Bored Pile Procedure 4. Removing slime when finish drilling, we use Mechanical pump equipment to remove slime.
Bored Pile Procedure 5. KODEN Test KODEN test utilizes the principle of ultrasonic wave travel from sensor to the wall of drilled hole and reflect to the sensor through the bentonite slurry. Equipment KODEN equipment consists of two parts, recorder unit and winch unit. Recorder UnitWinch Unit
Bored Pile Procedure Recorder unit controls the operation and record the test result. On the other hand, winch unit lowers the probe (sensor) down the hole for ultrasonic reflection. Testing Procedure 1. Remove any obstacle around the hole area in order that the test equipment can access to the hole. 2. Place the winch unit over the top of drilled hole or on the steel casing. Position the sensor (probe) at the center of the hole. 3. Lower the sensor into bentonite slurry. Hold the sensor at depth approximately 1 to 1.5m. 4. Restore the sensor to the starting position and perform the test.
Bored Pile Procedure Test Result Test results are presented in graphical plot and show characteristics below : 1. Profile along two perpendicular axes. 2. Average verticality of the hole. 3. Location or depth where abnormality Occurs such as reduction in diameter, or collapsed wall of the hole. 4. Depth of drilled hole.
Bored Pile Procedure 6. Insert of steel cage
Bored Pile Procedure 7. Insert Tremie
Bored Pile Procedure Type of tremie pipe : we have 3 types of tremie : 1m, 2m and 3m Length 3m Length 1m Length 2m Length
Bored Pile Procedure How to insert tremie pipe : 1. Use mobile crane to hang the hopper 2. Then connect each tremie pipe 3. After that put it into the bored pile hole until bottom When we pour concrete, we have to bury the tremie pipe into concrete as below : Diameter of Bored Pile Buried Length of Tremie Ø 10003 to 3.5m Ø 18002 to 2.5m
Bored Pile Procedure 8. Pouring the concrete Quality of Concrete : Max. size of Aggregate : 2.5cm Workability : 55cm ( Flow )
Bored Pile Procedure Strength of concrete : Design strength : fck =300kg/cm² ( 28days cure concrete ) Strength of mix ( Target Strength ) : according to the Standard Specifications of Concrete ( Korea Concrete Institute ) Strength of mix ( Target Strength ) So, for Actual Concrete Strength : 400kg/cm² MaterialStrength Calculation offck ( Mpa )Strength of mix ( Mpa ) Target Strength21 > fckfck + 7 ( Standard specifications of concrete ) 21 fck 35fck + 8.5 ( Korea Concrete Institute )fck > 35fck + 10 fck300kg/cm ² = 29.42 Mpa Strength of mix 29.42 Mpa + 8.5 Mpa = 37.92 Mpa = 389 kg/cm ² Apply : 400 kg/cm ²
Bored Pile Procedure 9. Remove casing
Cycle Time of a Bored Pile Step of Bored Pile Cycle time of each step ( hour) 1. Set up location of Bored Pile0.3 2. Inserting Casing2 3. Drilling8 4. Removing slime1 5. KODEN Test1 6. Inserting Steel Cage2 7. Inserting Tremie Pipe1 8. Pouring the concrete2 9. Remove casing1.5 Total Cycle Time18.8