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Dublin, Ireland

Galbraith A.P.,Aberdeen Group | Farrell E.R.,Advanced Geotechnics Ltd | Farrell E.R.,Trinity College Dublin | Byrne J.J.,Byrne Looby Partners
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2014

This paper tabulates the results of 175 static load tests carried out in Ireland, and includes bored, continuous flight auger and driven piles in fine-and coarse-grained material, and also piles terminating in rock. These data are used to show that the ultimate pile resistance (defined at 0.1 times the effective pile diameter, D) predicted using Chin’s extrapolation method was within the range 85-100% of the measured resistance when the pile head settlement was greater than 0.05D. The coefficient of variation of the compressive resistance of the ground against a pile, Rc, for a varying number of load tests carried out on a site reduced from 40% where a single test was carried out to 20% where eight tests occurred. This is considered to be a reasonable lower bound to the within-site variation in Rc, and it is recommended that this level of variation be considered for pile design. © ICE Publishing: All rights reserved. Source

Long M.,University College Dublin | Brangan C.,Applied Ground Engineering Consultants AGEC Ltd. | Menkiti C.,Geotechnical Consulting Group | Looby M.,Byrne Looby Partners | Casey P.,Arup
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2012

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 excavationinduced 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. Source

Long M.,University College Dublin | Daynes P.,Leighton Contractors Asia Ltd | Daynes P.,Skanska | Donohue S.,Queens University of Belfast | Looby M.,Byrne Looby Partners
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2012

Practising engineers in the Dublin, Ireland, area have significant experience in dealing with the Boulder Clay which underlies much of the city. However, the 45 m deep buried pre-glacial channel north of the River Liffey is infilled with fluvio-glacial deposits which behave very differently from an engineering point of view. Case history data from eight sites and a detailed examination of the retaining wall behaviour at two of the sites show that retaining wall movements appear to be governed by system stiffness (i.e. a combination of wall stiffness and support configuration). It seems that relatively simple beam-spring type computer programs will provide data for reasonably accurate designs of retaining walls for basements of up to two levels. Input parameters such as K0, Φ′ and soil stiffness need to be carefully specified. Groundwater inflows can be significant but can be dealt with by providing a good cut-off into the underlying glacial till or bedrock and by conventional pumping techniques. Geophysical techniques such as multichannel analysis of surface waves, S/P waves and resistivity can be very useful for the determination of soil properties, such as degree of saturation, density and stiffness, and for material characterisation (i.e. distinguishing the presence of these materials in contrast to the Boulder Clay). Source

O'Leary F.,Arup | O'Leary F.,University College Dublin | Long M.,University College Dublin | Ryan M.,Byrne Looby Partners
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2016

The performance of retaining walls in Dublin Boulder Clay under undrained conditions is relatively well understood. These structures show very modest lateral movements; this is attributed to the inherent strength and stiffness of the boulder clay and the very slow dissipation of excavation-induced pore water suctions. There are few data available on the long-term behaviour of such walls, however, both in Dublin and elsewhere. The economic downturn in Ireland provided a unique opportunity to improve understanding of the long-term behaviour of these types of excavations. Several temporary works retaining walls remained in place for long periods due to work on the projects having been suspended. The paper gives details of several such projects but focuses on the performance of the 14m high secant piled wall with a single row of ground anchors at Heuston South Quarter. It was designed as temporary works but remained in place for about 7 years, with movements increasing to over 50% more than those predicted at design stage. The paper will present a detailed account of the Heuston wall design, construction and performance and the subsequent remedial works, which were carried out to ensure its long-term stability. © ICE Publishing. All rights reserved. Source

Anderson C.,Byrne Looby Partners | Sivakumar V.,Queens University of Belfast | Black J.A.,University of Sheffield
Geotechnique | Year: 2015

The commonly used British Standard constant head triaxial permeability test for testing of fine-grained soils is relatively time consuming. A reduction in the required time for soil permeability testing would provide potential cost savings to the construction industry, particularly in the construction quality assurance of landfill clay liners. The purpose of this paper is to evaluate an alternative approach of measuring permeability of fine-grained soils benefiting from accelerated time scaling for seepage flow when testing specimens in elevated gravity conditions provided by a centrifuge. As part of the investigation, an apparatus was designed and produced to measure water flow through soil samples under conditions of elevated gravitational acceleration using a small desktop laboratory centrifuge. A membrane was used to hydrostatically confine the test sample. A miniature data acquisition system was designed and incorporated in the apparatus to monitor and record changes in head and flow throughout the tests. Under enhanced gravity in the centrifuge, the flow through the sample was under ‘variable head’ conditions as opposed to ‘constant head’ conditions as in the classic constant head permeability tests conducted at 1g. A mathematical model was developed for analysis of Darcy’s coefficient of permeability under conditions of elevated gravitational acceleration and verified using the results obtained. The test data compare well with the results on analogous samples obtained using the classical British Standard constant head permeability tests. © 2015, Thomas Telford Services Ltd. All rights reserved. Source

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