Articles

  1. EVALUATION OF PLASTICITY-BASED SOIL CONSTITUTIVE MODELS IN SIMULATION OF BRACED EXCAVATION Download Article

    Samuel J. Verghese, Cuong T. Nguyen and Ha H. Bui
    • Article Type: Research Article
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    • Pages (672-677 )
    • No of Download = 1086

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    Numerical modelling continues to play a unique and intrinsic role in the process of geotechnical design. Of greatest concern are soil constitutive models that are employed within finite element software to predict soil behaviour. The objective of this paper is to provide a numerical study of the Mohr-Coulomb and Hardening Soil constitutive models in simulation of a braced excavation. The Taipei National Enterprise Centre (TNEC) basement construction process was well documented and the commercial finite element code, Plaxis, was selected for this numerical comparative study. It was found that the Mohr-Coulomb soil model, a first order approximation, produced an underestimation of the diaphragm wall deflection, whilst the Hardening Soil model provided a good prediction of the observed in-situ diaphragm wall deflections.

  2. ULTIMATE BEARING CAPACITY ANALYSIS OF GROUND AGAINST INCLINED LOAD BY TAKING ACCOUNT OF NONLINEAR PROPERTY OF SHEAR STRENGTH Download Article

    Du N.L., Ohtsuka S., Hoshina T., Isobe K. and Kaneda K
    • Article Type: Research Article
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    • Pages (678-684 )
    • No of Download = 667

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    In the assessment of bearing capacity of footing, the bearing capacity formula proposed by The Architectural Institute of Japan (AIJ) has been widely used in Japan for the design of building foundation. However, this formula is limited to simple conditions like simple footing shape, flat ground and uniform material property. Although the rigid plastic finite element method (RPFEM) can solve this complex problem, it has not taken into account the size effect in assessment of bearing capacity. This study newly develops the RPFEM by introducing the nonlinear shear strength property against the confining stress and proposes the rigid plastic constitutive equation of parabolic yield function, basing on the change in the angle of shear resistance of Toyoura sand. The developed method and the bearing capacity formula (established by empirical approach) provided identical results for various footing sizes showing good estimation for wider range of footing size.

  3. MODIFICATION OF KAOLIN MINERALOGY AND MORPHOLOGY BY HEAT TREATMENT AND POSSIBILITY OF USE IN GEOTECHNICAL ENGINEERING Download Article

    Nurmunira Muhammad, Ideris Zakaria and Abdoullah Namdar
    • Article Type: Research Article
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    • Pages (685-689 )
    • No of Download = 924

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    This paper presents an experimental work on the effect of heat treatment on the mineralogy and morphology of kaolin. Kaolin, which is moderately expansive, was preheated at temperatures ranging from 200oC to 800oC by increment of 200oC and cooled at room temperature before it was mixed with peat. Peat represents a compressible soil and has low bearing value. The main aim of the work is to study the effect of heat treatment on shear strength parameters of peat-kaolin mixture. The mixtures are prepared at different proportions, and at each proportion triaxial samples were prepared and tested in the undrained condition to study the shear strength parameters. Untreated kaolin-soil mix was also prepared to provide a comparison between the treated and untreated soil mix in terms of the shear strength behaviour. XRD and FESEM were also carried out to investigate the change in soil micro-structure due to heat treatment. The tests showed that there was a slight improvement in the strength of peat-kaolin mixture when kaolin was preheated to a temperature of up to 400oC. Finally results were discussed and conclusions were made for the preheated kaolin-peat mixture.

  4. CATEGORISING GEOTECHNICAL PROPERTIES OF SURFERS PARADISE SOIL USING GEOGRAPHIC INFORMATION SYSTEM (GIS) Download Article

    Haider Al-Ani, Leila Eslami-Andargoli, Erwin Oh and Gary Chai
    • Article Type: Research Article
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    • Pages (690-695 )
    • No of Download = 703

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    Peat is a highly organic and compressible soil. Surfers Paradise (as a study area) has problematic peat layer which has different thickness at different locations between R.L. -10 to -19.6 m below the ground surface. Buildings in Surfers Paradise are using piled foundations to avoid the high compressibility and low shear strength peat layer. In this paper, geotechnical borelogs are compiled from 51 soil investigation reports in the study area. These borelogs data are then imported into ArcGIS10 as digital layers and converted into assessable formats by Geographic Information System (GIS). This technique has been utilised to produce digital zonation maps for the study area. The application of interpolation techniques allows the production of zonation maps and bring together years of geotechnical data. Standard Penetration Test (SPT) N values have been selected to determine the soil stiffness in the study area. These SPT-N values are then categorised to produce different zonation maps. The occurrence of peat layers can be located using these zonation maps. These GIS-based zonation maps will provide a better overview of subsurface geology, bed rock elevations, and geotechnical properties of the various soil types found in the study area.

