PS MS CISCP a1 EN(BAUER)

This method statement contains Bored Pile Work drilling~ reinforcement~ casting concrete, PileHead Treatment and Grouting Sonic Tube, except the description of Sonic Test and Static Load

1 General - 3

2 Quantity of Work - 3

3 Schedule of Work - 4

4 Site Organization - 4

5 Equipment and Workforce - 6

5.1 Bored Pile Work - 6

5.2 Grouting Sonic Tube - 7

5.3 Pile Head Treatment - 8

6 Materials - 9

6.1 Bored Pile Work - 9

6.2 Grouting Sonic Tube - 9

7 Construction Procedure 7.1 Bored Pile Work - 10

7.2 Grouting Sonic Tube - 26

7.3 Pile Head Treatment - 27

8 Quality Control - 28

9 Safety Control - 28

10 Environmental Control - 29

Appendixes

1 Construction Schedule -03 pages (A4 size)

2 Drawing of Hanging Bar - 01 page (A3 size)

3 Inspection and Testing Plan -03 pages (A4 size)

(Total 70 pages)

1 General

This method statement describes the construction procedure and quality control aspects of Place Concrete Pile construction in accordance with General Specifications section 06210

Cast-In-Proposal of sub-contractor will be submitted separately

The working drawing will be submitted after receipt of final design of Bored Pile such as lengthand location of pile

This method statement contains Bored Pile Work (drilling~ reinforcement~ casting concrete), PileHead Treatment and Grouting Sonic Tube, except the description of Sonic Test and Static LoadTest

Total Concrete Volume (m3)

Total Re-bar Quantity (Ton)

Project Manager

Site Manager

Site EngineerForemenOperator

5 Equipment and Workforce

5.1 Bored Pile Work

The list of equipment and worker for a typical working party for Bored Pile Work is shownbelow Plural working parties will be provided to work at several locations simultaneously Detail

of equipment and workers should be submitted separately in order to check and approve by theEngineer before commencement of bored piling work And they shall be inspected by theEngineer in accordance with Guide Form No BBMMNL.(Apendix -4)

Table 5.1 List of Equipment for Bored Pile Work

1 Drilling Machine(Base Machine) Crawler TypeMax Drilling Depth 61 m

Max dia 2.0m 1 no. Equivalent Bauer – BG25

2 Service Crane 40t class crawlerBoom Length 31 m 1 no

3 Hydraulic Excavator 0.4~0.7 m3 Excavator 1 no

5 Mud Screen 4-6 inches 7.5 KW 1 no for cleaning bentonite liquid

11 Air Compressor pressure 7kgf/cm2 1 no

12 Tremie pipe 10 inches - total 57m 1 set Depend on bored pile length

15 Steel Casing Pipe D=1100mm 2 each Length =6.0m

No Item Description Qty Remarks

20 Concrete Hopper 1.0 m3 1 no if required for casting concrete depending on the site condition

21 Dump Truck 10~15t 3 nos to transport excavated soil

23 Bentonite Liquid Sampler 1 L/S for testing bentonite

25 Funnel Viscosity Meter 1 no for testing bentonite

Table 5.2 List of Worker for Bored Pile Work

2 Skilled Worker (1) for drilling, casting, cleaning hole 10

3 Skilled Worker (2) for fabrication and installation re-bar cage 5

5.2 Grouting Sonic Tube

The list of equipment and worker for Grouting Sonic Tube is shown below The detail ofequipment and worker shall be inspected by the Engineer in accordance with Guide Form No.BBMMNL

Table 5.5 List of Equipment for Grouting Sonic Tube

2 Grout Pump 5 mpressure 5kg/cm3/hour 2 1 with 1” hose

Table 5.6 List of Worker for Grouting Sonic Tube

5.3 Pile Head Treatment

The list of equipment and worker for Pile Head Treatment is shown below The detail ofequipment and worker shall be inspected by the Engineer in accordance with Guide Form No.BBMMNL

Table 5.3 List of Equipment for Pile Head Treatment

1 Breaker 7kg ~ 20kg 5 no not fix quantity as required

Table 5.4 List of Worker for Pile Head Treatment

2 Skilled Worker for demolish concrete 10

6 Materials

6.1 Bored Pile Work

List of required material is shown below

Table 6.1 List of Material for Bored Pile Work

Reinforcing Bar CB400-V,

CB240T

Fy(min)=400Mpa,Fy(min)=240Mpa in accordance with 06400(item 2.2.1)Concrete Class Y 30Mpa in accordance with 06100(Item 2.2.2)

Proposal of Bentonite material and Steel Pipe (Sonic Tube) should be submitted separately asprocedure for material approval The bentonite suspension shall satisfy the testing criteria asspecified in General Specifications 06210, item 2.2.5 Actual ratio of bentonite mix shall besubject to final approval of the Engineer

Material stocked on site shall be kept off the ground and covered to protect from rain and dirty

6.2 Grouting Sonic Tube

List of required material is shown below

Table 6.2 List of Material for Grouting Sonic Tube

(Remarks)

