Articles

  1. PERMEABILITY AND CONSOLIDATION BEHAVIOR OF COMPOSITE GROUND REINFORCED WITH SAND COLUMNS Download Article

    B. A. Mir and Ashish Juneja
    • Article Type: Research Article
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    • Pages (832-839)
    • No of Download = 1815

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    In this paper, the behavior of the composite ground reinforced with sand columns with and without smear effect installed in 200mm long and 100mm diameter cylindrical clay specimens was investigated using conventional triaxial consolidation tests under different confining pressures ranging from 50kPa to 575kPa. Change in volume of the specimen was measured using automatic volume change apparatus. This typically required a consolidation time of about 100minutes compared to more than 6-7days required to consolidate the specimen without the sand columns. However, specimens prepared with smear effect took slightly more time to consolidate thereby lending further confidence to the method used to create the smear zone. The test results showed that the dissipation of excess pore water pressure occur faster in the radial direction due to the greater coefficient of soil permeability in the horizontal direction and the reduced drainage path.

  2. SUB-DARCY-SCALE MODELING OF NON-UNIFORM FLOW THROUGH POROUS MEDIA WITH MIXED WETTABILITIES Download Article

    Junichiro Takeuchi, Takuya Takahashi and Masayuki Fujihara
    • Article Type: Research Article
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    • Pages (840-847)
    • No of Download = 946

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    A physically-based conceptual model is developed using spatially distributed sub-Darcy-scale clusters in a regular grid to reproduce both the hydraulic properties and the non-uniform wetting and drainage fronts through porous media mixed with hydrophilic and hydrophobic grains. In the model, cellular automaton-like algorithm is employed to route water- and air-intrusion paths through the mixed porous media. Water retention characteristics, which are ones of the macroscopic properties of porous media, are estimated by accumulating a certain numbers of clusters after reaching equilibrium states in a wetting or drainage process. In the experimental part of this study, normal (hydrophilic) and artificially hydrophobized glass spheres, whose diameter is about 0.2 mm, are used as materials, and hydraulic properties of homogeneously mixed glass spheres with various rates are measured. The measured data are compared to model estimation, and the availability of the model is shown.

  3. PORE PRESSURE RESPONSE OF CLAYEY SEABED UNDER OCEAN WAVE Download Article

    Yuchen Wang, Erwin Oh and Shan-Chun Chang
    • Article Type: Research Article
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    • Pages (848-858)
    • No of Download = 788

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    In this study, a 2-D quasi-dynamic u-w-p model is developed to examine the wave-induced clayey seabed behavior. Further, this paper aims to provide a better understanding of the unstable condition of clayey seabed in the vicinity of coastal structure. In the proposed u-w-p model, acceleration, velocity, and displacement terms are considered different for both solid and fluid phases. The governing equations of u-w-p model are determined from constitutive law and conservation law under certain assumptions. The numerical solutions are developed by using Finite Difference Method (FDM) and three outputs (pore water pressure, effective vertical stress and shear stress) are analyzed. The result shows that both liquefaction and shear failure have low potential to occur in clayey seabed, this is due to by the soil structure and low permeability of clay. The pore water pressure vary linearly according to the depth, however, this variation is not significant in clayey seabed. In addition, there is no phase lag in clayey seabed. This paper presents the findings on wave induced stress variation in seabed with fine-grained soil, which differs to some of the published literature on sandy seabed.

