Articles

  1. PREDICTING THE STRESS-STRAIN BEHAVIOR OF MINE TAILING USING MODIFIED HYPERBOLIC MODEL Download Article

    Mary Ann Q. Adajar and Mark Albert H. Zarco
    • Article Type: Research Article
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    • Pages (1834-1841)
    • No of Download = 914

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    The shear strength behavior of mine tailings was investigated through direct shear test to determine its applicability as embankment material.   Dry tailings at very dense initial state and lower normal stresses exhibited peak shear strength and strain softening with dilative behavior, indicating that tailing samples failed in brittle manner.  At higher normal stresses, the dry tailing samples attained the critical state shear stress and the volumetric strain is purely compressive.  Tailings in dry condition manifested a strong particle interlock as indicated by high critical state friction angle ranging from 36.6º to 38.4º.  Peak shear stress was not observed for saturated tailings even at very dense condition and low normal stresses indicating that saturated tailings have ductile behavior with contractive volumetric strain.   Friction angles at failure of saturated tailings were lower at an average of 4o as compared to those obtained in dry condition.  Modified hyperbolic model was formulated to predict the shear stress against shear strain and volumetric strain against shear strain responses of tailings to different stresses.  The modified hyperbolic model provides a good approximation to the stress-strain and volumetric strain-shear strain responses measured during the tests of tailings that exhibited a ductile failure and compressive volumetric strain.  However, the model does not give a good prediction of stress-strain response for specimens that exhibited brittle failure with dilative volumetric strain.  The model cannot capture the strain softening phenomena, but it can be used to model the behavior leading to the strain softening as well as during the ductile stage.  

  2. NEW MICROBIAL-FUNCTION-BASED REINFORCEMENT METHOD FOR EMBANKMENT Download Article

    Toshiro HATA, Kazuhiro KANEDA and Tomohiro TANIKAWA
    • Article Type: Research Article
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    • Pages (1842-1847)
    • No of Download = 769

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    In recent years, erosion control has been increasingly implemented for land embankments of public roadways (e.g., express highways). In the field of geo-environmental engineering, it is important to develop an easy-to-use maintenance method for such embankments based on a natural process. This study aims to develop an eco-friendly and inexpensive maintenance method for embankment management. In this paper, the general concept of the newly proposed method is presented based on the results of laboratory tests and numerical simulations. The most important advantage of this method is the enhancement of urease activity in the in-situ microorganism community. Laboratory tests showed that microbial carbonate precipitation (MCP)-treated sand can increase the liquefaction strength. The numerical simulation results show that an MCP-treated embankment surface shows a rigid frame structure. These results show that the proposed method is suitable for use as an embankment maintenance method.

  3. ROAD SUBMERGENCE DURING FLOODING AND ITS EFFECT ON SUBGRADE STRENGTH Download Article

    Abdul Naser Abdul Ghani, Nur Izyan Roslan and Ahmad Hilmy Abdul Hamid
    • Article Type: Research Article
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    • Pages (1848-1853)
    • No of Download = 828

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     Deterioration of road structural integrity because of flooding may cause huge expenditure for rehabilitation and maintenance of roadway. In principle, the design of pavement structure is based on the strength of compacted soil known as the subgrade or road foundation. Therefore, subgrade is a significant part of the road structural system. When roads are inundated for a long time or repeatedly, the materials in each layer of road structure become saturated, and the original condition of subgrade soils will be compromised. This study investigated the effect on sub-grade strength and properties due to road submergence period and repeated submergence of the road structural systems. Two types of soil that are normally used as the embankment material in road construction, which can be categorized as cohesive and cohesionless materials, were used in this study. California Bearing Ratio (CBR) test and consolidation settlement test were carried out on various categories of inundation and loading conditions including repeated inundation. The findings indicated that the strength of subgrade soil further decrease when they are inundated for a longer period. Similarly, consolidation test also shows that a quick and higher settlement could occur when the soil is inundated for a longer period. These findings are useful for road design and maintenance strategies of flood affected road links.