For grouting, cement milk (W/C= 100%) will be used Mix proportion is as below

Cement 760kg, Water 760kg (for grout 1.0m3)

Trial mix and compressive strength test for grouting will be carried out with above proportionunder inspection of the Engineer And report will be submitted to the Engineer for approval beforecommencement of grouting work

7 Construction Procedure

7.1 Bored Pile Work

7.1.1 Work Flow of Bored Pile Work

7.1.2 Description of Work Sequence for Bored Pile Work

(*) Trial pile and static load test

According to General Specification section 06210, Item 3.6.4 and 3.6.9 Trial pile is separatefrom the bridge foundation, and is installed and tested prior to commencement of construction

of contract piles Sequence for construction of trial pile is the same as Sequence forconstruction of contract piles described in this document Location of trial pile shall beproposed by the Contractor and approved by the Engineer Method Statement for static loadtest of trial pile shall be made and submitted separately

(1)

Mobilization and Preparation

Prior to commencing the drilling work, all equipment and worker shall be inspected according

to Guide Form No BBMMNL with attendance of the Engineer

Any obstacles at the surface or the sub-surface of the ground are to be taken out by Excavator

or other drilling equipment

Underground water level shall be measured before piling work by temporary well or drilledhole, which shall be made temporary with adequate depth to investigate underground water If

necessary, embankment shall be applied to keep that the execution area of piling works is more

than 2.0m above underground water level.

The description of bored pile work on each structure group is as followings

Flyover Bridge : TL402,TL301, TL302B, TL302C(I), TL302C(II), ARMY, Bathien, QL2Band Bridge on land : Nguyen Tat Thanh, Interchange3(KCN Binh xuyen):

 Existing ground will be leveled for construction plan, piles on each abutment and pierwill be constructed as one construction section

Bridge crossing canal or small river: Kim Anh, Trung Kien, Dai duong, Bon, Tam long, Cam

I, Cam II:

 Existing canal will be backfilled partially or with temporary drainage pipe to keepexisting waterway in order to keep the area for bored pile work

Bridge crossing big river: Xuan Phuong, Tan loi:

 Existing river will be filled at one side with steel sheet pile or gabion as temporarycofferdam Bored piles and substructure will be constructed completely at one side.After finishing substructure at one side, temporary cofferdam and soil will be removed,river bed will be cleared for diversion of waterflow Fill other side of river with gabionand steel sheet pile as cofferdam for construction of bored pile and substructure Afterfinishing sub-structure, river bed shall be cleared as original situation

Piles at abutment A1,A2 of Kim Anh Bridge, at Abutment A2 of Dai duong Bridge, atAbutment A1, A2 of Xuan Phuong Bridge, at Abutment A1, A2 of Tan loi Bridge, atAbutment A1, A2 of Tam long Bridge will be constructed after soft soil treament nearbyabutment For these bridge, method of soft soil treament is to replace 2m or 3m of soft soilonly

Pile at Abutment A1 of Ba Thien bridge and abutment A1, A2 of TL302B bridge shall beconstructed after embankment and consolidation which residual settlement shall be less thanallowable value and approved by the Engineer to commence bored pile work Embankment

on abutment will be cut down to adequate E.L for working area of bored pile work It shall

be shown on working drawing

( 2 ) Setting O u t Pile Center

The transverse line setting out:

Pile center

Temporary mark

Reference mark

The center point of each pile shall be surveyed and marked by suitable stakes After setting

of casing this center point shall be re-checked to confirm the accuracy Any co-ordinations ofpile shall be submitted to the Engineer to get approval

Positioning shall be based on design drawings for pile layout plan and shall not deviatemore than 80mm from the theoretically correct position shown on the drawing (According

to General Specification, Section 6210 item 3.7)

Reference marks wil be established for determination of pile centerline during construction.The center of pile shall be surveyed and inspected with the Engineer’s surveyor for each pilebefore drilling

( 3 ) Setting Drilling Machine

Base machine shall be set upon the pile center horizontally and vertically Offset points forpile center shall be made at least in two directions from inspected marking of pile center Thecentering of the machine shall be confirmed by the tip of Kelly bar or bucket Horizontalsetting of machine and verticality of Kelly bar shall be checked by water level gauge orplum It is necessary to put steel plate on working ground for the foundation bed of drillingmachine to keep stability of machine and bored hole

Mark point Drilling point Kelly bar

( 4 ) Pre-drilling and Setting Casing Pipe

 To protect the top of hole, a casing pipe shall be installed after pre-drilling with depth lessthan the length of casing pipe from 0.5m to 1.0m depending on soil condition

 The purpose to use casing pipe is to protect the strata below G.L from collapse caused byheavy weight of various heavy machines and also to protect the hole from mud water on theground Inner diameter of casing pipe shall be 10~20 cm larger than designed pile diameter.Length of casing pipe shall be from 6.0m to 10m depending on soil condition Casing pipeshall be inspected with attendance of the Engineer before installation

 Top of casing pipe should be higher than working ground level at least 50cm and twosupporters at top of casing pipe should be placed firmly on steel plates

