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  1. Dissipation Behavior of Excess Pore Water Pressure in Sand Mat using Dredged Soil Download Article

    M.S LEE and K. ODA
    • Article Type: Research Article
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    • Pages (351-356 )
    • No of Download = 966

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    The design of sand mat should be reviewed by behavior of excess pore pressure which is obtained by combining characteristics of soft ground with the permeability of sand mat. In this paper, in order to investigate the distribution of hydraulic gradient of sand mat, a banking model test was performed using dredged sand as materials of sand mat, and these results were compared by the numerical analysis results utilizing Terzaghi's consolidation equation. As the results, it shows that the pore pressure was influenced by the settlement increasing in the center area of sand mat as the height of embankment increases, and uprising speed of excess pore pressure due to residing water pressure is delayed comparing with the results of numerical analysis. Sand mats should be laid to reduce the increased hydraulic gradient at the central part of the embankment.

  2. An Interpretation of Mechanical Properties of Bentonite as a Non-linear Elastic Material Download Article

    Y. Takayama, S. Tsurumi, A. Iizuka, K. Kawai, S. Ohno
    • Article Type: Research Article
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    • Pages (357-362 )
    • No of Download = 854

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    Bentonite is usually modeled as a geo-material with elasto-plastic isotropic compression/expansion and plastic dilatancy characteristics. In this paper, fundamental considerations of elasto-plastic constitutive modeling for fully saturated bentonite are investigated. According to uniaxial compression test data by Sasakura et al. (2003), where lateral earth pressure was measured, it was found that the hysteresis response between loading and unloading processes does not appear. It suggested that bentonite is an elastic material in which the swelling line corresponds to the normally consolidated line in the ‘e-logp’ relationship. Also, according to triaxial CU test results of bentonite, it was seen the effective mean stress remains almost unchanged during shearing. This implies that bentonite does not have dilatancy characteristics as defined by the critical state theory. Similar interpretation can be derived from the experimental results obtained from a series of triaxial CD tests by Cui et al. (2006).

  3. On Collapse-Settlement Calculations for Heterogeneous Collapsible-Soil Subgrade Download Article

    Moshe Livneh and Noam A. Livneh
    • Article Type: Research Article
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    • Pages (363-368 )
    • No of Download = 1841

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    In a previous paper the authors have dealt with collapse-settlement calculations for embankments based on a homogenous collapsible soil subgrade. For this same subject the present paper represents modifications to the aforementioned collapse-settlement calculations to include in-situ cases of heterogeneous collapsible-soil subgrades. It is well known that collapsible soil deposits exhibit a high potential for collapse deformation under external loading. Evaluation of the collapse potential is, thus, required for settlement calculations relating to the base of embankments placed on a collapsible soil subgrade. The evaluation conducted leads to the conclusion that collapse potential is dependent upon the following parameters: (a) liquid limit, (b) plasticity limit, (c) in-situ dry density, (d) in-situ moisture content, and (e) applied pressure at wetting in the single-oedometer test. Knowledge of these parameters, together with that of the water-penetration depth into the subgrade stratum and the effect of partial saturation on a reduction of the full collapse potential, is shown to enable a calculation of the amount of collapse-settlement in a heterogeneous stratum.

  4. Environmental Accounting on Treatment and Reutilization of Construction Sludges in Geotechnical Engineering Fields Download Article

    Shinya Inazumi, Hiroyasu Ohtsu and Takayuki Isoda
    • Article Type: Research Article
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    • Pages (369-374 )
    • No of Download = 791

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    In Japan, although the recycling of waste has been promoted, there may be various obstacles. In this study, we focus on construction waste, more specifically, construction sludge, which is less advanced in terms of recycling. Processing cost for materials recycled from construction sludge is higher compared to the cost of mining virgin materials. There are some additional difficulties including delays in schedules due to the time required for processing and the balance between supply and demand. Therefore, we quantitatively assess the benefit of recycling by adding the time factor to the evaluation model with consideration for cost and environmental load. As a result, it is shown that the bottlenecks of construction sludge recycling are higher cost than the cost of mining of virgin materials, high heavy metal contents in the construction sludge, and delays in the recycling process.

  5. Single-Step Extraction to Determine Soluble Lead Levels in Soil Download Article

    Masahiko Katoh, Satoshi Masaki and Takeshi Sato
    • Article Type: Research Article
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    • Pages (375-380 )
    • No of Download = 692

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    This study investigated single-step extraction using EDTA to extract the amount of potentially soluble Pb in soil, which would be almost as much as that in the first four Pb fractions of Tessier’s sequential extraction procedure (SEP), with or without the immobilization amendment hydroxyapatite under different extraction conditions such as concentration and extractant pH. The results clearly showed that 0.1M EDTA (pH 7.5) with a soil/extractant ratio of 1:100 can extract almost 90% of the first four Pb fractions of SEP, and EDTA-extracted Pb was positively correlated with the first four Pb fractions even in Pb-immobilized soil. In conclusion, single-step extraction using EDTA was found to be a useful method to evaluate potentially soluble Pb even in Pb-immobilized soils.

