A case study of embankment construction on soft alluvial soils in Limerick, Ireland

A case study of embankment construction on soft alluvial soils in

Limerick, Ireland

Trevor Orr, Trinity College, Dublin, Ireland

Marina Pantazidou, National Technical University of Athens, Greece

Where are we?

North west Europe…

Where are we? – Zoom 1

Ireland…

Where are we? – Zoom 2

West Ireland…

River Shannon

Where are we? – Zoom 3

West of Limerick

River Shannon

The approach to Limerick Tunnel

River Shannon

Highway embankments on soft alluvial soils

Submerged tunnel

Cross section to be studied

View south towards the tunnel

Buggy & Curran (2011)

Continuing south: Killarney & Lakes (Ladies view)

Heading north: Cliffs of Moher

Bypassing Limerick through the tunnel

Buggy & Curran (2011): Figure 1Cross section to be studied

Different earthwork types along highway

Buggy & Curran (2011): Figure 10

ground improvement: vertical drains & surcharge

chainage 0+000

Cross section to be studied at chainage 4+150

Geologic profile in the vicinity of cross section at chainage 4+150

3m glacial till

limestone 4+150 2.9m alluvial clay/silt

topsoil

CPT 517CPT 516

Cross section 4+150

8.75m embankment: required height for motorway

2.75m surcharge

3m soft silt/clayglacial till

& limestone

11m class 2C fill

0.5m drainage layer class 6C fill

25.6m

2

11

1

Drains at a 1.3m center-to-center distance

Simplified cross section 4+150

8.75m embankment

3m soft silt/clayglacial till

26m

2

1

GWL

Undrained shear strength for 4+100 – 4+180 segment

cu=0.3xpo’

design profile

CPT 517

CPT 516