IRFISHER: PILING WORK

Piling works is the most important work for a building.Today I like to share my experience for survising two kind of piles.One is driven piles and no 2 is micro piles.

Driven piling

One project for Masjid in Kelang
Under JKR
Using 175 mm x 175 mm square pile -set pile
Pegs of centre point always missing when want to start driven
Should control by theodilte or survey instrument for verticality
Connection between piles must cont' welding not spot welding
When piles near to set,stand by for set graph
At least 100 mm projection re bar from pile head
Survey piling point position before proceed with pile cap
If offset more than 75 mm for any direction,calculation pile capacity for group pile
For single pile,tie beam will produced

Micro piling

One project in Prima Saujana,Kajang
Initially using pre cast piles,soil condition full of loose rock
Using 250 mm diameter of micropile with metal casing
Drilling until 27 depth and casing will pull out until left 15 m from ground
Using grouting cement grade 40 and normal re bar
Cost about RM 1.8 m compare to driven piles at RM 200k

Sheet Piling

For monsoon drain at Shah Alam
Depth 12 m driven but only 6 m driven
Standing supervision is most important when piling works begin

Short piling

Happen when the soil condition very hard to penetrate
Short piling that means below 3m penetration
Replaced with deep pad footing

MOST IMPORTANT:

Piling set calculation for driven piles before begin driven works
Piling set graph must supervise by consultant
As Built Drawing for piling point must submit and approved before pile cap work begin

2.Piling Scope of Work

The building need to be pile because the top strata soil condition not have a enough strength to hold a building load.How do we know the strength of the soil?,Cant assume or see bye eyes only but need to test.They have 2 type of soil test.MacKinTosh and SPT test or Bore Hole test.The first one is the cheapest but 60% only the accuracy and not many data can get from this test.The Mackin Tosh will carry out as many point is needed and the result are read from blows/feet value.If value is 40 blow/feet is equavalent to 100 kn/m2 ,value from JKR table and footing are suitable for this reading and for value 15 blow3s/feet then piling works are needed.

Then the Borehole test will carried out to find out

type of soil 👈 water level 👤 SPT values 👰 soil sampel
real pile capacity👸soil parameter👱depth of pile to penetrate

The are so many type of pile at market.the most popular is precast pile whether square or spun pile.The other type is micro pile,bore pile,H steel pile and etc.The type of driven is hammer driven and jack in driven.Here only a square pre cast pile and using a hammer type of diven are disccused.

The works involve in piling work

setting out

using theodolite or classic method base on the architech drawing and pile group all the singe pile mark at the centre

pile driving

after all the pile centre and confirm.the pile have to drive.before that all the document such as SIRIM cert.piling set calculation must submit to the engineer.before that at the body of pile a 1 feet line will mark for overall length of pile.the lifting to position is very important because normally the other mark or pes will lost or missing when a first pile start to drive.the verticality have to check by a thedolite or water level.the driven pile have to record.when the pile start to bound when hammer it,the set graph are locate to the body of the pile.the reading must be tally with the piling set calculation.the piling work are carried out until finish.the connection between must continuous wel not spot weld.the verticality always to be check when a for every new connection of pile.

load test

they have 2 type of load test.the instant of PDA test .and 48 hours MLT test.The PDA not 100 % accurate compare to MLT but PDA must do when the piling machine still at the site.the PDA is primary result of load test.if the result is ok,the piling machine will be out but if the resultis not ok,the MLT will stanby at 48 hour to know the final load test.if ok that mean the machine can go out but if not ok,repiling or new design will be carried out.

excavation and pile head cutting

after confirm a load test are approved,the excavation work using an excavator started,for a pile group ,must be care ful when excavate between pile,usually use a manual and the excavation must be 20 % bigger than the pile cap size.the pile head cut will carry on later using a special tool and equipment and the level must be check correctly base on the architech drawing.100mm of protude bar is need to left it.

as built survey

after all the pile head done all the cutting work,the as built survey for all the pile to check whether all the single pile position in the centre,if more than 75mm,pile deavation (offset) calculation must be submit for group pile and tie beam calculation for a single pile group.