  5. SHALE FAILURE AND CRACKING IN A SEMI-ARID AREA Download Article

    Muawia Dafalla, Mutaz, E. , Mansour Al humimidi, Loni Allafouza Oumar and Mosleh Al Shamrani
    • Article Type: Research Article
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    • Pages (696-699 )
    • No of Download = 715

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    A semi-arid shale formation in the northern and central part of Saudi Arabia showed frequent near surface cracks and distress at several sites. This phenomenon was found to be of a serious risk to structures founded on or near cracks or failure zones. This study was carried out for an area where several centimeters wide ground cracks extending over more than one kilometer distance across a populated area in Saudi Arabia. The dominant subsurface formation in the area is reddish brown stiff to hard silty to clayey shale underlain by sandstone formation. The subsurface material was explored and clayey shale samples were extracted. The study included borehole drilling and test pit excavations. Soil classification and consistency tests were performed. A series of physical and chemical testing confirmed the expansive nature of the shale.  The possible causes of cracks and the mechanisms of failure in semi-arid shale were covered and discussed in sufficient details. Engineering guides for buildings and construction in typical zones were presented. 

  6. PREDICTING SETTLEMENT OF CHEMICALLY STABILISED LANDFILLS Download Article

    Behnam Fatahi and Hadi Khabbaz
    • Article Type: Research Article
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    • Pages (700-705)
    • No of Download = 945

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    This paper presents the findings of numerical analyses to predict the vertical and horizontal displacements of closed landfills under surcharge load with and without treatment by chemical admixtures. The finite element program, PLAXIS, has been used to evaluate the settlement of a landfill model. The soft soil creep model is used for this analysis. Five layers of solid waste are considered for the landfill to evaluate the effect of depth of stabilisation on settlement of landfill model. Treated and untreated municipal solid waste (MSW) parameters are obtained from the results of an extensive laboratory program performed on MSW samples in this research. The settlement of the landfill model 10 and 20 years after applying the surcharge load for different fly ash-quicklime contents and various depths of improvement is estimated. Results indicate that treatment of MSW reduces the vertical displacement of the landfill model under surcharge load significantly. This reduction is more with higher depths of improvement. The finite element results have been validated based on results of triaxial tests conducted in the laboratory on the treated municipal solid waste.

  7. ENVIRONMENTAL CONDITION INDEX FOR ESTIMATION ON EUTROPHIC STATE OF ENCLOSED AQUIFER ECOSYSTEM Download Article

    Kazuhito Murakami, Michio Gomyo, Saki Agatsuma, Yoshimasa Amano and Akiko Inoue-Kohama
    • Article Type: Research Article
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    • Pages (706-711 )
    • No of Download = 694

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    To evaluate the effect of sediment treatment on aquifer ecosystem, a new ecological index that is composed of water quality, sediment quality and biota quantity was proposed in this study. According to ECI (Environmental Condition Index), DAF treatment (Dissolved Air Flotation) + MgO sprinkling was assessed as the most efficiency method for improvement of eutrophicated ecosystem, that is, this method can make the organic matter quantity in aquatic ecosystem minimum level in comparison with other sediment treatment method. Also, for application of this method to real field remediation such as eutrophicated lake, marsh, reservoir and so on, more detailed analysis for treatment function and optimum condition of sediment treatment was considered to be necessary.

  8. FLOW PATTERN FOR MULTI-SIZE SILOS Download Article

    Yi Yang, Na Li, Peng Yin and Y.M. Cheng
    • Article Type: Research Article
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    • Pages (712-716 )
    • No of Download = 919

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    Silo container is a very important storage structure for coal, sand and other granular materials. Nonhomogeneous granular flow is sometimes found in ore discharging in mining engineering, but so far there are only limited studies to this topic, particularly for double opening silo. In views of that, it is necessary to figure out the details about the flow pattern behavior. In the present paper, four physical models are designed to investigate the flow patterns for silos discharge behavior with double openings. The opening spacing, height ratio, sand properties and automatic separated manners are considered in these laboratory tests. Meanwhile, two-dimensional discrete element method is used to reproduce the flow behavior as well as to evaluate the dynamic wall stresses distribution on the silo hopper from bottom to top. It is found that the flow pattern is very sensitive to the spacing between openings under close opening silos. For the wide opening silos, the discharge efficiency would change nearly 30%. The arch effect in the dead zone and ore recovery are significantly influenced by the height /spacing ratio. The results from discrete element analysis can match well with the experimental study if suitable micro-parameters are used in the analysis.

  9. CHARACTERISTICS OF SLOPE FAILURES IN MAKINOHARA, JAPAN Download Article

    Jun Sugawara
    • Article Type: Research Article
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    • Pages (717-722 )
    • No of Download = 732

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    Makinohara City, located in south-central Shizuoka Prefecture in Japan, is renowned for the production of high quality Japanese green tea. Approximately 25% of Makinohara City’s land is used as tea plantation fields and annually 5,800 tonnes of tea is produced. However, slopes in this region are occasionally subject to failures following construction activities. In this light, this paper investigates characteristics of slope failures in Makinohara region. Based on the author’s experience, a number of recommendations are also made for slope analysis and mitigation works.

