Articles

  1. BEARING CAPACITY AND SETTLEMENT OF FOOTINGS IN UNSATURATED SAND Download Article

    Sai K. Vanapalli and Fathi M. O. Mohamed
    • Article Type: Research Article
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    • Pages (595-604 )
    • No of Download = 1517

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    The focus of the study in this paper is directed towards understanding the influence of three parameters; namely, (i) matric suction, (ii) overburden stress, and (iii) dilation, on the bearing capacity and settlement behavior of surface and embedded model footings in unsaturated sands. The results show that the bearing capacity and settlement behavior of unsaturated sands are significantly influenced by all the three parameters. In addition, comparisons are provided between the predicted and measured bearing capacity and estimated and measured settlement values using the proposed modified Terzaghi’s equation and modified Schmertmann’s CPT-based method, respectively. There is a good comparison between the predicted/estimated and measured bearing capacity and settlement values for the laboratory and field tests using the proposed modified methods.

  2. A CONVENIENT MULTI-PARAMETER WATER QUALITY ANALYSIS BY ONSITE FILTERED SAMPLE FOR EUTROPHICATION MONITORING Download Article

    Akira Kikuchi, Nor Eman Ismail, Narges Janalizadeh, Musa Mutah and Muhamad Faiz
    • Article Type: Research Article
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    • Pages (605-609 )
    • No of Download = 605

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    Ion Chromatography and Flow Injection Analysis systems were integrated by a switching valve. Then, sampling kit was designed by disposable syringe, 0.45um syringe filter, and 2mL plastic vial. 13 water samples were collected from oxidation pond and natural stream in a University campus. Four analytical modes were applied for standard solutions and the environmental samples. The detection limit (S/N =3) in µM/L were as follows, SO42- (0.31), Cl- (0.50), NO3- (0.89), Na+ (0.52), NH4+ (0.94), K+ (1.24), Mg2+ (0.76), Ca2+ (1.75), NO2- (0.02), and PO43- (0.12), and its EC was 0.03 µS/cm. Our analytical approach was simple, rapid, low-cost, and multi-parameter that was satisfactory to assess the water samples. Due to the sampling, transportation, storage processes are drastically improved, our approach has potential to contribute to strategic environmental assessment.

  3. CHARACTERISTICS OF EMBEDDED PEAT IN COASTAL ENVIRONMENTS Download Article

    Haider Al-Ani, Erwin Oh and Gary Chai
    • Article Type: Research Article
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    • Pages (610-619 )
    • No of Download = 874

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    This study examines the engineering characteristics and properties of peat soils in coastal environments in Ireland, Italy, Malaysia, Netherlands, Turkey and USA. The engineering properties to be examined are consolidation characteristics, Atterberg limits, density, organic content, shear strength, and moisture content. Moisture content and organic content are good indication of the occurrence of peat soils because these parameters are inherently high in this soil type. In addition, peat soil is highly compressible and is known to be problematic for geotechnical construction. The peat layer has an adverse effect on the long-term settlement of road embankments. A case study of peat soil deposits in Surfers Paradise in Australia will be presented in the paper. Peat soil in the study area is embedded at depth ranging between R.L. -10 to R.L. -19.6 m below the ground surface and it has a thickness ranging from 0.1 to 7.0 m in some locations. It possesses low shear strength of between 30-40 kPa and the moisture content can be up to 247 %. Four empirical equations have been established for the peat soils and they are compared with those published in the literatures.

  4. COLLAPSIBILITY IN CALCAREOUS CLAYEY LOESS: A FACTOR OF STRESS-HYDRAULIC HISTORY Download Article

    Arya Assadi Langroudi and Ian Jefferson
    • Article Type: Research Article
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    • Pages (620-627 )
    • No of Download = 834

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    The re-use of excavated loess in embankments needs a good understanding of its long-term mechanical response. Among the many collapse controlling factors, stress and hydraulic history are of significant importance as certain combination of these can alter the packing state to great extents. However, published works on stress path-packing state interaction is limited to clayey silts, underreporting the contribution of carbonates. Works on hydraulic path-packing state interaction lacks physical evidences for pore distribution, leading to disputes over the variation of air-volume over time and therefore fills’ long-term behaviour. Identical artificial loess specimens were incrementally stressed on dry-, wet-, and wetting-surfaces, while microfabric, suction, particle and pore size distribution were recorded. The response of test material (moderately calcareous lightly clayey silt) showed the failure of dry-compaction in restricting the coefficient of consolidation. Wetting at any stress level improved the pore volumes and thus post-drying collapsibility. However, pre-loading to 25kPa before flooding provided the maximum degree of densification. Water-retention properties were deemed reproducible upon wetting-drying seasons for minimum content of 5-20µm size loess constituents. In short, controlled stress-hydraulic paths can guarantee the long-term response of site-won loess embankments.

