3 results for Abuel-Naga, HM

  • Simple Method for Correcting Dynamic Cone Penetration Test Results for Rod Friction

    Abuel-Naga, HM; Holtrigter, M; Pender, Michael (2011)

    Journal article
    The University of Auckland Library

    This letter presents a simple method for evaluating the effect of rod skin friction on dynamic cone penetration test results in cohesive soils. The proposed method is simple and requires neither additional equipment nor special test procedures, and thus represents an improvement on existing dynamic probing practice. In a field trial, the proposed approach was shown to work well when compared with the results of a special dynamic cone test where a casing was used to reduce the effect of rod skin friction. However, more field tests at different ground conditions are required to fully confirm the validity of the proposed approach.

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  • Effects of temperature and thermal gradient on thermocouple psychrometer measurements

    Abuel-Naga, HM; Bouazza, A (2011-02)

    Journal article
    The University of Auckland Library

    This paper presents the results of a study aimed at assessing the effects of temperature and thermal gradient on psychrometer readings, and at developing a calibration protocol that takes into account these effects. An intensive calibration programme was conducted at different temperatures (20-35 degrees C) and water potential levels (0.0 to similar to 7.0 MPa), for this purpose. The thermal gradient was expressed as the difference in temperature between wet and dry junctions in the thermocouple psychrometer sensor. The collected calibration data were used to build an artificial neural network psychrometer model. The developed model was able to simulate successfully the psychrometer output at different conditions, and was used to conduct a detailed parametric study to evaluate the influence of temperature and thermal gradient on thermocouple psychrometer measurements. The outcome of this study shows the importance of including the effects of temperature and thermal gradient in the standard calibration process. Moreover, it introduces a new, precise calibration protocol that takes advantage of the artificial neural network approach.

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  • Design curves of prefabricated vertical drains including smear and transition zones effects

    Abuel-Naga, HM; Pender, MJ; Bergado,DT (2011)

    Journal article
    The University of Auckland Library

    The Hansbo theory considers the effect on the consolidation rate of Prefabricated Vertical Drains (PVDs) spacing, and the smear zone induced by PVDs installation process. However, it does not consider the effect of the transition zone between the smear zone and the undisturbed soil. In this paper the standard Hansbo radial consolidation theory has been modified and used as a basis for developing an improved design method for PVDs where the effect of a transition zone with hydraulic conductivity varying linearly with radius is included. The validity of the modified Hansbo theory was checked by comparing its results against those from finite element modelling; very good agreement was obtained. Based on the modified theory, a new simple PVD design chart was developed for situations where the PVD well resistance effect can be neglected (the usual case). The proposed design chart has the advantage of avoiding interpolation since the basic equations are very simple.

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