  4. QUANTIFICATION OF MACRODISPERSION IN LABORATORY-SCALE HETEROGENEOUS POROUS FORMATIONS Download Article

    Kazuya INOUE, Tomoki KURASAWA and Tsutomu TANAKA
    • Article Type: Research Article
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    • Pages (1854-1861)
    • No of Download = 619

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    Solute transport in groundwater is significantly influenced by the heterogeneity associated with spatial distribution of the hydraulic conductivity. Understanding solute transport behavior in heterogeneous flow fields is fundamental to develop appropriate models in aquifer management. In this study, laboratory-scale two-dimensional tracer experiments were carried out in a 1 m length, 1 m height and 0.03 m thickness sandbox to quantify solute macrodispersion phenomena in heterogeneous porous formation. Dye tracer of Brilliant Blue FCF mixed with NaCl was applied as a pulse type source and subsequent transport behavior of dye was recorded with digital camera. In addition to the spatial moment approach, temporal moment approach was also applied to estimate the longitudinal macrodispersivity by means of NaCl concentrations at an observation point in the flow field. The experimental results indicated that longitudinal and transverse macrodispersivity were larger than those in homogeneous formation.  Moreover, it was revealed that both macrodispersivities in longitudinal and lateral directions have a non-dependency of the regional flow rates. Laboratory study was extended by the comparison with other studies, indicating adequate results in a suitable quantification range. 

  5. BEHAVIOR OF GEOGRID REINFORCED SAND UNDER VERTICAL LOAD Download Article

    Danny Useche Infante, Gonzalo Aiassa Martinez, Pedro Arrúa and Marcelo Eberhardt
    • Article Type: Research Article
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    • Pages (1862-1868)
    • No of Download = 665

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    In previous works several experimental investigations aimed at establishing the behavior of granular soils reinforced with geosynthetics have been conducted. It has been found that the capacity of the soil improves due to a tensile force given by the geosynthetic that thus provides a soil reinforcement function and therefore allows a better distribution of pressure in the soil. Many of these studies report the use of CBR tests to characterize the behavior of reinforced soil. The CBR test measures the vertical deformation with application of vertical loads, by which it is possible to characterize the stress-strain behavior of the material. In this paper, modified CBR tests are performed on samples of granular soils reinforced with geogrids in order to establish the behavior of reinforced soil at the load application surface from foundations; in this case the displacements are restricted in the cylinder edges of CBR test. The results are compared with those obtained by CBR testing performed without restricting displacements at the edges and without including any type of reinforcement, which were documented in previous work of the authors. 

  6. LOAD-STRAIN-TIME BEHAVOURS OF TWO POLYMER GEOGRIDS AFFECTED BY TEMPERATURE Download Article

    Thitapan Chantachot, Warat Kongkitkul and Fumio Tatsuoka
    • Article Type: Research Article
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    • Pages (1869-1876)
    • No of Download = 785

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    A special series of tensile loading tests was performed on two types of geogrid using a wide variety of load and temperature histories to evaluate the effects of ambient temperature on their load-strain-time behaviours. The applied loading schemes included monotonic loading and sustained loading under different controlled ambient temperature conditions. The followings were found from test results and their analysis performed in this study. With an increase in the ambient temperature, the rupture strength and stiffness decreased while the creep strain increased associated with a decrease in the stiffness. The creep strain by sustained loading during which the temperature was elevated from 30 oC to 50 oC was significantly larger than the one by sustained loading during otherwise monotonic loading at the constant temperature equal to either 30 oC or 50 oC. The elastic stiffness decreased with an increase in the temperature while increased with the tensile load level. Importantly, the residual tensile strength observed at the same ambient temperature was essentially independent of pre-rupture loading histories. 