  5. IMPACT OF FLOOD DISTURBANCE EVALUATION ON THE STRUCTURES OF GROUND-BEETLE ASSEMBLAGE AT BIOTOPES Download Article

    Michiko Masuda, Rina Sakakibara, Nao Sugimura and Fumitake Nishimura
    • Article Type: Research Article
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    • Pages (628-633 )
    • No of Download = 815

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    In September 2011, the flood of the Shonai and Yada Rivers in the center of Japan brought lots of earth and sand into their biotopes and caused serious damage to their vegetation. Comparing our data of their ground-beetle assemblage in 2010, we could assess the impact of the flood disturbance. After the spring of 2012, when the damage to the assemblage and vegetation was found to be serious, the number of insects gradually increased as the vegetation recovered, and recovered to the original state by the end of the summer. However, the structure of the fauna was very different from the original. The recoverability of the ground beetle fauna was different in each river; the structures of ground-beetle fauna in the Shonai wetland and Yada grassland recovered soon, but those of floodplain forests in both rivers, which were controlled by people, remained the damage till the end of the autumn. Among these, the structure of fauna in the Shonai grassland was nearly at the level of urbanized areas. Since the number of insects increased along with the recovery of vegetation, we believe the recovery of river vegetation is important. Furthermore, in preparation for the possible disasters, we suggest to extend the non-mowing areas for the recovery of insect fauna.

  6. A STUDY OF THE FORMATION MECHANISM OF BEACHROCK IN OKINAWA, JAPAN: TOWARD MAKING ARTIFICIAL ROCK Download Article

    Takashi Danjo and Satoru Kawasaki
    • Article Type: Research Article
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    • Pages (634-639)
    • No of Download = 994

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    Beachrock is coastal sediment that has been cemented mainly by calcium carbonate within the intertidal zone in tropical and subtropical regions. Man-made beachrock has the potential to inhibit coastal erosion. Considering this important application, we performed field investigations and laboratory tests to understand the formation mechanism of beachrock in Nago, Okinawa, Japan. We performed a needle penetration test, microbial population count and urease activity test, and conducted elemental and mineral analyses of the beachrock and sand. Some microorganisms at the site showed urease activity and the beachrock cement comprised high Mg calcite (HMC). Our investigation showed that evaporation of seawater and/or urease activity of bacteria may have resulted in precipitation of HMC, leading to formation of the beachrock, with partial solidification of some sandy specimens.

  7. THE INFLUENCE OF CHLORIDE SALTS ON COMPRESSIBILITY BEHAVIOUR OF LIME-TREATED ORGANIC CLAY Download Article

    N.Z. Mohd Yunus, D. Wanatowski and L.R. Stace
    • Article Type: Research Article
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    • Pages (640-646 )
    • No of Download = 839

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    Previous studies have shown that the compressibility behaviour of lime-treated organic clay with varying humic acid contents were not effective as time prolonged. Therefore, chloride salts in the amounts of 0.5%, 2.0% and 5.0% were introduced in conjunction with lime-treated organic containing 1.5% humic acid content to assess the influence of salts on the improvement of compressibility behaviour of lime-treated organic clay. The compressibility behaviour of lime-treated organic clay with varying amounts of chloride salts was studied at different curing periods. The influence of the chloride salts on the lime-clay reactions was analysed in terms of changes in void ratio (e), volumetric strain (ε1), compression index (Cc), and coefficient of consolidation (cv) which defines a soil’s compressibility. The addition of chloride salts to the lime-treated organic clay shows less compressible behaviour in the long term as evidenced by the oedometer tests. The results confirm the effectiveness of salt in lime-treated organic clay.

