Rates, Norms & Durations / Building & Construction
Foundation Works
Elements relating to substructures / foundations...
17 entriesSource page: Foundation Works
Subjects on this page
| Activity | Entry (verbatim) | Value | Source |
|---|---|---|---|
| Barrette Piles | Barrette PilesTask / DescriptionSlow Ave Fast Units Rule of Thumb, overall rate by Mill0.5 1.1 1.2 hrs/no Fabricate reinforcement cages- 4.0 - hrs/cage Concreting barrette panels40.0 50.0 55.0 m3/hr Trimming top of barrette panels- 2.4 - days/no Concrete Testing, Coring Test4.0 3.5 2.0 days/no Concrete Testing, Sonic Logging Test- 0.7 - days/no | 55 m3 per hrper hrParsed | Barrette Piles |
| Bored Piling | Pre-Drilling - Site Investigation Pre-boring will be carried out at each location to ascertain the target founding level. Rotary rig drilling operations incorporate the use of a steel core that is used when a core sample is required. Another type of boreing is called “Wash Bore” or “Percussive Bore” which simply means that a bore is flushed out and is used when no soil sample is required. Typical rates are... Type of Strata Plant Used Rate (m/hr) Top soft deposits of site fill Percussive / Rotary 10.00 Grade V/IV rock deposits Wash Boring 3.15 Triple Tube Sampling 0.75 Grade III/II rock deposits Rotary 0.50 Triple Tube Sampling 0.50 With a standard rig, working a 12 hour shift, a typical output rate of 66 hrs/hole/rig is possible. As-Built Information. On Central Reclamation, Contract UA11/91, borehole drilling completed with the following results... Average depth of 61.15 m, total depth of 428 m Average rock socket depth of 4.65 m The durations ranged from 4 to 8 days Average of 5.85 days, total duration of 41 days. The Target Founding level This is defined as the required socket into the bedrock, which is defined as moderately decomposed rock grade III or better with a core recovery greater than 85% (allowable bearing capacity of 5 mPa). The continuity of the founding rock is demonstrated by continuing the pre-bored hole a maximum of 5 metres or 3 times the pile diameter, whichever is the greater. The cores are logged, stored and photographed and submitted together with proposed founding levels for approval. Setting Out Before starting excavation at the pile position the following steps are taken: Survey and record the existing ground level at the pile position Setout the pile location from the reference points and in order to monitor the position of the steel casing, control pins are usually established at two orthogonal positions, offset from the centre of the pile. Pile Tolerances In the case of out of position casings, adjustment can be made to keep the vertical alignment and plan position within the limits of no more than 75 mm off-centre on plan position and not deviating by more than 1:75 from the vertical axis. Pile Excavation / Casings The shaft of the pile is excavated within a temporary steel casing with an outside diameter of say approximately 200 - 300 mm greater than the pile diameter. The casing is used mainly in areas of unstable ground and are driven using hydraulic casing oscillator attached to a crawler crane or a casing vibrator. Shaft excavation is carried out using a single or double hammer grab supported by crawler crane. The steel casing toe is kept in front of the excavation level until it is 0.5 metres above the pile cut-of level. The pile shaft is often flooded with bentonite or water and excavation proceeds to the top of the CDG. Excavation then proceeds by reverse circulation drilling (RCD) using large diameter drilling heads with special rock cutters and flushing by air lift. Bentonite or water levels are always maintained above the ground water level to ensure stability of the shaft. Calculation Of Bored Pile Construction / Excavation Time Piling times can be reduced by the use of service cranes for reinforcement and concreting activities. An additional extended shift would often be required for certain piles, as would RCD down-time. Forecast construction times can be derived by using output rates (hours per item)... Operation Element Details Hours Add or Remove Reverse Circluation Drill Plant (RCD) incl drill bit 2 hrs Add or Remove RCD drill bit (incl assembly of drill string) 5 hrs RCD bell-out bit (incl drill string & stabilisers) 5 hrs Installation