Archive for the Basements Category
Camden Town Piled Basement London
Advanced Mini Piling Systems, was contracted to install 3o number 450mm dia Hollow Stem Contiguous Piles, for a basement in Camden Town, London. Access was restricted as the site was at the rear of a 6 storey London town house but once on the site, room was of abundance. The Rig used to install the 450mm dia Hollow stem piles was a Klemm KR 702-2, with a silent power pack and safety cage fitted to the rig, with an operating height of 2.5m – 3.5m and a width of 1.8m, the 702-2 can also be used 25m away from its hydraulic power supply. Two parking spaces were allocated for a concrete pump and wash out area, concrete was delivered to site twice a day on a 6.0m3 lorry, and all other materials were stored at the rear of the property.
The Contiguous piles are being used to extend the existing basement which is not lived in but used for storage, and is due to be converted to a luxury flat, the Contiguous Piled Retaining Wall is situated parallel to the rear of the building allowing room for a court yard and a fire escape. This complies with building and fire regulations granting the conversion of an unused space.
Klemm KR 702-2 being hiabed off lorry.
Klemm 702-2 installing 450mm dia Hollow stem piles, a winch is fitted to lift heavy flights on to auger rig. Although a large machine, close proximity of the building is maintained, allowing us to work down the centre line of the Piled Retaining wall.
Once the safety cage is opened the Rig is isolated and spoil can be removed safely by an operative.
Piles cages fabricated on site, with 75mm spacers.
Piled Basement in Banbury, Oxfordshire
To provide 81 number 300mm dia hollow stem piles to 9.0m to form a Contiguous Piled Retaining Wall, allowing for the patio area to be enlarged, by excavating the bank at the rear of the house. The Contiguous Piled wall also forms the steps to lead from the drive down to the patio. The bank is made up of clay, with layers of ironstone, and in most areas is very soft with running water, which is why the chosen piling system is Hollow stem.
The Hollow stem Piles were grouted (a concrete substance made up of sharp sand and cement at a very strong ratio) onsite with a pump and batched by hand. The cages were pre fabricated and consisted of two sections to gain 9.0m, which are bolted together using high strength wire rope clips, which are then plunged through the newly formed pile that has been grouted as the augers have been removed.
Photo of drawing, with the black dots showing the Contiguous Piles, forming the retaining walls and steps.
Pile positions clearly set out and numbered, by client ready to commence piling.
The PPS Unwin Kitten rig being used with 300mm dia Hollow stem flights, a very powerful yet compact Piling Rig, with grout hose to rotary head.
As we are pumping grout to the bottom of the pile, the water in the pile is forced to surface, making the site very wet, so a good piling mat is needed, to maintain a stable platform for safe manoeuvrability and consistent verticality of the piles.
Continuing the Contiguous Piled wall through restricted areas is no problem, even with delicate masonry and protected trees undamaged.
Although the clay looks very good from this photo, in some areas of the Contiguous Piled wall, we came across large boulders of Ironstone (Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron compound from which iron either can be or once was smelted commercially). Which is extremely hard and very common for this area of Oxfordshire; we were unable to auger through these obstructions which were located around 4.0m from ground level, so excavation was not viable. With discussions and transparency from us at Advanced Mini Piling Systems with the client, we were able to agree a solution for the obstructed piles numbering 7 in total. Ours and the clients engineers omitted the 7 number piles and redesigned the R/C works.
Clapham common Basement:
This was a very challenging site, with tight access on a small street, and a very small open site. The property is a modern three storey town house which was built in 2006 and was built off piled block and beam foundations. A single storey extension to the side of the property was demolished, and the piles and beams removed, to allow for the installation of a Contiguous piled retaining wall, to be installed around the perimeter of the garden, once excavated this would give the client a basement and access to excavate under the rest of the house.
Because the property is built off piled reinforced beams, these would support the building while the R/C works are taking place, and removed once the transfer slab is completed. Although the site was very narrow about 4.0m we managed to complete the piles using are largest piling rig, this allowed us to work more efficiently, as we could have the reinforced cages fabricated on site, to the required length of 10.0m, which could then be winched in to the open bores in one lift. Also our daily meter rate is higher and it requires less labour than smaller rigs keeping down costs.
Scope of works;
*Mobilise to site 14.0 t Doosan Kelly bar rig on a low-loader.
*Welfare facilities provided by main contractor.
*Loading plan put in place, with protection to the drive way.
*Safe working zone for steel fixers.
*Site marked out by main contractor using 500mm pins with caps on.
*Required number of piles installed and concreted.
*Site, pavement and road cleaned on a daily basis.