  6. Fibrous Ferrocement Composite with PVC-coated Weld Mesh and Bar-chip Polyolefin Fibers Download Article

    P.B. Sakthivel and A. Jagannathan
    • Article Type: Research Article
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    • Pages (381-388 )
    • No of Download = 367

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    This research is on fibrous ferrocement technology which uses a combination of two non-corrosive reinforcing materials in cementitious matrix, namely the PVC-coated steel weld mesh and synthetic barchip (polyolefin) fibers. A low-velocity impact study was conducted on 250 mm square cementitious slabs of 25 mm thick reinforced with PVC-coated weld mesh (III to V layers) and barchip olefin fibers (0.5%-2.5% of volume of specimens). The energy absorbed by the ferrocement slabs reinforced with PVC-coated mesh and barchip fibers was found to be several times more than that of slabs with PVC mesh only.  The impact energy increases with increase in the number of mesh layers, and also with increase in percentage of barchip fibers from 0.5% to 2.5%. The initial and final crack-width reduce on increasing the proportion of polyolefin fibers in cementitious matrices. 

  7. Evaluation of Run-Off Supply Projects in Hamadan Province (Iran) Download Article

    N. Rostam Afshar and M. Abdoli
    • Article Type: Research Article
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    • Pages (389-391 )
    • No of Download = 363

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    Water resources project is for the control or use of water. Where utilization is proposed, the first question is usually how much water is needed .This is probably the most difficult of all the design problems to answer accurately because it involves social and economic aspect as well as engineering. In order to meet the various demands and of water requirements in Hamadan province which is situated in west of Iran, more than 28 projects were defined and studied, but only few of them were adopted. This paper  presents a   criteria based on the ratio of reservoir capacity to volume of earthen dam named as feasibility factor (F) for exact evaluation of different alternatives to assure the designer, so that, to obtain sufficient quantity of water in a form which can be easily and cheaply made fit for various uses.

  8. Monitoring Program for Cement Grouting of Underground Karst Cavities Download Article

    Hasan A. Kamal and Hassan J. Karam
    • Article Type: Research Article
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    • Pages (392-396 )
    • No of Download = 1587

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    A total of eight ground-surface subsidence was detected in a residential suburb.  The subsurface failure cases in the suburb were investigated in detail after their development.  Results of the investigations indicated that the geological profile in this suburb consists of overburden soil which is underlain by limestone bedrock.  It was concluded that raveling of the overburden soil into the underlying Karst cavities was the main cause of ground-surface subsidence development.  Filling the Karst cavities with cementitious grout was chosen as a treatment measure for the cavity problems.  Before and during the grout works for filling the Karst cavities, continuous monitoring of elevations in some selected points at critical locations were considered as essential tool to detect any slight movement or change that may be evaluated and considered a warning for larger movements or cavity and ground-surface subsidence formations.  The continuous monitoring program was based on two major elements; dilapidation survey of selected high risk locations, ground surface movement and the measurement of water levels for determining water fluctuations. Dilapidation was achieved through topographical site surveys including houses, utilities and general surveys along with a set of pictures illustrating important features.  Station points were set all over the site and their elevations were checked regularly.  Regular periodic evaluation of elevations, water-table levels and crack-meter readings were used as tools to evaluate the impact of the grouting works.  Status of existing structures was checked regularly using crack-meters along with water-table levels through available piezometers.  This paper contains description of the conducted dilapidation and topographical survey.  Results of the monitoring program of the grouting works and their impact on the ground-surface subsidence is also presented in this paper.

  9. Assessment of Runoff in the High Humid Foot-hill Areas of Arunachal Himalayas Using Thornthwaite Equation Download Article

    Thornthwaite Equation by Md. Eahya Al Huda and Surendra Singh
    • Article Type: Research Article
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    • Pages (397-401 )
    • No of Download = 712

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    Present study examines daily runoff trend in Dikrong river catchment which is located in the lower foot-hills of Arunachal Himalaya. The river catchment is characterized by the monsoon dominated hydrologic regime. For the purpose daily statistics of temperature, rainfall and discharge were collected from the various sources of state Government of Assam, Guwahati and Government of Arunachal Pradesh, Itanagar and used for testing the validity of Thornthwaite-Mather [T-M] method in Dikrong river catchment of high humid areas of Arunachal Himalayas. It is found that this method is not suitable for the correct assessment of daily Potential Evapotranspiration [PET] as well as daily runoff [RO]. The fluctuation in predicted RO are found more than the observed RO with an over estimation during high rainfall intensity and under estimation in the period of low rainfall regime.