  7. THE PROPAGATION BEHAVIOR OF PILE-DRIVING-INDUCED VIBRATION DONE ON SOIL AT VARYING DISTANCES AND ITS EFFECTS ON EXISTING STRUCTURES Download Article

    Dungca J.R., Acosta D.Y., Juego M.B., Sanchez H.M. and Sanchez I.S.
    • Article Type: Research Article
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    • Pages (1877-1883)
    • No of Download = 853

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    Pile driving operations are becoming a prevalent practice in Metro Manila due to the presence of soft soil conditions. However, ground vibrations are induced in the process, which could cause possible structural damages to the nearby existing structures. Ground vibration measurements were recorded at three designated sites at 3, 15, and 30 meters away from the pile-driving source through the use of three of Guralp’s accelerometers. A defined attenuation behavior of the emitted vibrations was observed when the pile was in contact with the predominantly sand and silt layers, vibration prediction models for sand and silt layers were formulated and then validated with the measurements obtained at the other two sites, predicted results were correlated to existing vibration limits, a zone of influence was then generated and is capable of identifying the types of structures that are susceptible to structural damage within a radius of the source of pile driving.

  8. VEGETATION RECOVERY PROCESS ON LANDSLIDE STEEP SLOPE AFTER Alnus sieboldiana AND Miscanthus condensatus PLANTING WITH SIMPLE TERRACING WORK IN MIKURA-JIMA ISLAND, JAPAN Download Article

    Tetsuo Okano and Teruo Arase
    • Article Type: Research Article
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    • Pages (1884-1890)
    • No of Download = 675

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    Typhoon 9512 hit the island of Mikura-jima in 1995, causing many landslides and destruction of forest vegetation. For long-term observation of vegetation change, a research plot was established on a landslide slope in 2003. A simple terrace was built on this slope, which was planted with native species (Alnus sieboldiana and Miscanthus condensatus) in 2000 to accelerate vegetation recovery. From 2003 to 2012, a vegetation survey of the plot was conducted to elucidate the vegetation recovery process at an early stage. A. sieboldiana grew steadily and its density of individuals decreased. The number of species gradually increased due to invasion of new seedlings from adjacent forests, i.e. Castanopsis cuspidata, Persea thunbergii. We found some differences in vegetation recovery from another research site, which is a landslide slope seeded with exotic pasture grasses by helicopter in 2002. Seeding of exotic pasture gasses prevented the establishment of trees and reduces successional velocity.

  9. CYCLIC BEHAVIOUR OF JOHOR SAND Download Article

    Aminaton Marto, Choy Soon Tan, Ahmad Mahir Makhtar and Siti Norafida Jusoh
    • Article Type: Research Article
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    • Pages (1891-1898)
    • No of Download = 882

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    Series of laboratory testing on the investigation of soil liquefaction using cyclic triaxial test had been carried out by researchers around the world but many of the results are contradictory. Thus, it is important to first determine the condition in which the clean sand is most susceptible to liquefaction, then only the liquefaction susceptibility of sand matrix soils could be compared and discussed under this specific condition. This paper presents the undrained behaviour of Johor sand and sand mixed with fines (kaolin) from cyclic triaxial tests. Stress controlled triaxial test apparatus was used to shear the isotropically consolidated soil samples under undrained two-way cyclic loading until the initiation of liquefaction. The liquefaction was defined based on: (i) excess pore pressure was equal to effective confining pressure or (ii) double amplitude strain of 5 % was reached, whichever was achieved first. The results of two-way cyclic triaxial tests on clean sand showed that besides the cyclic stress ratio, the liquefaction resistance of the sand under undrained loading was proportional to effective consolidation pressure and density index. The Johor sand was more liquefiable at its loose state and under low effective consolidation pressure, when subjected to earthquake loading.