  8. TWO-DIMENSIONAL NUMERICAL MODELLING OF MODULAR-BLOCK SOIL RETAINING WALLS COLLAPSE USING MESHFREE METHOD Download Article

    C.T. Nguyen, Ha H. Bui, and R. Fukagawa
    • Article Type: Research Article
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    • Pages (647-652 )
    • No of Download = 1156

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    Box-shape retaining wall system has been extensively used to stabilize natural and cut-slope. Despite this fact, numerical development for prediction of the large deformation and flexible behavior of retaining wall bocks is still not advanced. To overcome this limitation, this paper presents a new numerical approach which can be used to simulate large deformation and flexible behavior of the box-shape retaining wall system. Herein, soil is modelled using an elasto-plastic constitutive model, while wall blocks are assumed rigidity with full degree of motion. A linear contact model is proposed to simulate interaction between soil and wall block. Experiments were also conducted to validate the proposed numerical framework. It is showed that the proposed numerical framework can simulate well behavior of the box-shape retaining wall system. The proposed method can be readily extended to analyze dynamic response of a general segmental retaining wall.

  9. LOWLAND ENVIRONMENTAL GEOTECHNOLOGY OF SEISMOSEDIMENTS OF KANDLA PORT IN INDIA Download Article

    J.Rajaraman and K.Thiruvekatasamy
    • Article Type: Research Article
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    • Pages (653-659 )
    • No of Download = 665

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    The Gujarat coast in India is vulnerable to various natural disasters such as earthquakes, cyclones, tsunamis and agricultural droughts. The nearby main town on main land is Gandhidham.Kandla is located at a distance of about 4 km from Gandhidham. A 20 m wide road connects Gandhidham and Kandla. Geographically, Kandla could not be considered as a port because, there is water on almost 340 0 of this port. Kandla is almost an island. There is only one escape route via the bridge. In case the bridge gets damaged due to natural disasters, then there is no alternate route for rescue, evacuation and escape. At present huge amount of dredging is regularly being undertaken at the Kandla port. On an average about half million cubic meters of dredged materials is excavated, carried and is dumped in deep Sea. In this paper, an integrated approach to the clay behavior (including seismosediments) is considered mainly to relate cohesion and friction under different environmental conditions in lowlands, to shear strength by different types of clay.

  10. SEISMIC SLOPE FAILURE MODELLING USING THE MESH-FREE SPH METHOD Download Article

    N. Hiraoka, A. Oya Ha H. Bui, P. Rajeev and R. Fukagawa
    • Article Type: Research Article
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    • Pages (660-665 )
    • No of Download = 993

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    In the past few decades, majority of dynamic behavior of slope have been conducted using the finite element method (FEM). However, earthquakes often cause large deformation and post-seismic soil deformation which are difficult to predict using the FEM due to mesh distortion issues. As an alternative numerical method, the smoothed particle hydrodynamics (SPH) has been recently applied to geotechnical field and showed to be a promising numerical technique to handle large deformation and post-failure behavior of geomaterials.  In this paper, taking into consideration of this advantage, the SPH method is applied to simulate response of a slope subjected to seismic loading. Reliability of SPH results was assessed by comparing with experimental data available in the literature. It is shown that the SPH method could qualitatively predict slope failure behavior observed in the experiment.

  11. SPATIAL DISTRIBUTION CHARACTERISTICS OF SUBTERRANEAN HOT WATER EVALUATED USING WATER QUALITY CONCENTRATION DATA Download Article

    Takamitsu Kajisa, Si Senfi, Yasunori Mori, Homayoon Ganji, Abdul Saboor Rahmany, Masaaki Kondo and Hajime Narioka
    • Article Type: Research Article
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    • Pages (666-671 )
    • No of Download = 791

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    Spatial distribution characteristics of subterranean hot water were indexed using correlation coefficient's (R) p-values for hot spring water quality indicators. For example, in a case where the p-value of R was smaller than 5%, the correlations of a set of water qualities for two hot springs were significant. In this study, in a dense hot spring area, the minimum distance with a p-value greater than Pc (critical p-value) was proposed as a stochastic and critical distance (Xc) for both new and existing hot spring owners. By using data from 10 hot springs in each area, 45 sets of distances and p-values were examined. Of the five areas examined, three and four Xcs more than 1,000m were found for Pc 1% and Pc 5%, respectively. The experimental relation between the given Xc and the hot spring depth could not be confirmed. Results indicate that the influence of water quality from new hot springs located outside of the Xc range is not always insignificant, even though the water quality of the new hot springs should primarily influence existing springs located within the Xc range.