2.Method Statement of Bored Pile - Eng

Method Statement of Bored Pile ConstructionAppendix 2: Equipment and manpower Appendix 3: Plan of drawing construction method of bored pile Appendix 4: Sequence of construction bored pil

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Method Statement of Bored Pile Construction

CONTENTS

1) Standards related 2

2) Pile works 2

2 Work Quantity 3

3 Construction Schedule 4

4 Construction team 4

5 Site Organization Chart 4

6 Equipment and Manpower 4

7 Material list 4

8 Overall Construction Sequence 5

1) Work flow-chart 5

2) Bored pile construction works 7

9 Method Proposed to Mix, Supplying and Recycling Bentonite 21

1) General Requirements 21

2) Detail of Method to mix Bentonite Suspension 22

3) Supplying and Recycling of Bentonite Suspension 23

10 Construction Schedule 23

11 Safety Control 23

1) Provisions for Workmen 23

2) Provisions for equipment, plant, machine 24

3) For bored drilling works 24

4) Table of hazard assessment 25

12 Environmental Control 25

13 Quantity Control 26

1) Bentonite mud testing 26

2) Slurry testing 26

3) Concrete testing 26

14 Emergence Response Chart 28

Appendix :

Appendix 1: Site Organization Chart

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Appendix 2: Equipment and manpower

Appendix 3: Plan of drawing construction method of bored pile

Appendix 4: Sequence of construction bored pile

Appendix 5: Drawing of construction method for bored pile

Appendix 6: Construction schedule for 1 pile

Appendix 7: Inspection and test plan

Appendix 8: Safety work proceduce manual

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1 General

This method statement describes the procedure and the quantity control for construction of boredpile d=1.2m The drilling method will be apply the earth drilling method The method consist ofthe content as following:

- Work Quantity

- Site Organization Chart

- Material List

- Equipment and Manpower

- Overall Construction Sequence

- Quantity Control

- Safety & Environmental Control

The method statement for the construction bored pile (D=1.0m) shall be submitted separately.The method statement for the static load test, PDA test, sonic pulse test and other tests forbored pile shall be submitted separately

Construction and Measurement of Bored PilesBored Piles – Determination of identify of concrete –Pulsed ultrasonic method

Bored Piles – Method of detection of defects by lowstrain dynamic test

Material for the pipes Standard penetration test (SPT)Construction shall follow Technical specification and approved working drawing

Number

Of pile

Total Length (m)

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- Team no.1 – 422 Company: From A1 to P5;

- Team no.2 – Sub Contractor no.1: From P6 to P8;

- Team no.3 – 407 Company: From P16 to P22;

- Team no.9 – Sub Contractor no.2: From P59 to P60

5 Site Organization Chart

Please see appendix No.1

6 Equipment and Manpower

Please see appendix No.2

7 Material list

List of required the approved major materials is shown below:

1 Steel Rebar

TCVN 1651 : 2008TCVN 197 : 2002TCVN 198 : 2008

Fy =400 Mpa

2 Concrete S10.07-TCKT Specification Y-30 Mpa

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Dout=113.5mmt=3.5mm

Dout=59.9mmT=3.0mm

4 Cement mortar for

fillup sonic pipe TCVN 9396 : 2012 30 Mpa

8 Overall Construction Sequence

1) Work flow-chart

The work sequence is presented in the Flow-Chart as follows:

Inspection:

← - Check point

← - Check vertical of casing

← - Elevation of top casing

- Check to vertically kelly bar

- Property of bentonite,

- Depth of bored hole,

- Characteristics of the soil

- Diammeter of bored hole

- Vertical of bored hole (Koden machine)

Set up electric line and water line

Step 2

MobilizeTime excavator

50T Crane, drilling equipment

Chipping equipment

Assembly crane boom

Mobi tank and setting

Casing, bending, cutting machine and setting

Re-bar, sleeper, bentonite powder

No.2 Pile pre-drilling and installing casing for accumulation bentonite

No.1 drilling, checking bored hole, cleaning bored hole 1st time, installing rebar cage, cleaning bored hole 2nd

Step 3

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Casting concrete and remove casing

Step 7

Construction final pile

Setting casing at near final pile for accumulation bentonite

Drilling, checking bored hole, cleaning bored hole 1st time, installing rebar cage, cleaning bored hole 2nd time Casting concrete and remove casing