  10. LESSONS FROM THE INTERNATIONAL COMPARISON OF CONTAMINATED LAND POLICIES WITH RISK GOVERNANCE IN JAPAN, THE NETHERLANDS, AND THE UK Download Article

    Tomoko Miyagawa, Noriko Otsuka and Hirokazu Abe
    • Article Type: Research Article
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    • Pages (1899-1905)
    • No of Download = 679

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    After the Great East Japan Earthquake and Fukushima Daiichi nuclear disaster, decontamination has been undertaken primarily to remediate residential areas.   Therefore, it is necessary to consider risk governance in decontamination process.  This paper aims to examine contaminated land policies by comparing Japan, the Netherlands, and the UK by literature reviews from the aspects of risk governance towards sustainable decontamination process.  The results clarified that policies in Japan is disintegrated and sectionalised by separate acts.  Contrastingly, integrated contaminated land regimes are practiced in the Netherlands and the UK on contaminated risks from current land uses.  In terms of risk governance in contaminated land policies, although the Netherlands has a limited application, Japan and the UK have a certain degree of community participation in recent policies.  Thus, recent contaminated land policy frameworks are adapting to promote risk governance in decontamination process by introducing statutory requirements.    However, there is a limitation to ensure risk governance by statutory actions and more support to voluntary actions is needed.

  11. MICROSTRUCTURE OF SUPERCONDUCTING CABLE COMPONENTS Download Article

    Svetlana Barannikova, Galina Shlyakhova, Lev Zuev and Anatoly Malinovskiy
    • Article Type: Research Article
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    • Pages (1906-1911)
    • No of Download = 607

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     Using atomic force, optical and electron microscopy methods, the changes in the microstructure and phase composition were investigated for the alloy Nb47%Ti used for the manufacture of superconducting cable employed as current-carrying elements in the magnetic system for International Thermonuclear Experimental Reactor. The test samples were prepared from the superconducting wire at an intermediate step of the drawing process for the area reduction Ø1.3→Ø1.2 mm. The effect of cold drawing and intermediate annealing on the properties of as-worked Nb-Ti alloy was assessed. Local strain zones were found to occur in the rupture area. The shape and chemical composition of Nb-Ti wire was examined for both a defect-free area and the rupture area. A Nb diffusion barrier was found to occur in the copper matrix of Nb-Ti wire.

  12. EFFECT OF RICE STRAW LENGTH ON MECHANICAL PROPERTIES OF QUICK LIME AND RICE HUSK ASH STABILIZED SOIL Download Article

    Ayaka Oya, Satoru Iida, Masamitsu Fujimoto, Ryoichi Fukagawa and Der-Her Lee
    • Article Type: Research Article
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    • Pages (1912-1917)
    • No of Download = 881

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    Riverbank collapse often occurs along the Saigon River which flows through Ho Chi Minh City (HCMC). One of the influencing factors is the soft ground which is the riverbank composed of. Our research about the ground improvement method using quicklime, rice husks ash so far. Rice straw is newly added to the improved soil in this paper. The Rice straw is expected to improve the failure strain property that is to restrain brittle failure. These mixing materials can be obtained easily and cheaply in Vietnam. A series of unconfined compression tests are carried out to improve the mechanical properties of improved soil. Moreover pH tests are conducted to validate the chemical action of the improved soil and evaluate the effect of improved soil on surrounding environment.

  13. SOME ASPECTS OF PHYSICAL AND MECHANICAL PROPERTIES OF SAWDUST CONCRETE Download Article

    A.S.M. Abdul Awal, A.A.K. Mariyana and M.Z. Hossain
    • Article Type: Research Article
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    • Pages (1918-1923)
    • No of Download = 2039

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    This paper presents experimental results on some physical and mechanical properties of concrete containing sawdust. Concrete specimens having various cement to sawdust ratios of 1:1, 1:2 and 1:3 by volume were made and tested for workability, density, water absorption, strength and modulus of elasticity at different curing periods of 7, 14 and 28 days. It has been found that with the increase in the amount of sawdust, the workability and density of concrete decreased; the water absorption capacity of concrete, however, increased with the increase in volume. Although the strength of sawdust concrete increased with curing period, the strength and the corresponding modulus of elasticity decreased with the increasing amount of sawdust in the mix. The results obtained and the observation made in the short-term investigation suggests that sawdust concrete can suitably be used as a building material in construction.