Airlift tremmie tube 5 hrs Reinforcement cages (time for joining each cage) 2 hrs Cleaning Time Initial airlift cleaning (after finishing excavation) 8 hrs Final airlift cleaning (after fixing steel cage) 2 hrs Concreting Incl extract casing ( < 70 m deep) 12 hrs ( > 70 and < 95 m deep) 14 hrs ( > 95 and < 135 m deep) 48 hrs Curing Time Only required prior to removal of telescopic casings 72 hrs Cycle Time Move piling setup to next location 2 hrs Shaft Excavation Strata Plant Used Rate (m/hr) General Fill (upper ground levels) Grab 3.50 m/hr Sand, Minor Rubble Grab 2.10 m/hr Marine / Alluvium Deposits Grab 2.50 m/hr CDG < 150 RCD/Grab 1.50 m/hr CDG > 150 < 200 RCD 1.00 m/hr CDG > 200, Compacted Gravel RCD 0.50 m/hr CDT RCD / Grab 0.50 m/hr Corestones RCD / Chisel 0.50 m/hr Rock Socket - Grade IV/V RCD 0.25 m/hr Rock Socket - Grade II/III RCD 0.125 m/hr Rock Socket - (Tendering Rate) RCD 0.10 m/hr Forecast excavation or cycle times can then be derived by analysing ground conditions. Site investigation will provide the depths / types of strata which can then be matched to production output rates (see above). Note - A pile’s diameter has negligible effect on production time and as such is ignored. Example - For a pile founding on rock at 60 m deep... (a) Calculate Allowance For Plant Time / Other Elements (hrs).... Element Hours Set up RCD 5.0 Excavate Time See Below Remove RCD (including drill bit, string and stabilisers) 5.0 Setup / Remove Airlift Tremmie Tube 5.0 Initial Post-Excavation Airlifting 5.0 Place reinforcement (5 No cages @ 12m = 5 x 2 hrs) 10.0 Setup / Remove Airlift Tremmie Tube 5.0 Final Post-Reinforcement Airlifting 2.0 Concrete and remove casing 12.0 Move to next location 2.0 Calculate Total Construction / Plant Time 52.0 hrs (b) Calculate Allowance For Excavation Time (hrs)... Depth of Strata (m) Type of Rock Production Rate (m/hr) Plant Used Time (Hrs) 0 - 20 Sand/minor rubble 2.00 Grab 10.0 20 - 35 CDG less than 150 1.50 RCD/Grab 10.0 35 - 47 CDG more than 150 1.00 RCD 12.0 47 - 57 CDG > 200/corestones 0.50 RCD 20.0 57 - 60 Rock socket 0.20 RCD 15.0 (c) Calculate Total Pile Excavation Time = 67.0 hrs (d) Overall Pile Time Construction / Plant Time (“b” above) 52.0 hrs Excavation Time (“d” above) 67.0 hrs OVERALL CYCLE TIME (“b” + “d”) 119 hrs (With 12 hr shifts) (“b” + “d”) 9.9 days Bored Pile Construction As-Builts General Rule of Thumb Pile Times (days)... Depth (m) => <20 <40 <70 <90 <135 Days Per Pile 4.0* 8.0 10.0 25.0 45.0 Note - due to the required plant assembly and operation times, 4 days is the minimum possible pile construction time for any situation. Methods For Overcoming Obstructions If the obstruction is shallow (ie 0 to 2.5 m below ground level) a backhoe-breaker will be used to form a suitable hole. Where the obstructions are located at greater depths an oversized temporary casing is driven by the oscillator to the top of the obstruction. If the obstruction is above water level a hand operated air hammer is used, a typical rate of = 0.8 m/hr If below water level a down the hole hammer or heavy chisel supported by crawler crane will be used, a typical rate of = 0.5 m/hr If a concrete “plug” is required to provide a well formed shaft wall when an obstruction or excessive overbreak or fault is encountered... Element Hours Remove RCD 5 hrs Install Tremie Concrete Tube 5 hrs Place Concrete Plug 2 hrs Cure Concrete 36 hrs Replace RCD and drill string 5 hrs TOTAL TIME LOSS 53 hrs (2.2 days or 4.4 shifts) Cleaning of Pile Base The hole of the pile shaft is cleaned using an airlift until the water becomes clean or negligible particles in suspension is discharged. Reinforcement Cages Cages are constructed in suitable sections, usually in the order of 12 m long, complete with sonic tubes and coring tubes. Fabrication, 12 m long cage with 6 no fixers... Fabricate 1 cage 2.5 hrs Total cages required 5 no Overall Fabrication Time 12.5 hours Steel Stanchion Fabrication and Installation Stanchions are usually fabricated off-site and delivered in sections. Prior to installation the sections are welded together to form the complete stanchion. Stanchion sizes are usually in the region of 525 mm x 525 mm. With an average length of say 28 m, the welding time would be around 5 days and are tested by an ultrasonic weld test and an MPI