Cleaning inside of bentonite casing and extract that casing

Step 8

For the next pier

Re – arragement bentonite facilities and rebar yard

Re – location bentonite facilities (follow the water supply system)

Construction all pile by same methodMoving to next Island (Use Bubber plate)

Cleaning inside of bentonite casing and extract that casing

+ Moving bentonite facilities, re-bar yard

- Decide length of pile with soil condition bearing

Inspection:

← - Check point

- Decide length of pile with soil condition bearing

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2) Bored pile construction works

Step 1 : Make fence for keep working area and traffic control

Step 2 : Set up electric line and water line

Step 3 : Demolish and removing

+ Center medion strip, lighting pole …

+ Set up wasing facility

Step 4 : Mobilize

1 Time excavator

2 50T Crane, drilling equipment

3 Chipping equipment

4 Assembly crane boom

5 Mobi tank and setting

6 Casing, bending, cutting machine and setting

7 Re-bar, sleeper, bentonite powder

Step 5 : Start drilling (for 1st pile)

1 No.1 pile pre-drilling and installing casing

 Locating center point of the bored Pile

The transeverse line setting out:

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Center point of Bored pile

The center point of the pile shall be surveyer and marked by suitable stakes After setting

of the casing this center point shall be re-checked to confirm the accuracy Anycoordinate of pile shall be submitted to the Engineer to get approval

The center point of pile will be marked as specified in the Drawings

Reference marks will be established for determination of pile center line duringconstruction The center of the pile shall be surveyed and inspected by Engineer

 Pre-drilling

Base Machine to be set upon the pile center horizontally and vertically

The centering of the machine is to be made by the tip of Kelly bar to be position on thepile center and examine the horizontal of the machine and the verticality of the Kelly bar.These examinations are to be made by a water level equipped in the machine and byplumb

To protect the upper part of hole, a temporary Casing pipe to be installed

For this purpose, pre-drilling is to be made by Earth drill

 Installing Casing Pipe

Bored pile construction will commence from setting out pile location, the contractor willinstall temporary casing by crane with Vibro Hammer

Before installation, the casing shall be free from significant distortion They shall haveuniform cross-section throughout each continuous length

The casing will be set at the exact point by total station and plumb as below:

Guide frame Plumb

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Method Statement of Bored Pile ConstructionThe diameter and thickness of casing shall be considered for such calculation Totalstation setting up in the site will be maintained to check the verticality of pile untillcompletion of drilling bored hole.

Using the vibratory hammer to drive the casing, as below:

- Using Drilling machine to make a hole with 1m depth Next, Crane will load ofcasing and put in bored hole so that exacting center point

- Using Vibration hammer to clamp the casing and starting to make vibration on point ofcasing top in turning circle, then vibrato hammer will be used to install the casingcontinuously to reach the designed level

- During driving of the casing, its location and verticality will be checked by the totalstation and plumb

- Elevation of top casing higher than 0.5m of ground level

- Temporary casing after installation shall be checked for elevation and position with therequirement in S10.07(5) “position tolerance” (Section g):

- Casing for drilling shall be fixed with steel cage

+ The centre of the casing shall not deviate more than the minimum (D/6=200mm;100mm) from the theoretically center correct position shown on the Drawings

Casing Vibrating hammer 60KW

2 No.2 Pile pre-drilling and installing casing for accumulation bentonite

3 No.1 drilling, checking bored hole, cleaning bored hole 1st time, installing rebar cage,cleaning bored hole 2nd time Casting concrete and remove casing

 Preparation of bentonite Liquid

The facility for circulation of bentonite liquid shall be set up as below

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Method Statement of Bored Pile ConstructionRestoring bentonite mud from bored hole

Providing bentonite into the bored hole

2

Bored hole Dimension 6x2.3x2.2

1

Pump

4 Water tank

Water tank Desander

Pump

Mixer

Bom Pump

3 Pump

Mixer

4

Dimension 6x2.3x2.2 Dimension 6x2.3x2.2 Dimension 6x2.3x2.2

Sandbox

Statistics table specifications of bentonite tank:

Drilling Drilling Cleaning1st Cleaning2nd

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hole)

(Bottom

of boredhole)

(Bottom

of boredhole)

Circulation tank for bentonite liquid shall be checked timely during piling work andprecipitated material in tank such as sand or mud shall be removed adequately

