With the exception of part of the LBrBC, all the units have been interpreted as lodgement tills. The UBrBC has resulted from oxidation of the clay particles in the top 2–3 m of the UBkBC, resulting in a change in colour from black to brown and a lower strength material. These authors identified four distinct formations of the Dublin Boulder Clay, namely the upper brown boulder clay (UBrBC), the upper black boulder clay (UBkBC), the lower brown boulder clay (LBrBC) and the lower black boulder clay (LBkBC). With the construction of the Dublin Port Tunnel (DPT), a clearer understanding of the detailed geology of these deposits has emerged, see Skipper et al. Issues relating to the design, construction and performance of walls in these two areas are the subject of two separate papers by Long et al. These sites previously would have been considered unsuitable for deep basement construction. This period has also seen the development of marginal sites, for example areas of Dublin docklands, built on recent filling over soft alluvial soils to reclaim land. provide some overall conclusions and recommendations for the design and construction of future similar schemes.Īn exception to the general cover of Dublin Boulder Clay is an area north of the city centre where an old channel of the River Liffey has been infilled with fluvio-glacial sands and gravels.
present an overall summary of the behaviour of retaining walls in Dublin Boulder Clay compared to similar support systems worldwide.17♵ m excavation at the northern cut and cover section of the Dublin Port Tunnel project, which is among the deepest excavations carried out in Dublin to date.7 m cantilever wall excavation at Ballycullen Road where monitoring information for some six years is available#b.7♵ m excavation for relatively highly stressed anchored wall at Trinity College Library#b.lightly supported ‘regular' wall for 6 m excavation at Leinster House where pore water and earth pressure changes were measured in additional to regular monitoring#b.review in detail the general behaviour of walls in Dublin Boulder Clay by reference to four case histories namely:#b.outline the presently used design approach.briefly review the background geology and ground conditions.The purpose of this paper is to provide an overview of aspects relating to the design, construction and behaviour of retaining walls in Dublin Boulder Clay. Valuable full-scale data have been obtained from a good number of these projects. Over the previous 15 years, economic growth in Ireland has led to an increase in the use of underground space, with some developments now including four underground levels.
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