Bored Pile Foundation (Survey setting out, pre boring and casing installation)
Bored Pile Foundation (Survey setting out, pre boring and casing installation)
πSurvey Setting Out
Total Station αြα့် Pile center point αေαာαှာ αုα်αိုα်αါαα်။ αေးαα်αα်αေးαα်αှာ αα်း αα့်αα့်αုံ (2m~3m offset) αွာαြီး αံαုα်ααေးαွေαိုα်αားααα်။ Pre-bore αူးαြီး casing αျαျိα် Pile position αို Countercheck αုα်αို့ αြα ်αါαα်။
✔️Positioning of Drilling Rig
αိုα်αူးα α်α‘αွα် Level αီαျα်αှာαြα်αα‘ောα်αြα်αα်αားααα်။ αြေαားαျော့αျα် αံαြားαျားαα်းααα်။ α α်αို Pile point α‘αီးαှာ α‘αိုα်αျαြီးαျα် Drilling bucket center αှα့် Pile point center ααα်αα်း αျα‘ောα် αျိα်ααα်။ Pile position αှα်αြီαိုαျα် Pre boring α αူးαါαα်။ Auger (αို့) Bucket αြα့် αြေα‘αျော့ α‘αာαေါ်αူαα်αြီး αူးαြαါαα်။ Bore α αူးαာαဲ့ Bentonite slurry αို α αα်αြα့်αွα်းαါαα်။
✳️Casing Installation
Casing αိုα် αျαိုα်αဲ့ α‘αα်αောα်αျα် Casing αို Vibrohammer αြα့် αိαွα်းαါαα်။ Casing αα် Pile center αွα် αေαာαှα်αှိαေαို့ Verticality αျαို့ α‘αွα်α‘αေးαြီးαါαα်။ Casing αိုα်αာ Bored pile diameter αα် 50mm~100mm αိုαျα်αား αေ့αှိαα်။ 1-meter diameter bored pile αိုαျα် 1100mm dia casing αုံးαာαျိုးαါ။ α‘αေါ်αံ αြေαားαွေαာ Loose soil αွေαြα ်αို့ α‘αွα်ααူαြိုαျαိုα်αဲ့α‘αွα် Casing αံαိုα်αွေ αα့်αြီး αာαွα်αားαြα်းαြα ်αါαα်။ 3m~6m α‘αα်αα့်α‘αိ Casing pipe αျαေ့αှိαါαα်။ Casing αို αြေαြα်α‘αေါ် 300mm~500mm αα့် αြှα့် αားαြီး αေးαို αံααိα်αြα့် ααိα်αော်αာ αα ်αားαα်းαျားαြα့် αုαားααα်။ αောα်αိုα်း Casing αိα့်αျαွားαာαျိုးααြα ်α‘ောα် αျုα်αားαဲ့ ααောαါ။ Casing center point αို Total station αြα့် Final confirmation αုα်၊ αိုα‘α်αα် Position adjust αα်αုα်αြီး Pile αူးαြα်းαα်αα်αြုαုα်αါαα်။
πBentonite Slurry
Bentonite mixing tank αြα့် αြိုαα် αျော်α α်αားααα်။ αွα်းαဲαို့ ααြα့်αွα်းαီ αα်αှα် α ံαα်αိုးαျားα‘αိုα်းαှိααှိα α ်αေးααα်။ Density 1.04~1.1 α‘αွα်း၊ Viscosity 30~50 Sec၊ pH value <10.5, Sand content <3% α‘αွα်း αှိααှိαို Drilling αα αα် αှα့် Concrete ααောα်းαα် Slurry sample αူαြီးα α ်αေးααα်။ αα်αှα်αα်αိုးαျားα‘αွα်းααှိαါα α‘αျိုးα‘α ားαို αြα်αα် α α ်αေးαျော်α α်ααါαα်။ Bentonite slurry αို Drilling αုα်αေα α₯်αှα့် Concrete αောα်းαေα α₯်αောα်αျောα် αွα်းαဲαှာ α‘αြα့်αြα့်αေးαားααα်။ αို့αှαာ αွα်းαံαံ αြိုαျαာαွေ αα်αာα ေαါαα်။
(αα်αα်)
αွေαှိုα်α₯ီး (αြို့αြ αααα)
Bored Pile Foundation (Survey setting out, pre boring and casing installation)
Survey Setting Out
A peg is driven at the pile center point using a Total Station. Additionally, small iron pegs should be driven at a suitable offset (2m~3m) on all four sides. This is to countercheck the pile position after pre-boring and during casing installation.
Positioning of Drilling Rig
A level platform must be prepared for the drilling rig. If the ground is soft, steel plates should be laid down. Once the rig is positioned near the pile point, it must be aligned so the drilling bucket center is perfectly over the pile point center. After confirming the pile position is correct, pre-boring begins. Drilling is done with an auger or bucket depending on whether the soil is soft or hard. As soon as drilling starts, bentonite slurry begins to be filled in.
Casing Installation
Once the required depth for installing the casing pipe is reached, the casing is driven in using a vibrohammer. It is very important that the casing is in the correct position at the pile center and that its verticality is precise. The casing pipe is usually 50mm~100mm wider than the bored pile diameter. For example, a 1-meter diameter bored pile often uses a 1100mm diameter casing. This is because the surface soil is often loose and can collapse easily; the steel casing pipes are installed to prevent this. The casing pipe is typically installed to a depth of about 3m~6m. The top of the casing is left about 300mm~500mm above ground level and is then braced laterally with a steel frame and wooden planks to secure it. This is to prevent the casing from sinking later on. The casing center point is given a final confirmation with a Total Station, any necessary position adjustments are made, and pile drilling continues.
Bentonite Slurry
The slurry must be pre-mixed in a bentonite mixing tank. Before it is pumped into the hole, it must be checked to ensure it meets specified standard values. Whether before drilling starts or before concreting, slurry samples must be taken and tested to be within these ranges: Density 1.04~1.1, Viscosity 30~50 Sec, pH value <10.5, and Sand content <3%. If the values are not within the specified ranges, the mixture must be checked and remixed. The bentonite slurry must be continuously kept full in the hole during both the drilling and concreting processes. This helps minimize the risk of the hole walls collapsing.
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