  10. Evaluation and Prediction Method on Neutralization of Supplied Long-term Hydraulic Concrete Structure Download Article

    Man-Kwon Choi, Yuki Hasegawa, Shinsuke Matsumoto, Shushi Sato and Tsuguhiro Nonaka
    • Article Type: Research Article
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    • Pages (402-406 )
    • No of Download = 1032

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    Velocity of neutralization is occupied by three factors; W/C ratio in mixture proportion, type of cement and supplied environmental condition. Hydraulic concrete structures are objective in this study. Influences of supplement condition to neutralization characteristics were evaluated. As a result, coefficient of neutralization velocity of concrete exposed to air is larger than that of concrete exposed to water. However, as for hydraulic concrete structure, mortar is disappeared and coarse aggregate is exposed from concrete surface in water during long-term supplement. It means that coefficient of neutralization velocity of concrete in water could be an apparent coefficient and actual coefficient was almost same with that of concrete in air. On the other hand, coefficient of neutralization velocity of concrete canal was smaller than that of general engineering structures. Furthermore, neutralization depth and velocity of concrete canal was different even in same member. Therefore, it seems reasonable to conclude that evaluation of neutralization should be careful when concrete in water is measured.

  11. Effectiveness of Chloride Salts on the Behaviour of Lime-Stabilised Organic Clay Download Article

    N.Z. Mohd Yunu, D. Wanatowski and L.R. Stace
    • Article Type: Research Article
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    • Pages (407-412 )
    • No of Download = 976

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    The presence of organic matter, in particular humic acid, is one of the most important factors affecting the effectiveness of lime stabilisation of clays. In this paper, an investigation on the effects of humic acid and chloride salts on the strength of lime-stabilised organic clay is presented. Different humic acid contents of 0.5%, 1.5% and 3.0% were mixed with kaolin prior to the stabilisation with 5%, 10% and 15% hydrated lime. The strength of the lime-treated organic clay was analysed using the Unconfined Compression Strength (UCS) tests at different curing periods of 7, 28 and 90 days and further verified by microstructure analysis. The results showed that a significant strength loss was obtained beyond 1.5% humic acid content and the strength was diminished at longer curing periods. However, by adding 0.5% chloride salts, the behaviour of lime-treated specimens with 1.5% humic acid content was successfully improved.

  12. Sliding Stability of Dry Masonry Block Retaining Wall Structure with a Resistance Plate Download Article

    Akihiro Hashimoto, Noriyuki Yasufuku, Yoshio Suematsu, Kazuo Fujita and Toshimitsu Komatsu
    • Article Type: Research Article
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    • Pages (413-418 )
    • No of Download = 989

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    There are two types of block masonry in the structural retaining wall, one is "dry masonry" and the other one is "wet masonry". However, the sliding stability of the dry masonry type retaining wall may be inferior to that in wet masonry block. In this study, a new dry masonry type retaining wall is discussed, which is not only environmental friendly but also structurally stable. A resistance plate is newly attached to the boundary between upper and lower blocks to enhance the sliding resistance, which is due to the passive earth pressure mobilized in the plate. A series of model tests was carried out, paying attention to the position of the resistance plate, mobilized earth pressure in the plate and the horizontal movement of the blocks. It was indicated from the model tests results that the position of the resistance plate becomes very important to effectively increase the block stability.

  13. Experimental Study of Suction-Monitored CBR Test on Sand-Kaolin Clay Mixture Download Article

    Purwana YM Nikraz H and Jitsangiam P.
    • Article Type: Research Article
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    • Pages (419-422 )
    • No of Download = 1256

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    Conventional laboratory CBR test has been widely used for predicting bearing capacity of subgrade layer for pavement design. In unsaturated soil, suction is one of the key parameters for understanding the soil behavior. The analysis of CBR is commonly presented in CBR-water content relation. The information of CBR based on soil suction is very rare and more study is still required. This paper presents a laboratory experiment of CBR test with direct suction measurement. Suction-monitored CBR test is introduced by attaching tensiometers on CBR mold and its surcharge. The standard compacted test on various proportions of sand-kaolin clay mixtures starting from 0% (pure sand), 5%, 10%, and 20% of clay were used. The tests were performed with different value of water content in both soaked and unsoaked conditions. The results indicated that the CBR versus matric suction forms a bi-linear curve. The discussion is presented in term of CBR-water content and CBR-matric suction relation.