test. After the installation of the reinforcing cage in to the shaft the stanchion will be lifted until it hangs vertical. It is then lowered into the excavation and clamped into position. Concreting Pile concreting is carried out under water by "tremie" techniques maintaining the water or bentonite head inside the casing at or above existing ground water level. The tremie tube (250mm) is withdrawn as concreting proceeds ensuring a minimum concrete head of 2 metres above the top of the tremie tube. Sequence Of Piling The sequence of construction of piles is chosen in such a manner that no damage can be caused to nearby piles still under construction or recently concreted (i.e. less than 3 days). On a 12 metre grid, a normal layout would mean say having two non-worked on piles between each open excavation in the longitudinal direction (ie a 36 metre spacing) thus allowing room for the crane etc and a lesser spacing of every other pile being worked on (ie a 24 metre spacing). Pile Testing The workability of concrete is tested on site by measuring the slump and temperature of concreting at the time of discharge into the pile shaft. Laboratory tests are carried out in order to check the strength of the placed concrete. A number of test cubes are made and tested at 7 and 28 days. Coring Test - Certain piles selected by the Engineer will be cored their full depth. The depth of cores into the base material (rock) will usually be at least 600 mm. Cores are placed in correct order and relative position in core boxes which clearly mark the depths of cores. The cores are usually photographed and submitted to the Engineer. The testing of the coring will provide additional information about the quality of the concrete as well as the condition of the interface between concrete and rock. Sonic Logging Test - In order to test the quality of the concrete as well as the integrity of the pile in its overall length and pile toe condition sonic core testing is used. Sonic tubes are installed with the reinforcement cage in order to allow the lowering of the signal transmitter and signal receiver probe down the bottom of the pile. These tubes are sealed at the bottom. Vibration Tests - This test determines the pile length and shape and the overall pile concrete quality. This is a specialist test.13 rate statements found; left for an editor | — | Bored Piling |
| Contigous Piling | Principles of Construction Often known as "Colcrete" piling, which is a type of trade name. Usually replaced by diaphragm walling methods.Essentially typical bored piles, or down-the-hold bored piles, are constructed with a spacing such that each pile is virtually touching the next. These are constructed on a hit-and-miss basis.After a suitable length of these piles are in place (often 9 piles or so) a smaller drilling rig follows on behind placing the "colcrete" piles. A small diameter shaft, often 100 mm or so, is drilled on the external face of the pile wall close to the interection between the two main piles. This excavated pile is fitted with a grout tube and backfilled with gravel. The pile is then grouted and forms a seal between the adjacent piles. This type of pile wall can be constructed with either a standard reinforcement cage or a "H" pile.Info below achieved on project in Bermonsey, London - Sept 2010 1 rig, 600dia contig piles, 12-15m deep, 12No per day (average), 15No per day (max)Rule of thumb based on Hit 1, Miss 3 = 8.5l/m day per rig.Labour: 1 Rig driver, 1 banksman, 1 conc pump operative, 3 x steel fixers, 1 x 360 driverPlant: 1x rig, 1x mini 360 exc, 1x 6m3 mixer, 1x pump, - Deliveries: 4 - 5No 6m3 wagons per rig per day (av 2m3 per pile)Mobilisation: 1 day (Allow for 2 days)Next trade - Excavate and blind around piles (for ring beam) - start 7 elasped days after last piles in the run are complete (4 working and 7 elasped days after piling start based on Hit 1 miss 3 method and 12No/d). 34 linear metres released for Groundworker to start.All piles 600mm in dia. No smaller piles or grout tubes used as described in the post by technical development. The face of the basement wall will be faced with a single skin of blockwork at a later date (non critical).Method: Hit 1, Miss 32 rate statements found; left for an editor | — | Contigous Piling |
| Diaphragm Walling | — | Diaphragm Walling | |