  4. REACTION BEHAVIOR OF C6H6 IN THE THREE-WAY CATALYTIC CONVERTER EQUIPPED A GASOLINE ENGINE Download Article

    Akio Takigawa, Akihiro Mieda and Yongzhen Peng
    • Article Type: Research Article
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    • Pages (859-863)
    • No of Download = 740

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    The reaction behavior of C6H6 was investigated in a tubular-flow reactor containing a three-way catalyst. Experiments were performed to investigate the effects of coexistence gas components, temperature, gas flow rate and operating age of catalytic converter. The components of C6H6, H2, CO, H2O, HC, O2 and N2 were selected from the gasoline engine exhaust gas. The experimental results show that the oxidation of C6H6 was enhanced by the presence of O2 and CO, while the presences of H2, HC and H2O have suppressive effect on the oxidation of C6H6 than O2 and CO. The results reveal that catalyst has lower catalytic oxidation activity for C6H6 oxidation at lower temperature, and has higher catalytic oxidation activity for C6H6 than CH4, C2H6 and C3H8, and decomposition of C6H6 via catalyst was similar to the decompositions of C2H4 and C3H6. The operating age of catalytic converter has lower effect on the oxidation of C6H6 with an increase in the operating time of catalytic converter from 0 to 80,000km.

  5. OPTIMAL GRONDWATER MONITORING NETWORK DESIGN FOR POLLUTION PLUME ESTIMATION WITH ACTIVE SOURCES Download Article

    Bithin Datta and Deepesh Singh
    • Article Type: Research Article
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    • Pages (864-869)
    • No of Download = 754

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    A new methodology has been developed to design optimal monitoring network to estimate the transient pollution plume resulting from active pollution sources in a contaminated aquifer. An optimization algorithm is linked with geostatistical kriging model as well as a numerical simulation model. Simulated annealing is used as the optimization tool. The physical process in the aquifer, i.e., the flow and contaminant transport processes are numerically simulated using numerical groundwater flow and transport simulation models. The spatial extrapolation of measured and simulated concentration is performed by using geostatistical estimation based on Kriging. The objective is to minimize the mass estimation error. The developed methodology is evaluated for an illustrative study area.

  6. MICROSCOPIC RANGE OF IMMOBILIZATION BETWEEN HEAVY METALS AND AMENDMENT IN SOIL THROUGH WATER MIGRATION Download Article

    Shouhei Ogawa, Masahiko Katoh and Takeshi Sato
    • Article Type: Research Article
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    • Pages (870-877)
    • No of Download = 699

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    In order to identify the microscopic range of immobilization in soil, the pot test was conducted to evaluate the distance that lead (Pb) and antimony (Sb) transport through water migration and the transport phases during immobilization. The amount of amendment required to immobilize Pb and Sb was investigated on the basis of the microscopic range of immobilization. The results clearly showed that Pb and Sb were transported a maximum of 5 mm and 6 mm, respectively, through water migration which corresponded to precipitation for one month. Both metals were accumulated 1 mm from contaminated soil. The primary Pb transport phase was sorbed on Fe/Mn oxide, while that of Sb was water-soluble. The amount of amendment required for Pb and Sb immobilization was estimated to be 4.62% (w/w) from the microscopic range of immobilization (1 mm).

  7. STRENGTH ASSESSMENT OF CEMENT TREATED SOIL-RECLAIMED ASPHALT PAVEMENT (RAP) MIXTURE Download Article

    Jirayut Suebsuk, Aniroot Suksan and Suksun Horpibulsuk
    • Article Type: Research Article
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    • Pages (878-884)
    • No of Download = 5731

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    The article attempts to present the influence of reclaimed asphalt pavement (RAP) content on the compaction behavior and unconfined compressive strength of cement treated soil-RAP mixture. The laboratory compaction and unconfined compression tests on cement treated soil-RAP mixture were carried out with various RAP and cement contents. The porosity was adopted as a state parameter for assessing the strength of the mixed materials. The results show that with an increase in RAP content, the OMC tends to decrease, up to the optimum of soil/RAP ratio of 50/50. The asphalt fixation point is designated as a transitional point where a small change in strength turns to a larger change. An asphalt content of 3.5% (50/50 soil/RAP ratio) is found to be the asphalt fixation point. The strengths, where the asphalt content is lower than the asphalt fixation point, can be predicted by the proposed generalized form of strength. This proposed equation can assess the laboratory strength of cement treated soil-RAP mixture under various mixed proportions, cement contents, water contents, and curing times.