To Provide 21 piles to rebuild a garden wall; the existing wall had fallen down due to the tree roots, and the weight of the garden it had been retaining for many years. As we were working on the party wall, permission had been granted from both sides to gain access to work. All materials and machinery would be brought through the garden, of the property at the top side of the wall, and a safe working area would be made in the garden of the bottom property.
Before work could commence trial pits had to be dug, by hand to find out where the roots of an oak tree with a TPO (Tree Preservation Order) on it were, which prevented damage to the tree roots while removing the existing wall, and while piling. The piles, beams and beam heights were determined by the location of the tree roots, the beams will bridge the roots so no piles or excavations would damage them.
Although this is not a Contiguous Piled retaining wall, which would of been more expensive, the engineer choose to design the piles to take a hollow block wall, which would be slotted onto reinforcement cast int the beam, and then filled with concrete. The piles were placed in pairs and will take lateral and vertical load, tied together with a 600×400 capping beam.
Due to ground conditions here, the decision was taken to Tremmie all piles rather than use Hollow Stem flights, as this would help to reduce mess from waste water in the cleaning process after every pile, and the clay was stiff enough to stand open while grouting.
Scope Of Works
*Site health and safety and welfare facilities provided by main contractor.
*Mobilise Kitten Piling Rig to site with grouter.
*Garden protected and ramp made to remove spoil.
*Safe working area set up for Steel fixing and use of grouter,
*All cement and sharp sand to be moved by hand to the rear of the property.
*Garden of bottom property fenced off and piling mat installed.
*Piles and pile heights set out by main contractor.
*Install all 21 piles to engineers specifications.
*Clean and clear site, demobilise rig.
All cages tied and protection boards taken up every night to prevent killing the grass.
The grout hose is placed to the bottom of the pile, which brings the water and debris out of the top, the cages are then plunged into the pile.
All piles complete and left at differing heights to allow easier cut off for the client.
As main Piling contractor on this project we were required to provide a Contiguous Piled retaining wall, around the perimeter of the property. The property is a five storey, end terraced house in the heart of Nottinghill. The side access to the garden, was 2.5m wide which, restricted the size of Piling rig we could use onsite.
The basement on this project, will be two levels, with the first level as living quarters, and the second as plant and storage rooms. This meant that the retained depth changed where we stepped down for the double basement, so our Contiguous Pile depth ranged from 8.0 – 15.0m. And as we are a smaller company, with a hands on attitude our engineer was onsite to over see most of the Piling works which enabled us to sort out any problems quickly keeping the programme within time scale.
The whole house is to be put on a transfer slab extending the basement, beyond the footprint of the house. Which required us to install temporary Bearing Piles to take the load of the house while the basement is being excavated. There are also a number of internal and external Tension Piles and internal Compression Piles to take loadings of 200kn at sub basement level.
Scope of works:
*Site welfare and Health and Saftey set out by Main contractor.
*Mobilise T5000 Auger Rig and 300mm dia solid stem augers to reach design depth.
*Steel and safe area for making cages was set up.
*Dumper for concrete with a chute.
*Lifting frame with 110v winch to safely lower cages for Internal Piles with minimum headroom of 2.3m.
*Complete all external Contiguous piles and Tension Piles.
*Install Contiguous Piles to form sub basement, which will join up with deeper external piles.
*Install Temporary Piles which will support the transfer slab while Sub basement is being excavated.
*Install Bearing Piles with a design depth to take 200kn.
*Clear site and demobilise T5000 Auger Rig and all other equipment.
On our first visit to site our engineer checks access, and the centre lines of piles so we can decide which Rig would be most efficient onsite.
T5000 Auger Rig with outriggers and 300mm dia lead flight with a cutting head for London clay and mudstone.
All the walls had been underpinned by the main contractor, the Contiguous Piled wall had to continue between the remaining walls supporting the house which proved to be very challenging. Especially underneath the stairs to the front door, where we had to install 4 Piles, at our minimum working headroom 2.25m, which meant boring and casting 2 Piles a day.
All of the steel reinforcement for the Contiguous Piled retaining wall had, 6H16 @ 2.2m long in a H8 helical – 200mm O/D (overall diameter) and pitch of 150mm (distance between helix). The design depth for these Piles was 15.0m so we had to connect and lower 10 cages, in each open bore before casting the Pile. Our custom winch and lifting frame has a SWL of 500kg and makes this job very safe.
Contiguous Piles installed, cut and broken down ready for capping beam.
Advanced Mini Piling Systems operative, with a concrete dumper, is far more efficient than using wheel barrows, and a lot cleaner than using a concrete pump which requires a lot of water to clean, which we don’t need in the winter.
As you can see from the photo the reinforcement has not been cut down, saving the main contractor time and money when casting the capping beam. which shows we care about what we do, and we work with the client, not for them.
Part of the finished retaining wall to the basement, underneath the bay window, also acting as a fire escape.