| Driven Piles | West Piling (P.C. Shells), Rate of 100 m/day Balken Piling (Solid P.C. Pile), Rate of 120 - 135 m/day H-Piling, Rate of 200 - 500 m/day3 rate statements found; left for an editor | — | Driven Piles |
| GroutingGrouting Operations | Vertical Grout Curtain Application of grout curtain. A typical rate of 6.20 hrs/m run. | — | Grouting |
| Hand Dug Caissons | Principles Of Construction This type of "pile wall" is typical employed in areas where headroom or proximity to buildings restricts the use of large diameter bored pile drilling rigs, or where the wall is to be located very close to an existing structure. These are very time consuming and in allot of areas no-longer allowed as an acceptable safe construction method. Stringent air monitoring and safety isses are adhered to during the construction of the caisson. An electric chain block and hoist structure is maintained at the pile head for access and egress of both materials and operatives. Site Investigation / Advanced works Advanced grouting is often carried out around the group of caissons in order to reduce water inflow into the caisson area and provide adequate safety factor against base heave failer. Grouting of the area will also restrict ground settlement due to changes in the water table during caisson construction. A 75 mm diameter grout hole is drilled to 2 m belowthe specified toe of the caisson. On completion of drilling, a 40 mm inside diameter PVC, Tube-a-Manchette (T-A-M) grout tube will be installed to the bottom of the grout hole. The tube is usually perforated at 300 mm intervals with each perforation being covered by a tightly fitting rubber sleeve to act as one way valves. The grout hole is often backfilled with gravel and then pumped with grout to the specified pressures etc.. After each stage of grouting the T-A-M will be flushed with water to allow future grouting as necessary. The slightly conical excavation core is carried out by hand and a formwork erected and concrete placed in the void between the excavation and the internal formwork. Excavation down to the next level then begins. Excavation Of Caissons All excavation is carried out with air tools and shovels etc. Material is loaded into a 0.2 m3 drum skip. Hand excavation to a depth not exceeding 1 metre. Fix a suitably braced 3 segmented tapered shutter, fix reinformcement and pour concrete to fill all voids between the external face of the lining and the earth face. This operation is undertaken continously until the founding level is reached. Steel Reinforcement Reinformcement is placed either in prefabricated cages or directly erected in side the bores, depending on headroom and caisson access conditions. In some instances a steel "H" beam is installed in place of a reinforcement cage. Concreting Concrete is cast in place in one continuous operation using the tremmie pipe method, up to cutt-off level. The concrete is generally not vibrated. As-Built Examples Perimeter wall caissons, 800 mm diameter, excavated to a depth of 26 metres (HK Central Subway). Excavation Time 18 - 24 days Excavation to Concreteing Time 26 - 35 days Difficult ground of sea wall or ground obstructions can easily increase theoverall construction time to 50 or 150 days. | — | Hand Dug Caissons |
| Mini Piling | Mini Pile Construction Small diameter piles quickly driven into position, with suitable concrete pile cap. Diameter Depth Hrs per pile m/hr depth 235 mm 35 m 40 hrs/no 0.87 m/hr | 0.87 m per hrper hrParsed | Mini Piling |
| Multiple Bell Ground AnchorsGround Anchors | Multiple Bell Ground Anchors Often used in London Clay. Uncased, 10 m long 2.0 no/day Top Cased type, 15 m long 1.0 no/day Anchor Stressing 2.0 no/day3 rate statements found; left for an editor | — | Multiple Bell Ground Anchors |
| Removable Ground AnchorsGround Anchors | Removable Ground Anchors Recent innovation of "removable" ground anchor system. Steel cables are doubles up and threaded over a roller at the anchor end. Once de-stressed, they can be pulled out. 1 rig can achieve... Drill 30 m shaft 7.0 hrs Install strands/setup anchor 6.0 hrs Grout in strands 2.0 hrs Stressing can be done 4 - 7 days after grouting. Usually at 3 m horizontal centres and can only be worked on with 5 - 6 m spacings. So a hit and miss method must be adopted, giving a significant programme constraint. | — | Removable Ground Anchors |
