CONSTRUCTION PROCEDUREFlow Chart :

1.Prepairation work

2.Setting out pile center

2.Setting drilling machine

• Survey inspection of pile center• Location, top level, gradient of casing pipe• Inspection of bentonite slurry

4.Pre drilling and installing casing pipe

Survey inspection of pile center

• Checking vertical direction• Checking horizontal direction

5.Drilling work(Up to design depth)

6.First cleaning

7.Fabrication of rebar cage

8.Installation of rebar cage

9.Setting tremie pipe

10.Second cleaning

11.Casting concrete

8.Removal of casing

1. Prepairation work:- construction plan must be surveyed carefully,including all obstruction under ground.- Construction plan must be leveled off.- All obstruction must be removed from construction plan. Such as: house’s foundation, water pipe, electric

cable...etc.- Seting up tank system to contain bentonite slurry or polymier slurry.- Machine and equipment shall be arranged properly in order to make convenience for driiling machine during

operation.

Tank TankPrecipitationPrecipitation

TankTankPrecipitationMixing Circulation

Supply Pump

Mud Screen

Drilling by ED Bucket

Circulation PumpSand Pump

Pump

Another

TankWasteWithdrawal

Tank

Concreting

tank

REBAR FABRICATION AREA

Tank TankPrecipitationPrecipitation

TankTankPrecipitationMixing Circulation

Supply Pump

Mud Screen

Drilling by ED Bucket

Circulation PumpSand Pump

Pump

Another

TankWasteWithdrawal

Tank

Concreting

tank

REBAR FABRICATION AREA

2. Setting out pile center :- The center point of the pile shall be surveyed by tachormeter and

marked by suitable stakes.- After setting casing, the pile center will be re-checked(level and co-

ordination) to confirm accuracy.

Pile Center

Temporary mark

3. Setting drilling machine:- Drilling machine will be set on the seel plate vertically and horizontally to keep stability during operation.- During operation, we must check the vertical and horizontal of kellybar of drilling machine.

Kelly bar

Drilling pointMark point

4. Setting casing:- We must check the length of casing and diameter of casing before setting casing: The length of casing depends on soil condition and undergroud water level. The diameter of casing bigger at least 5-10cm than diameter of bored hole.- After setting casing, casing will be inspected about co-ordination, level and vertical.

Casing pipe

5. Drilling work:- Before drilling, Bentinte slurry must be inspected:- According to Viet Nam construction standard, Specification of bentonite slurry shall be as follows:

No Property to be Measured Range of value at 20oC Test method

1 Density 1.05 ÷ 1.15 g/cm3 Mud density balance

2 Viscosity 30 ÷ 90s Marsh cone (700/900)

3 PH value 9 ÷ 12 PH Indicator Strips

4 Sand content < 6% Sand content set

6. First cleaning: After drilling, there is a lot of sediment(including soil and sand...etc.) in the bored hole. So that we must clean bored hole by pump or air compressor.

7. Fabrication of rebar cage:

- Fabrication of rebar cage will be carried out saprately from drilling work.

- Re-bar cage will be fabricated in accordance with approved working drawing and Viet Nam construction standard and inspected by engineer.

8. Installation of rebar cage:After inspecting rebarcage and completing first cleaning bored hole we will carry out installing rebar cage.

Re-bar Cage

Tremie pipe

 10. Second cleaning:To make sure that the quality of concrete is good during casting concrete, the bored hole must be cleaned one more time.

New

Mud sedimentation

90m3/h, H=100mSlim Pump 22KW

BentoniteReturn Mud screenMud and Bentonite

11. Casting concrete:- After finishing second cleaning, we will take a sample of bentonite at the bottom of bored hole and this sample will be inspected by Engineer and inspector.- During casting concrete, the tip of tremie pipe will always be under concrete surface at least 2.ometter.

12. Removal of casing:After finishing to cast concrete, casing will be removed from bored hole and 2 hours later the bored hole will be back filled by sand or soil.

Concrete