing even in cyclonic prone areas based on Standards Australia (AS1170.2), International Building Code (IBC-2015) and an American standard as Minimum Design Loads for Buildings and Other Structures (ASCE7-10).
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METHOD TO ESTIMATE THE SYSTEM PROBABILITY OF FAILURE FOR SLOPE STABILITY ANALYSIS
- Article Type: Research Article
- View Abstract
- Pages (162-169)
- No of Download = 678
Abstract
Uncertainty in soil slope is one of the problems in slope stability analysis because natural soil slope is heterogeneous that is difficult to predict time and location of the failure. This problem leads that only conventional approaches do not take into account many risks related to slope safety. The optimization of this problem is carried out using probabilistic slope stability analysis. This paper described a method to calculate the probability of failure of slope stability analysis. The system probability of failure is defined as the complement of the sum of the probability of failure corresponding to sliding failure. Furthermore, this paper shows time-steps in the developments of factors of safety in soil slope and perform natural slope stability analyses by probabilistic approach on a hill range. Sensitivity result indicated that the effective angle of internal friction (φ) and the angle of soil slope (β) are most significant parameters and choose to be random variable parameters. Probabilistic for soil slope failure is calculated using conventional design equations, mean and coefficient of variation values for the random variable parameters as input. GeoStudio’s program (SEEP/W and SLOPE/W application) have been employed to describe the process of rainfall infiltration under positive and negative pore-water pressures and slope stability analyses, respectively. Bishop’s simplified method was used in conjunction with Monte Carlo Simulation to determine in term of the probability of failure (Pf). This approach is to prove the best confidence result in slope stability analysis.
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EXPERIMENTAL STUDY OF GEOTECHNICAL CHARACTERISTICS OF CRUSHED GLASS MIXED WITH KAOLINITE SOIL
- Article Type: Research Article
- View Abstract
- Pages (170-176)
- No of Download = 660
Abstract
The Geotechnical properties of adding crushed curbside-collected glass to Kaolinite S300 with various percentages of 10 to 50% were experimentally evaluated. Crushed glass passing the 2.36 mm (#8) sieve, and retaining on 1.18 mm (#16) selected for this study is collected from a different area in Johor Bahru, Malaysia. Measured hydraulic conductivities were on the order of 2.33E-6 and 1.87E-5 for 10% and 50% respectively. The result shows increment in the maximum dry density from 1.615 mg⁄m3 at 10% to 1.908 mg⁄m3 at 50% of addition of crushed glass with the optimum moisture content of 18.35% and 7.4% respectively. Friction angles from the direct shear test were evaluated between 12 to 25 degrees at normal stresses of 56.4 to 219.9 kPa. The result shows that the unconfined compression strength of Kaolinite S300 mixed with crushed glass is increased from 5.26 kPa at 10% addition of crushed glass up to 17.52 kPa at 50%. It can be concluded that the crushed glass is environmentally clean, readily available, and relatively low-cost material that can be one of the replacements for traditional aggregate to enhance the geotechnical properties of soft cohesive soils.
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ROAD SAFETY ANALYSIS IN THAILAND AND OTHER ASIAN COUNTRIES: URGENT ACTIONS FOR THAILAND
- Article Type: Research Article
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- Pages (177-183)
- No of Download = 712
Abstract
One of the most important prerequisites to achieving challenging sustainable development goals (SDG) on road safety is to comprehend the interrelationship of constituents related to road safety such as road traffic fatalities (RTFs), population, income levels, registered vehicles, law enforcement and others. A comprehensive review and critical analysis of road safety status in Thailand and other Asian countries were completed. It was found that RTFs per 100,000 people had no correlation with GNI per capita, while RTFs per 1,000 vehicles revealed reasonable correlations with the number of registered vehicles per 1,000 people. As the number of registered vehicles per 1,000 people increased, the RTFs per 1,000 vehicles decreased. The main cause of RTFs in Thailand and several Asian countries were 2/3-wheelers. As the proportion of 2/3- wheelers in Asian countries increased, the percentages of RTFs caused by 2/3-wheelers were enhanced. When the GNIs of any Asian country increased, the performances of the national road safety law enforcement were generally improved. Based on RTFs per 100,000 people, Thailand was one of the most dangerous road transport countries on earth. Finally, when the various main causes of road accidents in Thailand were identified, urgent road safety actions were proposed accordingly.