 The center of casing pipe shall be confirmed from offset marking of pile center and totalstation from construction point of survey, and its verticality shall be checked by water levelgauge After installation of casing pipe, location of center of casing pipe and verticalityshall be inspected by the Engineer’s surveyor Maximum tolerance of gradient of casingpipe is 1%

Casing pipe

Screw auger Kelly bar

Pre- Drilling Setting casing pipe

( 5 ) Drilling (up to designed depth)

Preparation of Bentonite Liquid

Bentonite shall be mixed with water by mixing machine and in proper proportion (about 80kg/m3 water) Bentonite shall be well-mixing within 10-15minutes/m3 of the mixing inorder not to be clotted and then discharging to the tank

60-The specification of bentonite shall be always checked (density, viscosity, sand content, PHvalue)

The supplying pipe and discharging pipe of bentonite shall be always checked throughout thepiling work in order to ensure that supplying of bentonite shall always maintain in soundcondition, During piling work bentonite shall be adjusted properly depending on differentstrata in order to maintain the stability of the bore-wall

Specification of Bentonite shall be as follows:

Drilling 1st

Cleaning

2ndCleaning(beforecasting)

1 Density ≤1.10 gm/ml Mud density

4 Shear strength 1.4-10 N/m2 Shearometer o

measure pipe

boredhole)

(Bottom

of boredhole)

(Bottom

of boredhole)

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

Pit for Waste Liquid

Pump

Pump

Sedimentation Tank No.2 Sedimentation Tank No.1

Used Bentinite Liquid from Bored Hole

Pump

Tank for Stock Clear Bentonite Liquid Sedimentation Tank No.4 Sedimentation

Bentonite Mixer

Clean Bentinite Liquid

to Bored Hole

Syclone Mud Screen

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

Drilling Work

Drilling work nearly up to the toe of

the casing pipe will be done without

bentonite liquid After installation of

bentonite liquid into the bored hole,

drilling work will be continued and

the top level of stabilization liquid

shall be maintained 2.0m higher than

under ground water level

When the screw auger is lifted up, the

screw auger is to be rotated reversibly

to release drilled soil and to be lifted

up slowly to protect the hole from

collapse And the screw auger shall be

put down slowly also to protect the

hole from collapse The control of

verticality during drilling work shall

be made by plumb with string or

theodolites from two directions in 90

degree During the drilling works, soil

stratum shall be monitored and

recorded carefully to check actual soil

condition under inspection of the

Engineer, and the bentonite liquid

shall be tested at least 2 times a day or

interval 4 to 6 hours under inspection

of the Engineer

When drilling into rock layer, using

screw auger sticked hard alloy

Confirmation of Bearing Layer

The confirmation of the bearing layer shall be made by the visual check of excavated soiltaken out from the bottom of bored hole under inspection of the Engineer, which is assumed

by reference of geological survey report

Surface Casing Stabilization Fluid

Screw auger

The drilling depth shall conform to the approved working drawings The bottom E.L ofbored hole shall be measured from top of casing pipe by the measuring tape with weight Theinspection of drilling depth shall be taken with attendance of the Engineer.

If actual depth of bearing layer is not corresponded to geological survey result and design ofpile, countermeasure for drilling depth shall follow to the Engineer’s instruction, such asextend excavation depth and pile length

( 6 ) Waiting for Sedimentation ~ 1 st Cleaning Bottom of Hole by Bucket

After completion of excavation of bored hole, it shall wait for sedimentation of slime for 2~3hours During waiting for sedimentation, head of bentonite liquid in casing pipe shall bemaintained to keep more than 2.0m above under ground water level Finally, thesedimentation of slime at the bottom of the bored hole shall be scraped and removed by acleaning bucket After clearing bottom, depth of bored hole shall be measured again underinspection of the Engineer

( 7 ) Fabrication of Re-bar Cage

Re-bar cage shall be fabricated in accordance with approved working drawing

The main rebar should be welded with temporary reinforcing ring bar to keep shape andstability of cage Design hoop bar shall be tied with main re-bar with iron wire

Sonic tube should be fixed by welding with temporary reinforcing ring bar at some location

At the bottom of rebar cage, sonic tube should be fixed by welding into steel plate, and steelplate is fixed by welding with rebar net at bottom of rebar cage To ensure bottom of sonictube, it will be permanently sealed and top of sonic tube shall be provided with welding steelplate to prevent the ingress of any undesirable materials Top of Sonic tube shall be higherthan temporary casing at least 30mm

Top of Sonic tube shall be extended above cut off level of pile adequately in order to carryout Sonic Test as soon as possible (7days after casting concrete) without structure excavationand pile head treatment It will be shown on working drawings (Sonic Test shall be carriedout before structure excavation and pile head treatment to avoid unsuccessfully testing due todamage of sonic tube or obstruction in sonic tube.) The sonic tube section above cut off level

of pile should be kept by temporary rebar frame in order to keep the distance between sonictubes which shall not be changed during installation of re-bar cage and placing concrete