| Secant PilingSheet Piling & Strutting | Secant Piling...Task / DescriptionSlow Ave Fast Units Construct 30m dia cofferdam, 255 piles/concrete base- 12.0 - wks | — | Secant Piling |
| Secant Piling | Principles Of Construction Often known as "Benoto" piling, which is a type of trade name. Usually replaced by diaphragm walling methods. Essentially typical bored piles, or down-the hold type bored piles, are constructed with a spacing slightly smaller than the chosen diameter of the piles. Once a suitable length of piling has been completed, the "holes" are filled with a similar bored pile which intersects and "bites" into the two previously constructed piles. Usuall these piles are strengthened with a steel "H" pile, rather than the typical reinforcement cages used in standard bored piling. As-Built Examples Large diameter circular secant pile cofferdam. Structure consisting of 1,200 mm diameter secant piles to a depth of 20 which then stepped into 900 mm contiguous piles for a further 20 m depth. Each pile was probed to 10 m depth in advance. A total of 255 number piles were constructed. The "cofferdam" had a 1.4 m deep concrete base slab with a concrete lining to the walls. An intermediate concrete roof slab was placed to form an underground box structure. Overall construction time 12 weeks (Heathrow Express). | — | Secant Piling |
| Sheet PilingSheet Piling & Strutting | Sheet Piling On reclamation, sand fill, sheet piling by crane and drop hammer, vibro hammer or diesel hammer.A rate of 20 - 25 No/day to 20 to 35 m deep.1 no = 0.4 m wide on plan and 6 m long.Therefore 8 - 10 m/day per rig is achievable.On more difficult areas, such as through existing ground or a sea wall for example.A rate of 10 - 12 No/day to 20 m deep.Therefore 4 - 6 m/day per rig is achievable.For more shallow sheet pile wallsDriven by - Pilemaster 60.0 m/dayDriven by - Automatic Drop Hammer 32.0 m/daySteel for piles is usually readily available and a two week lead in is often all that is required.Sheet PilingTask / DescriptionSlow Ave Fast Units Vibro/Drop Hammer, 10m deep Sand- 55.0 60.0 m/day Vibro/Drop Hammer, 35m deep Sand3.5 32.0 10.5 m/day8 rate statements found; left for an editor | — | Sheet Piling |
| Slurry Mix WallSlurry & Soil Mix Walls | Slurry mix wall (for noise restrictions/obstructions) grab excavation to full depth, fill with cement or bentonite mix, drop and hold sheet piles in place.Excavation 1 panel (4.5 m long on plan) with grab and crane.Excavate 1 panel in 2 days + 1 day bentonite and sheet pile, giving a rate of 1 - 1.5 m/day.Therefore, once started 2 - 2.25 m/day is expected.Slurry Mix WallsTask / DescriptionSlow Ave Fast Units Crane grab, cement/bentonite and sheet piles1.8 2.5 3.4 m/day3 rate statements found; left for an editor | — | Slurry Mix Wall |
| Soil Mix WallsSlurry & Soil Mix Walls | Soil Mix Walls...Task / DescriptionSlow Ave Fast Units Three Auger Drill, cement and cure3.8 4.5 6.4 m/day | 6.4 m per dayper dayParsed | Soil Mix Walls |
| StruttingSheet Piling & Strutting | Strutting To install simple horizontal heavy duty strutting, a typical rate of 2 days per strut/gang is reasonable. To install diagonal slab/roof cross-brace strutting, a typical rate of 6 days per strut/gang is reasonable. To remove these struts, allow a rate of 3.5 days per strut. | — | Strutting |
| Underpinning | Concrete Pinning - During underpinning operations a cycle of every 4th or 5th pin being constructed concurrently is adopted.Rate of 1.2 m/day, i.e. 1 number support pin per dayUnderpinning...Task / DescriptionSlow Ave Fast Units Concrete Pinning, 4th or 5th pin cycles- 1.2 2.2 m/day Brickwork Pinning, 1.0 brick thick- 0.4 0.7 m2/hr Brickwork Pinning, 1.5 brick thick0.1 0.3 - m2/hr Brickwork Pinning, 2.0 brick thick- 0.2 - m2/hr Wedge and Pin Method, 102mm wall- 0.8 - m/hr Wedge and Pin Method, 215mm wall- 0.7 - m/hr Wedge and Pin Method, 317mm wall- 0.5 - m/hr3 rate statements found; left for an editor | — | Underpinning |
1–17 of 17
These values were contributed by members and reflect the conditions, methods and regions they worked in. They are a starting point for estimating, not a standard. Check them against your own records, the site conditions and the contract before relying on them.