Archive for the Somerset Category
Piled Extension in Frome, Somerset
There were many challenges on this job, the customer required 4 No triangular pads, each designed with 3 No 150mm dia Steel Cased Bottom Driven, Cast In situ Piles, to extend a 3 bedroom house. The extension is to be built between the existing house, and a public footpath, which means the new extension is triangular in shape and built right up to the perimeter fence. The access to site was down the 1.2m wide footpath, where all materials and equipment had to be manoeuvred. Upon further inspection it was found that the main sewer for the houses in the vicinity, was located under the corner of the existing dwelling and travelled down through the proposed extension. Advanced Mini Piling Systems redesigned the pad positions, and contacted the local water authorities, the answer was to move one of the pads, adding an extra pile, and pre boring all the Steel Cased Bottom Driven Piles, past the depth of the main sewer pipe, relieving the pipe of any pressure from the displaced material while the Piles were being driven.
The Piles in this pad were pre bored, beyond the depth of the mains sewer and had anti heave sleeve installed, which is the cardboard tube you can around the base of the Piles. The Piles were then driven to a pre-designed set, concreted with reinforcement, and then cut down to cut off level ( CoL ).
Brent knoll, Somerset
To provide 220 steel cased bottom driven piles to a pre designed set, and fabricate and cast 450 x 350mm R/C beams, for a detached garage, office and utility room. The main property is located on the Somerset levels, and surrounded by land drains which prevent the main river from flooding and carry away excess water from the farm land.
When we started the project the level of the drain was 0.6m below commencing surface level, and all piles were driven to their pre designed set, and were then concreted. After waiting for the piles to cure we then proceeded to excavate for the beams, and because of the heavy rainfall the drain level rose to 0.1m below commencing surface level, which unfortunately was 0.5m above our bottom of dig, so all the beams flooded, and we were unable to continue with work until the water level of the drains fell. We returned a month later once the water level had receded, and completed excavating the ground beams, we used a mobile line pump to concrete the beams as the access to site would not allow larger vehicles onto the driveway.
Scope of works;
*Welfare facilities provided by client.
*Check for services.
*Install 220 Steel cased bottom driven piles.
*Fabricate and install steel reinforced beams.
*Pour beams with C35 concrete.
*Clear site and leave tidier then when we arrived.
Unfortunately the perimeter of the new extension, came parallel to the bank of the land drain which had been built up by the previous owners, so as soon as we disturbed the ground near the bank, it breached the drain flooding the excavated beams. Because of the abnormal weather conditions that had been taking place, the drains were full and we left site until the water level had receded and would could continue with works.
The smaller tie beams which can be seen are 350 x 350mm these will carry very little load; the one furthest away will carry the rear of the garage wall, which is timber, and closest one in the photo will support the the block and beam floor.
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.
3 Bedroom mid terrace house in Weston-Super-Mare,
with subsidence to the front and rear of the property. The house is positioned between a block of 5 flats and another 3 bedroom house, and on removal of the plasterboard inside it was found that the property was built with no cavity on the party wall adjacent to the flats. Both party walls are built off piled beams and the front and rear of property is built off standard footings.
Externally there are major cracks to front and rear of the brickwork and internally the aerated concrete blocks are all loose and cracked on both the first and second floor of the house.
Scope of works:
*Remove reinforced concrete floors and excavated down to bottom of slab before Piling work commences.
*Resin bond all cracks with Heli bar.
*Mobilise T5000 Rotary Bored Auger Rig which will bore 250mm dia to 5.0m reducing vibration and taking us past any obstructions before Driven Piling starts.
*Demobilise T5000 and mobilise D500 Piling Rig to drive 17 No 220 Steel Cased Bottom Driven Cast Insitu Piles.
*Demobilise D500 and concrete all Piles with reinforcement.
*Break out needles in walls front and back.
*Fabricate 250mm reinforced concrete slab.
*Remove jacks for total isolation and clear site.
While removing the reinforced concrete floors we found that the footings at the rear of the house were found to be a lot wider than anticipated and 2 Piles were redesigned and placed outside.
With all 17 No. 220 Steel Cased Bottom Driven Piles, installed to designed depth and concreted, the underside of the reinforced concrete slab is blinded ready for laying out the steel reinforcement. As there is no Heave involved in this job just insufficient footings, we are not using any void forming collapsible materials and no Anti Heave Sleeve around our Piles (Which where there is Heave involved allows the top stratum of clay to move with the changing variables of weather).
The Reinforced steel slab has been fabricated insitu and 500 x 250 needle beams have been inserted into the walls, picking up the front and rear walls and preventing them from sinking by transferring the load through the entire 250mm deep Reinforced concrete slab.
We have a H12 top and bottom mat with H16 bar’s running side by side and top and bottom around all Piles locations. The project is now ready for concreting.
All concreted and job finished.