  10. SIMULATING THE EFFECT OF FLOW VOLUME ON SCOURING PROCESS AROUND BREAKWATER UNDER TSUNAMI CONDITION BY SPH METHOD Download Article

    M.R. Islam, K. Hayano and A.M.K.N. Nadeesha
    • Article Type: Research Article
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    • Pages (723-728 )
    • No of Download = 540

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    The study has attempted to simulate scouring process around the breakwater by smoothed particle hydrodynamics (SPH) method. SPH is a mesh less numerical method with a high capability of simulating large deformation of geo-material. However, SPH application in geotechnical problem is relatively new. The study has developed a simplified model arrangement with water and soil particle. Scouring process was simulated for saturated and dry soil by allowing water to fall continuously. The soil has the properties of elastic-perfectly plastic model with Mohr-Coulomb failure criteria. The water has the properties of viscous fluid. Scouring occurred as seepage force tried to drag the soil particles. Scouring process was found to advance with time and with increase in flow volume for both saturated and dry soil. The outcome of the study will help to predict the scour process around breakwater.

  11. STUDY ON GROWTH OF VETIVER GRASS IN TROPICAL REGION FOR SLOPE PROTECTION Download Article

    Mohammad Shariful Islam, B. A. M. Shahriar and Hossain Md. Shahin
    • Article Type: Research Article
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    • Pages (729-734 )
    • No of Download = 748

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    River bank erosion and embankment failures happen continuously throughout Bangladesh. From a strictly economic point of view, the cost of remediating these problems is high, and the state budget for such works is never sufficient. This confines rigid structural protection measures to the most acute sections. General reasons of embankment failure are erosion due to rain splash, wave action, overtopping of storm surge. Faulty design, poor maintenance and poor construction also cause failure. The use of cement concrete blocks, stone revetments, geo-bags, and plantation etc. are commonly used for protection of embankment in traditional practices. These materials are expensive and sometimes are not effective to protect the embankments and river bank for an expected design life. On the other hand, slope stability can be augmented by using bio-engineering techniques. Vetiver grass (Vetiveria zizanioides) is being used as an efficient bio-technology for slope protection in many countries, for its special attributes like longer life, strong and long finely structured root system and high tolerance of extreme climatic condition. A few steps have only been taken recently to employ this technique for slope protection purposes in Bangladesh. This paper presents three case studies of vetiver plantation in slope protection against rain-cut and wind-induced erosion. It is found that vetiver grass grows in different soil and climatic conditions of Bangladesh and it is effective for slope protection. Prospect of vetiver plantation in protecting haor low-land is also discussed.

  12. INTEGRATED ENVIRONMENTAL MANAGEMENT FOR SUSTAINED DEVELOPMENT Download Article

    J. Rajaraman and K. Thiruvenkatasamy
    • Article Type: Research Article
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    • Pages (735-742)
    • No of Download = 371

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    Lowland problems are many. Many urban settlements are on the coastal belt, worldwide. In the past, many urban areas grew in an uncontrolled manner. The urban populations experienced increased risks, a poorer quality of life, and health problems. However, in general, there has been increasing management of many urban environments through Land use planning, building, environmental, health and safety regulations and management of emergencies, collectively balancing social, economic and environmental requirements. In this paper the complexities of urban cities are illustrated through many examples without naming any particular city. Since in modern times, globalization has created an environment where economic borders only exist. The systems are usually administered by separate authorities, which need to act together to secure sustainable urban management. Therefore actions and responses are frequently disconnected and are sometimes conflicting. To attain sustainable growth common sources of information are necessary. To emphasize the following eleven illustrative examples of some urban cities and their issues are discussed.

  13. IDENTIFYING SOLUTE DISPERSIVITY IN UNSATURATED POROUS MEDIA USING A NON-INTRUSIVE TECHNIQUE Download Article

    Kazuya Inoue, Takayuki Fujiwara and Tsutomu Tanaka
    • Article Type: Research Article
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    • Pages (743-748 )
    • No of Download = 722

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    A non-intrusive methodology using spatial moment analysis linked with image processing of a dye tracer behavior in porous media was applied to identify time-series variation of dispersivities not only in longitudinal but in transverse directions under saturated and unsaturated conditions. Dye tracer experiments were carried out in a two-dimensional and vertically placed water tank with the dimensions of 100 cm width, 100 cm height and 3 cm thickness under saturated and unsaturated flow conditions. An image processing technique based on digitalized spatial distributions of dye tracer allowed to link with a spatial moment approach to identify the temporal change of the longitudinal and transverse dispersivities. Dispersivities exhibited an increasing and decreasing tendency associated with infiltration rates and showed a marked difference between estimates under saturated and unsaturated conditions. Transverse dispersivities under unsaturated conditions were approximately one order larger than those under saturated conditions. This attributed to the effect of air distributions in porous media on the temporal and spatial change of solute dispersion phenomena.