Archive for the piled retaining walls 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.
Jurassic Coast, Contiguous Piled Wall, Branscombe, DevonProject Brief:The site is situated on the side of Branscombe cliff, in Lyme bay. The cliff is made up of three strata, Chalk, Pre-Cretaceous Upper Greensand and Mercia Mudstone with gypsum from the Triassic era. Originally Branscombe grew from mining gypsum and the property we are working on was terraced workers cottages, with the look out on the end, a coastguard station.The Jurassic coast is a world heritage site and the rock and cliff formations have been changing for millions of years, with land slip a very common problem. Only 1km down from the site is Hooken cliffs where in the 1800’s a landslip took place containing a few million tons of chalk slipping off the Triassic Mercia Mudstone, this continual changing coastline means we need to find modern answers to solve a very old problem.This project comprise of installing a Contiguous Piled Wall in front of an old coastguards lookout, the lookout which is no longer used by H M Coast guard and is now part of private home and has been converted to suit the clients needs with a large decking, cantilevered over the cliff edge. In front of the building was mass poured concrete to retain the cliff edge and support the decking, unfortunately due to weather erosion the concrete has cracked up and is slowly slipping down the cliff, leaving the footings of the old lookout exposed.In an attempt to prevent any further movement, the whole cliff has been rock anchored and netted down while works continue. With the original decking removed scaffolding had to be erected to allow for the piling rig to work in front of the building, the scaffolding had to support a 4t point load and every other support was placed on a rock anchor.The machine we used for this job is a PPS Unwin Kitten Rig which is capable of working in restricted access conditions, and very powerful and able to bore through the tough layers of limestone. The Kitten is also able to install Temporary Cased Piles, which we are using for the bearing piles 1.5m from the centre of the Contiguous Piled Wall, this places them in the middle of the scaffolding, and any spoil or concrete would fall down the cliff causing a safety hazard. Site access and weather conditions also made this a challenging job for our team, All our equipment and reinforcement had to be delivered by 7.5t lorry as roads to site were very narrow. as the winter storms of 2014, with high tides and storm force 10 and 11, for some days the wind speeds reached 90mph with driving rain on the unprotected cliff face work had to stop as just standing up became a problem. Although we were unable to work on site, we helped clear debris from the road, restaurant and secured loose boats and peoples belongings. The high tides and high winds had washed most of the service road away which leads to several beach chalets, which were also damaged, and only 25m below our site. Storm force 10 and abnormal high tides, cause major problems on the beach front.The service road and some of the chalets have been washed away. Scope of works:* Site canteen and welfare facilities provided by main contractor.* Protect all walls and drive where we are working.* All services located and isolated.* As we are working on a cliff face all safety handrails must be installed and checked.* Mobilise PPS Unwin Kitten Rig, by 7.5t lorry.* PPS Unwin Kitten Rig chained with tether while on scaffolding.* Prefabricated 6H16 – H8 helicals @ 200mm pitch, delivered to site by us.* Pile positions set out by main contractor.* Safe route for concrete deliveries planned, and lorry walked to site by banksman.
The Contiguous Piled Wall continues along the front of the garden, although here we are working in between four cantilever beams which hold the decking over the cliff, so we are installing three Piles in each section. Because the spacing between the Cantilever beams was to small, the third Pile was installed custom essays behind the face of the wall giving it the same lateral restraint.
The Contiguous Piled Wall is installed at 600mm from the centre of the piles, to the face of the Look Out, top of reinforcement is finished at 1200mm from piling platform to allow for protrusion into 600mm x 600mm R/C capping beam.
Installing 300mm dia Temporary Cased Piles here with the Kitten Rig Prevents the spoil and concrete from falling down the cliff face, and means no operatives need to come off the scaffold.
Casing is socketed into the clay to form a seal and the pile is then formed with the casings extracted straight after concreting. These piles will have pile caps formed on top of them, which will support the new decking. Site is left clean and tidy after each day, with the access to the main house kept open and the drive power washed.
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.
Dunkeswell Bridge, Devon is an old stone built bridge which has become structurally unstable caused by the increased weight and traffic of this small arch based bridge. Unfortunately the road was closed until all works had been completed, the contract had to be finished in a short time, scale safely and without causing further damage to the bridge while it was being used as a work platform.
Scope of works:
*Install 12 No. 273mm dia Steel Cased Bottom Driven Piles to a designed set.
*Insert 12 No. 150mm dia 6mm walled steel Reinforcement.
*Concrete all piles to top of capping beam.
*Leave one chosen Pile up 500m from CSL to be tested by request of main contractor.
The road to Dunkeswell in closed untill all works are complete, by main contractor South West Highways allowing only pedestrians and cyclists safe passage. Which is why barriers and welding screens were used to prevent harm to the public.
The arch of the bridge is supported temporarily, while work goes ahead on top. And once the slab is cast over the piles the load will be transferred to them via the capping beam. Leaving the stone arch and sides of the bridge untouched.
The D1000H with built in hydraulic welder, and out riggers make for a very safe machine while operating over an excavated pile position.
All 12 piles installed to design depth, some of the driven piles had to be moved due services running under the road surface. The piles either side of the bridge, as they were being driven displaced the ground and put pressure on the sides this was also taken into account by moving them inwards.
A 150mm dia steel tube with a 6mm thick wall was inserted into each completed pile. Special skid spacers were welded to the sides of the reinforcement tube giving the correct concrete cover.The reinforcement goes top to bottom and is left 500mm below CSL which is top of capping beam, the piles were then filled with high slump, high strength concrete.
No pictures were taken of finished piles as heavy showers in the afternoon caused flash floods resulting in the road turning into a river which consequently ended in a number of piles filling with water, these were pumped out and were then ready for concreting.