  8. THE RELATION BETWEEN ROAD CRACK VEGETATION AND PLANT BIODIVERSITY IN URBAN LANDSCAPE Download Article

    Taizo Uchida, JunHuan Xue Daisuke Hayasaka, Teruo Arase, William T. Haller and Lyn A. Gettys
    • Article Type: Research Article
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    • Pages (885-891)
    • No of Download = 796

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    The objective of this study is to collect basic information on vegetation in road crack, especially in curbside crack of road, for evaluating plant biodiversity in urban landscape. A curbside crack in this study was defined as a linear space (under 20 mm in width) between the asphalt pavement and curbstone. The species composition of plants invading curbside cracks was surveyed in 38 plots along the serial National Route, over a total length of 36.5 km, in Fukuoka City in southern Japan. In total, 113 species including native plants (83 species, 73.5%), perennial herbs (57 species, 50.4%) and woody plants (13 species, 11.5%) were recorded in curbside cracks. Buried seeds were also obtained from soil in curbside cracks, which means the cracks would possess a potential as seed bank. Incidentally, no significant differences were found in the vegetation characteristics of curbside cracks among land-use types (Kolmogorov-Smirnov Test, P > 0.05). From these results, curbside cracks would be likely to play an important role in offering habitat for plants in urban area.

  9. ASSESSMENT OF CHROMIUM CONTAMINATION IN SEDIMENTS OF SOUTHERN KAOHSIUNG HARBOR, TAIWAN Download Article

    Cheng-Di Dong, Chih-Feng Chen and Chiu-Wen Chen
    • Article Type: Research Article
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    • Pages (892-896)
    • No of Download = 544

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    Major objectives of this study are to evaluate the enrichment, accumulation, and potential ecological risk of chromium (Cr) in the surface sediments of southern Kaohsiung Harbor, Taiwan. Twelve sampling locations were installed of southern Kaohsiung Harbor to collect sediment samples for analyzing Cr. Results showed that the Cr concentrations varied from 13.4–265.7 mg/kg with an average of 53.2±71.2 mg/kg. The spatial distribution of Cr reveals that the Cr concentration is relatively high in the river mouth region, especially in Jen-Gen River, and gradually diminishes toward the harbor entrance region. This indicates that upstream industrial and municipal wastewater discharges along the river bank are major sources of Cr pollution. Results from the enrichment factor and geo-accumulation index analyses imply that the sediments collected from the river mouth can be characterized between severe and very severe degree enrichment and between moderately strong and strong to very strong accumulation of Cr, respectively. However, results of potential ecological risk index indicate that the sediment has low ecological potential risk.

  10. CONSTRUCTION AND MAINTENANCE OF EMBANKMENTS USING HIGHLY ERODIBLE SOILS IN THE PILBARA, NORTH-WESTERN AUSTRALIA Download Article

    J.V. Smith and L.A. Sullivan
    • Article Type: Research Article
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    • Pages (897-902)
    • No of Download = 1299

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    Many soils and sediments in the Pilbara region of north-western Australia are highly susceptible to erosion.  arge quantities of construction materials are required as iron ore mining and the extensive railway lines used to transport ore to port continue to be developed in the region. Simply avoiding the use of highly erodible materials is often considered to be too high a cost where alternatives are scarce. Constructing embankments to survive the cyclonic wet season from material highly susceptible to erosion, is a major challenge. Highly erodible materials encountered in the Pilbara include some bedrock shales, dispersive alluvial silts and sands and slaking clays and mudstones. Dispersive materials can erode internally by the formation of pipes or tunnels. Piping erosion can be difficult to detect and can cause severe internal damage to embankments before being detected. Similarly, slaking material can undergo compaction during wetting and drying cycles resulting in unexpectedly large settlements. The effect of erosion, in general, is controlled by appropriate embankment design and construction, in particular compaction standards. Erosion controls include sacrificial batters, surface protection, encapsulation and stabilisation. For many mining projects achieving short-term construction deadlines is a high priority and adding erosion control measures after construction may be preferred. Predicting the time by which erosion control needs to be installed or rehabilitated should be a part of the embankment design process. Material selection has direct implications for the on-going asset management of embankment structures.

