Now showing 1 - 2 of 2
  • Publication
    Retaining walls in Dublin Boulder Clay, Ireland
    A good number of deep excavations have been recently completed in Dublin Boulder Clay, Ireland. These have included propped walls up to 25 m deep and permanent cantilevers 7.5 m high. Experience elsewhere in the world was used to design and construct these walls. However, case history data have shown that the behaviour of the walls in Dublin Boulder Clay is very rigid and much stiffer than comparable systems worldwide. It appears this behaviour is due to the inherent natural strength and stiffness of the soil and the slow dissipation of excavation induced depressed pore pressures or suctions. There appears to be scope for developing more efficient designs and in particular for reducing propping requirements. For temporary works, the use of undrained parameters in serviceability limit state calculations together with implementation of the observational approach on site could be considered for future schemes.
    Scopus© Citations 19  1220
  • Publication
    The shaft capacity of CFA piles in sand
    (American Society of Civil Engineers, 2009-06) ; ;
    This paper presents the results of a series of field experiments performed to study the development of shaft resistance on Continuous Flight Auger piles installed in sand. The test piles were instrumented in order to separate the shaft and base resistance, and to allow the determination of the distribution of shaft resistance along the pile shaft. The tests highlighted the importance of accurate calculation of the shaft resistance for non-displacement piles. At a typical maximum allowable pile head settlement of 25 mm, more than 71 % of the pile resistance was provided by shaft friction. Conventional methods of estimating shaft resistance were assessed. It was found that methods which incorporated parameters directly interpreted from in-situ test results provided the most consistent estimates. In the final section, differences between the shaft resistances mobilised on displacement and non-displacement piles are considered.
    Scopus© Citations 33  1971