Advanced mini piling systems was contracted to provide piling services for a local Property development company, based in Bath; The site is at the top of Bath over looking the whole city. There are 5 plots on the site, each with a 4-5 bedroom luxury home, 3 of the plots were based on traditional foundations, because they were on the crest of the hill and based into the natural layer of brash (local stone).
The 2 remaining properties are located on the bottom of the site below the crest of the hill, and both have basements in the their designs, so the commencing surface level would be below the layer of Brash and into the fullers earth, which meant that these 2 properties would require piling, because lateral and vertical loads could not be gained via traditional strip footings.
Our engineer choose to use 220mm dia Steel cased bottom driven piles, with a 300mm thick reinforced concrete slab. One of the problems we came across while driving the piles, was that they hit softer layer of stone which made the piles bend off vertical, this happened in every location we tried; So to save the client time and money, and as the access to the site was restricted, the option for a bigger CFA rig was out of the question. The solution we came up with, was to base the piles in the soft stone, which meant they were shallower, and double up all the heavily loaded piles.
Scope of works
*Mobilise D1000H to site.
*All 220mm dia steel cased tube delivered to site in two loads.
*Install all piles to engineers specifications.
*Reinforcement for piles.
*Set up safe location for mobile boom pump.
*Concrete all piles.
The 3.0m firsts plugged up, and ready to be driven in plumb; The D1000H can lift its driving hammer over 3.0m which means the rig can drive, while other casings are being welded together which gives us a higher productivity.
We achieved very close centres to the temporary retaining wall.
All piles concreted with a mobile boom pump and a C35 pump mix.