  11. EARTH MASONRY UNIT: SUSTAINABLE CMU ALTERNATIVE Download Article

    Joseph Dahmen, Jose F. Muñoz
    • Article Type: Research Article
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    • Pages (903-909)
    • No of Download = 931

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    This paper provides a justification for a masonry building block fabricated from soil materials that could radically improve the environmental profile of concrete masonry. Conventional concrete masonry units depend on the reaction of ordinary Portland cement to provide strength and durability. While effective at meeting structural requirements, a study has shown that production of ordinary Portland cement causes 6-7% of global greenhouse gas emissions. In contrast, the principal component of stabilized earth mix designs is soil, a ubiquitous, innocuous, and almost unlimited resource that offers the potential of sustainable cradle-to-cradle environmental performance over a full life cycle of products. The paper presents research investigating the characteristics of a range engineered soil blends and natural soil sources. The research is applied toward the production of an environmentally sustainable stabilized earth masonry building block capable of meeting current ASTM concrete block performance specifications while reducing embodied energy by as much as 50% due to the reduction of energy-intensive Portland cement binders, dramatically reducing CO2 emissions of one of the most common construction materials on the planet.

  12. CHARACTERISTICS OF WATER-SWELLING FRICTION REDUCING MATERIALS ON THE PULLING-OUT REMOVAL OF TEMPORARY WORKS Download Article

    Shinya Inazumi, Hsin Ming Shang, Yoshihiro Nakagishi and Hideo Kawabata
    • Article Type: Research Article
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    • Pages (910-918)
    • No of Download = 759

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    Water-swelling friction reducing materials (WSFRMs) are commonly used as a “pulling-out assisting material” for temporary works such as steel sheet-piles and H-steels that are required to be removed and collected after use. Generally, WSFRMs are coated to steel sheet-piles and H-steels before these are driven into the ground or placed in mortar fluid. The WSFRMs absorb moisture in the ground or mortar to swell and form a swelling membrane over the piles. Then, the membrane works also as a lubricating membrane and as a result it can reduce friction. The authors pay attention to these characteristics of WSFRMs and try to develop a special material that can swell only when soaked in an alkaline moisture environment without swelling in acid or a neutral water environment, in addition to the conventional material that swells in any type of moisture environment. In this paper, considering that both types (alkaline and conventional) of WSFRMs are used as “pulling-out assisting material” for temporary steel sheet-piles and H-steels, we perform through experiments on the swelling ratios of the materials as well as on the pulling-out characteristics of the steel flat-bar to which the WSFRMs are coated in advance.

  13. STABILITY ANALYSIS OF AN EARTH DAM FOUNDATION IN TUNISIA Download Article

    El Ouni Mohamed Ridha and Guettaya Ikram
    • Article Type: Research Article
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    • Pages (919-926)
    • No of Download = 382

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    Soil liquefaction has been the cause of most geotechnical hazards during earthquake events. Its assessment is an important design consideration for structures made on sandy deposits and situated in seismically active regions. The present paper focuses on the analysis of soil liquefaction potential beneath an earth dam in Tunisia using in situ and laboratory tests results. In order to precise the need of a planned construction, site characterization was carried out with in situ tests (CPT) performed at the dam site before and after vibrocompaction technique. In situ - based simplified procedures have been applied using the data collected before and after the soil densification and the results are so analyzed. Furthermore, the laboratory study includes cyclic triaxial testing of samples retrieved at different densities, confining stresses and cyclic stress ratios and the results were discussed. The obtained results showed a general agreement between the two types of approaches.