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HEAVY RAINFALL CHARACTERISTICS AT SOUTH-WEST OF MT. MERAPI- YOGYAKARTA AND CENTRAL JAVA PROVINCE, INDONESIA
- Article Type: Research Article
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- Pages (184-191)
- No of Download = 606
Abstract
Heavy rainfall analysis is an important data for disaster management of flash floods and debris flows in mountainous areas. Those disasters may cause casualties and property damages. It is an urgent consideration to analyze the heavy rainfall characteristics in the area in order to gain well-planned disaster mitigation. Hourly rainfall data were analyzed over Mt. Merapi area especially those which are located in the Yogyakarta and Central Java Province. The rainfall data were collected from a number of automatic rainfall stations with 11 to 28 years of data length. Heavy rainfall is defined when the rainfall depth exceeds 50 mm per event. Heavy rainfall analysis in the study area indicates that heavy rainfall varies among the stations and it is likely occurred more often at the south-west of Mt. Merapi. Statistical analysis gives that maximum rainfall depth for an event varies from 99 mm in the south-east area to 282 mm at the south-west area of Mt. Merapi. Maximum rainfall intensity values show that at the south-west of Mt. Merapi have higher rainfall intensity than at the south-east area. The results indicate that orographic effects and west monsoon are important in determining the spatial distribution of heavy rainfall occurrences in Mt. Merapi area. Besides, heavy rainfall more frequent occurred from noon until late afternoon. The annual maximum heavy rainfall data at the south-west of Mt. Merapi was best fitted with the LN3 distribution.
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NUMERICAL MODELING FOR THE SELECTION OF EFFLUENT OUTLET LOCATION
- Article Type: Research Article
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- Pages (192-201)
- No of Download = 837
Abstract
This paper presents the hydro-environmental sustainability study of a planned mill in the Muan and Riko River area, Province of East Kalimantan, Indonesia. The study aims to choose the best location among the three options for the mill’s water effluent outlet in Muan River. The surface-water modeling system is used to numerically model sedimentation patterns due to the placement location of the water intake and effluent outlet for the prospective mill. The model inputs are tidal propagation and river discharges from the tributaries. A field measurement is also carried out to provide solid data for the model construction and validation. The model shows a good agreement with the field data, with errors below 5%. It is found that the pattern of bed elevation change is closely affected by the location of the outlet, with a maximum yearly bed change of 1.4 m. The scenario where the effluent outlet is placed at the upstream of Muan River shows the lowest bed change along Muan River. However, dredging measures to maintain the river depth is required to make sure that the river remains accessible for water transportation.
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APPLICATION OF MULTIVARIABLE REGRESSION MODELS FOR PREDICTION OF COMPOSITE NANOSILICA/POLYMER ASPHALT MIXTURE OBC
- Article Type: Research Article
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- Pages (202-209)
- No of Download = 620
Abstract
In this research, the effects of nanosilica particles and polymer on conventional properties of hot mix asphalt have been investigated. The study also investigates the application of various regression models for the prediction of optimum binder content (OBC). The proposed models use values for stability and flow obtained from Marshall test results. The asphalt binder was modified using polyethylene and polypropylene polymers with varying percentages of nanosilica. The fundamental mechanical and physical properties of composite nanosilica/polymer modified binder and aggregate-binder mixtures were estimated through penetration, softening point, rolling thin film oven tests (RTFOT) aging and Marshall test. The results show that application of nanosilica improves the stability, reduces optimum binder content (OBC), increases stiffness as well as strength characteristic of the asphalt mixtures. The regression models analyzed was found to yields good predicted values with a high coefficient of determination R2 and very low percentage errors of less than 5%.
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IMPACTS OF DISPUTE ON PROJECT COST: CONTRACTORS’ PERSPECTIVE
- Article Type: Research Article
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- Pages (210-221)
- No of Download = 319
Abstract
This research aims to investigate impacts of construction disputes driven by particular root causes on the project cost faced by Thai contractors. Both qualitative and quantitative research methodologies were employed in order to achieve the study goals. Individual in-depth interview as a qualitative method was used to comprehend dispute evolution and its impact. Factor analysis and relative importance index were respectively used to categorize and quantify priorities. Results show that there are 17 significant root causes. They had been grouped into 3 categories, namely “Project owners’ withholding payment and defective construction documents”, “Contractors’ inadequate and incompetent project staff and workers”, and “Contractors’ inefficient project management”. Ranking of each factor group was then explained according to its importance level on the impact of the project cost. The category of “Project owners’ withholding payment and defective construction documents” was found to be the most important. After that, discussion and recommendations were asserted to eliminate, minimize, and control the non-value-added costs of the project budget.