Water used for mixing bentonite is potable water (well water) in accordance withstandards TCVN 4506 :2012

When the bucket is lifted up, the bucket is to be rotated reversibly to release from thebottom and to be lifted up slowly to protect the hole from collapse by piston effect Thecontrol of verticality during drilling work shall be made by plumb with string or theodolitesfrom two directions in 90 degree

Contractor will monitor bentonite suspension properties during the construction period toprevent it from being over flown to the site and the neighborhood In process drilling, toavoid the overflow of betonite, building brick wall after installing fence

Excavated soil shall be continuously investigated by eye checking to compare with thegeological data during drilling time

If there is any discrepancy between excavated soil and geological data during excavation,the Construction shall report it to the Engineer

During boring, vertical alignment of the drill rod shall be checked

Soil sampling is taken at the beginning and end of any soil layer and each 2m

In case of stop working for a long period, bucket shall be placed outside of bore hole

In process of drilling, the contractor will arrange two plumps in two vertical directions andalways appearing worker to check the vertical of Kelly bar

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kelly bar

Casing

Bottom EL

Supplying betonite liquid

Bentonite liquid

The contractor shall use dredge humus Bucket which has the shape of toe bucket likedrilling bucket to dredge the disturb soil and moving of tremie pipe during clearing byreverse circulation method to clean the disturbed soil

 Construction tolerance:

The following construction tolerances shall be maintained in constructing drilled shaft:

- The center of the completed pile at the cut off level shall not deviate more than min D/6

=200mm or 100mm from the theoretically correct position shown on the Drawings

- The inclination of the pile shall not deviate more than 1:100 from the required vertical alignment

- The Engineer will confirm the final pile toe level after his inspection of the earth layers penetrated by the pile

 Inspection

Checking bentonite solution before placing concrete

Any method and the equipment shall meet all safety requirements

Check vertically of Kelly bar by plumb and check vertically of bore hole by koden machineClean and Clear the site

 Problem – solving when drilling :

- When drilling hole wall is collapsed, it is require to find out the reason and location of collapse for appropriate counter measures

- If the wall of drilling hole is substantially collapsed, earth filling will be required to the collapsed location, check and change the technical criteria of bentonite solution, stop the drilling work for a while, find out the reasons and take treatment measures prior to restarting the drilling work

- If bored hole is inclined, curved, hang drilling auger at curved position to re-drill until theverticality is reached If it is extremely inclined, use clay to refill and wait until soil is consolidated then restart the drilling

- When drilling hole loss bentonite and height of solution column is decreased, it is required to deepen casing, compact soil surrounding pipe casing, make bentonite

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Method Statement of Bored Pile Constructionmortar more solid, add clay into drilling hole and then control drilling gause or drilling auger slower to seal all bentonite leaks.

- If the drilling auger is fallen in bored hole, use wire, hook to pull it out In any case, it is strictly prohibited to allow worker to dive to solve the problems in bored hole

3.2 Method of confirmation the verticality of bore hole

After drilling completed, Koden test will be carried out under the supervision of theContractor, the Engineer To check the bored hole verticality and shape to ensures thatthe deviation is less than the tolerance of project specification

The steps are as follows:

- Checking bore hole and bentonite slurry before to Koden test;

- Install Koden test machine by crane;

- Input the parameters of bore hole;

- Place the winch unit over the top of drilled hole or on the steel casing Position the sensor at the center of the hole;

- Lower the sensor into bentonite slurry Hole the sensor at depth approximately 1.00 to 1.50m for initial calibration;

- After calibrations, restore the sensor to the starting position and perform the test The tests are carried out in downward monitoring and upward monitoring Drill hole profile along 2 perpendicular axes are printed out immediately

In case the inclination of borehole exceeds the allowed criteria, then we drill by reamingthe bored hole side to obtain the verticality of borehole

In case, height of sediment at bottom of bored hole is more than 2m, contractor should usecleaning Bucket to take out it before carrying out clean bore hole

 Cleaning by submerged pump

Replacing bentonite inside boring holes by new bentonite with higher quality Submergedpump shall be fixed with tremie pipe in location from the ground at least 15-20m and thenbentonite shall be pumped to the tank During pumping bentonite circulated continuously.Debris, mud, sand… that pumped out of the bored hole shall be disposed to the hole andre-treated by sand filtering rig for the re-use

In case of Submerged pump capacity is not enough, additional pump will be set at the top

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