Close Proximity Piling
DAWSON-WAM was contracted by Duggan Brothers to construct a new basement secant wall to transform a former theatre into an 8 storey hotel. The project was in the heart of Dublin, which meant space was restricted and work was in close proximity to other buildings.
During the construction of the guidewall archways were uncovered that once formed the stage in the old theatre. These ran adjacent to our guidewall over the full length of the East Elevation of the site. The North and West elevation of the site consisted of a busy through road. This proved challenging due to the restricted access to site for large vehicles and the close proximity of the piling rig to the road. To the South of the site there was an existing building consisting of a music shop and restaurants so it was important that our piling work did not affect their business. Vibration monitoring points were set up around the site perimeter which would send an alert if vibrations were outside the workable limit set in advance of the works and all deliveries were planned in advance.
The new development consisted of varying pile diameters so that the client could maximise space available for the hotel basement. In all over 88lm of 630mm, 525mm and 450mm diameter secant walls were installed with piles ranging in length up to 9.5m. At some points during this time the rig was drilling 5m into the very hard Dublin limestone. Hard/Hard secant walls were installed using DAWSON-WAM’s Cased CFA System mounted on an ABI TM18/22 piling rig and were installed extremely close to adjacent structures. Reinforcement was pushed down to cut off level to assist the following trades in breaking down the piles. All piles were integrity tested and a static load test was completed and performed extremely well.
Ground conditions were very challenging and rock was constantly present at 3.5m below pile platform level. From this point certain piles still had 4 or 5m to go to achieve their pile toe level. An archeologist was also on site each week due to the historical nature of the site. There were many houses in this area 200-300 years ago and the archeologist was looking for any signs of this from our borehole spoil.
All the works were completed in very tight site conditions, working in close proximity to many businesses meant that logistics were key so as not to disturb others. With this in mind the Rig movement were scheduled for outside of the site working hours, it was moved in at 5am and out at midnight, to minimise any disruption caused to others. The Rig has to be tracked out onto the main road, as it was impossible to get a low loader on site due to the narrow lane it was on. DAWSON WAM had to liaise with Dublin City Council for permission for this and it was agreed that the rig would complete all of its movement off site using track mats to protect the road.