  14. OCEAN DECONTAMINATION: REMOVAL EFFICIEMCY OF RADIOACTIVE CESIUM FROM OCEAN SLUDGE BY USING MICRO BUBBLES AND ACTIVATING MICROORGANISMS Download Article

    Kyoichi OKAMOTO and Takeshi TOYAMA
    • Article Type: Research Article
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    • Pages (1924-1928)
    • No of Download = 624

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    The Fukushima nuclear accident of March 11, 2011, soil and water had been contaminated by radioactive cesium. Moreover, radioactive cesium was found in the sludge in Tokyo Bay by flowing from rivers. Here, it cannot be easily removed the cesium which is adsorbed to the sludge. On the other hand, one of the authors had developed the decomposition system for sludge with circulation type by micro-bubbles and activating microorganisms. Here, based on the hypothesis that radioactive cesium is adsorbed on the surface of the sludge. It is considered radioactive cesium can be eluted, after decomposing the deposited sludge by the decomposition system. If the cesium will be eluted to the water, we can fix the cesium by existing technology such as “Zeolite”. In this study, our objects is to check the removal performance of cesium after the decomposition and elution from the sludge and then fix of cesium in the decomposition system. As the results, we obtained the removal efficiency of cesium was 62.7%.

  15. STATISTICAL EVALUATION OF GEOTECHNICAL CORRELATIONS Download Article

    Waled A. Daoud, Kiyonobu Kasama, Naser M. Saleh, Abdelazim M. Negm
    • Article Type: Research Article
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    • Pages (1929-1935)
    • No of Download = 885

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    Geotechnical correlations are widely used because it can provide fast and cost-effective means of parameter estimation using simple tests. Most of the current correlations were derived from data fitting of measurements for specific site conditions and need to be evaluated before used in other sites.  During the correlation development, the deviation of the correlation from the measured values was evaluated using simple statistical measures. A better method of correlation evaluation may reduce the overall deviation of the geotechnical parameter. Amended Theil Inequality Coefficient (ATIC) is proposed as an evaluation tool because it has the advantage that it considers both position and trend conformities between observed and correlated values. To address the efficiency and rationality of ATIC, evaluation of, 92 compression index correlations by ATIC and different statistical measures was carried out. Comparison between the results showed that ATIC is efficient in assessing the best and worst correlations and it can be considered a good tool for correlations evaluation. 

  16. NATURAL VENTILATION EFFECT ON CO2 CONCENTRATIONS IN CLASSROOMS, WAKAYAMA UNIVERSITY, JAPAN Download Article

    Hiroyuki Ii, Kazuki Taguchi, and Masahiro Yamashita
    • Article Type: Research Article
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    • Pages (1936-1942)
    • No of Download = 675

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    Using a portable CO2 sensor, the CO2 concentration in a classroom at Wakayama University was measured and “natural ventilation”, the open door or window effect was evaluated based upon the number of persons, room size, door or window condition and CO2 concentration. Under no ventilation condition in the classroom, increase of CO2 concentration was 2,000 to 4,000 ppm after 90 minutes and CO2 production per person per hour due to respiration was 0.005 to 0.015 m3/hour/person during a lecture. Comparing CO2 concentration under no ventilation condition with under natural ventilation condition, effect of natural ventilation to reduce CO2 concentration per open space size was calculated. The amount of CO2 gas exchanged outside through doors or windows by natural ventilation was in agreement with the amount of CO2 gas produced by respiration in the room when sizes of open doors or windows were 2.3 to 12.8 m2 or ratios of total room volumes per open door or window sizes were 40 to 180 m. 

  17. BEHAVIOR OF PILE GROUP SUBJECTED TO CYCLIC LATERAL LOADING IN CONTAMINATED SOILS Download Article

    Mahdi O. Karkush and Mahmoud S. Abdul Kareem
    • Article Type: Review Article
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    • Pages (1943-1949)
    • No of Download = 736

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    The impact of soil contamination on the behavior of a pile group driven into clayey soils is the subject of this study. A mechanical model had been manufactured to study the behavior of pile group (2×2) subjected to one-way cyclic lateral loading, and embedded in contaminated soils. The tests were performed on a free headed pile group with two ratios of eccentricity to embedded length (e/L) equal to 0.25 and 0.5. The intact soil samples were obtained from Al-Musayib city in the center of Iraq, while the industrial wastewater is a byproduct discharged from Al-Musayib thermal electric power plant, which is located in the same region where the soil samples have been obtained. The intact clayey soil samples were contaminated synthetically with four percentages of (10, 20, 40 and 100) % by weight of distilled water used in the soaking process of soil samples, which continued for 30 days. On the basis of the results of tests, the different percentages of contaminants have nonlinear effects on the lateral load-displacement relation of the pile group. The lateral resistance of pile group decreased with increasing the concentration of contamination in the soil. The lateral bearing capacity of pile group decreased by (4–31)% for e/L equals 0.25 and 0.5, and the ratio of permanent displacement to the total displacement increased by (18–33)% with increasing the percentage of contamination in the soil. The efficiency of the pile group was (81–87)% from one single pile group.

  18. NUMERICAL EXPERIMENT FOR VIRTUAL PLASTER MODEL TESTS SIMULATING BLOCK SHEAR TESTS Download Article

    Tatsuro Nishiyama and Takashi Hasegawa
    • Article Type: Research Article
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    • Pages (1950-1955)
    • No of Download = 485

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    The strength of in-situ rock masses has been estimated by in-situ rock shear tests for a long time.  However, the mechanisms for the appearance of strength in such tests have not been clarified sufficiently.  This paper presents the results of a numerical analysis of virtual plaster model tests used to simulate block shear tests, which are of a kind of in-situ test.  In the authors’ former study, results were obtained for rock shear tests, another kind of in-situ test, along with real plaster model tests and finite element analyses.  In the present study, some cases simulating block shear tests were analyzed.  The appearance and propagation of cracks in the testing process were simulated with enhanced elements, which represented the displacement discontinuity in each element, as in the former analysis.  The results were compared with the former results to investigate the differences between the two conditions.  The shear strength in the two sets of results was found to be generally similar; however, there were some small differences.  The patterns for the appearance and propagation of cracks differed from each other, while some common features also appeared.  The concentration of stress in the two testing processes occurred in different parts of the materials under the two conditions, and this led to differences in both the failure mechanism and the shear strength. 

  19. DEVELOPMENT OF CAPACITANCE DISPLACEMENT MONITORING SYSTEM AND ITS PERFORMANCE TESTS Download Article

    LIN Wenli, Katsutoshi UENO, Ryosuke UZUOKA, Hisashi SUZUKI
    • Article Type: Research Article
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    • Pages (1956-1963)
    • No of Download = 656

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    Geological disasters caused by slope instability frequently result in great loss to human life and property, and real-time and on-line slope monitoring is a most effective method for mastering the deformation dynamics and early warning of landslide disasters. Considering the numerous landslides and high cost of slope monitoring system, three types of capacitance displacement transducer based on the principle of electrostatic capacitance were designed. Basic performance and long-term stability performance of these capacitors were examined, and the impact of temperature behavior on the capacitance measurement circuit was evaluated. The results showed that, comparing with conventional displacement transducers used for slope monitoring, capacitance type transducers can provide sufficient precision, resolution and measurement range, and applying them in slope monitoring could bring obvious advantages, because of its remarkable economic benefit and effectiveness.