Bored pile technique

Tools & Materials

Stan da rd too ls a nd a ccessories

Sling rope spike Reaction bracket Remote control box Inclinometer Hydraulic hose Power pack Sight level gauge Rotator

Op tio n all ex tra to o ls /m a te ria ls Op a b1

e a






g h f

a. Main chuck collar b. Step c. Sub chuck d. Sub chuck collar e. Counterweight f. Base frame g. Reaction arm h. Radio control box j. Operator house k. Computer monitor/recorder

Counterweight - Drivinf force

Driving forceF = A partial weight of rotator W1 + Weight of casing W2 + Thrust cylinder force P ­ Skin friction force R Cylinder forceP + Lower frame may be lifted up


W1 W4Counterweight

Model RT150A RT200A RT300


W1 17t 25t 35t

Suitable mass W4

RT150A......... 3 ~ 5 t x 2 pcs RT200A......... 5 ~ 10 t x 2 pcs RT300 ........... 7 ~ 15 t x 2 pcs




Too large driving force P (Pushing down force of thrust cylinder ) brings the lower frame of the rotator to be lifted. A suitable mass of counterweights are needed to stable the rotator while applying a torque and a driving force to the casing.

Effect of SUB CHUCK

Main chuck Sub c huck

Effect of sub chuck -To prevent the casing from unexpected dropping when main chuck is opened. -To prevent the casing from inclining when main chuck is opened. -To assist the crawler crane when the casing is suspended by it.

Sub chuck is effective to maintain a high degree of vertical accuracy of the casing

nk that the casing is always influenced by unexpected side force from soil, boulders, etc which makes the casing to incline when the in chuck is opened and the casing is freestanding in the bore hole. If the sub chuck holds the casing before main chuck opened, the sing can be maintained at vertical state against any side force.

Base frame on soft surface

Lower frame H-beam frame Leveling jack

Proper stopper position Improper stopper position Base frame

A suitable base frame is effective to maintain the rotator stable if the installation surface is soft. Provide suitable stoppers on the base frame to counter the torque reaction force. Do not provide the stopper against the leveling jack float to prevent fixing bolts of the jack from loosening.

Torque reaction force countering arm ... .improper way

Ca s tow in g t ard end this s to d ir b e i ect n io n cli ne d

The r eact i on ar m i s equal t o a cant i l ever so t hat t he casi ng i s i ncl i ned t owar d t he di r ecti on of t he ar r ow when r ecei vi ng a r eact i on f or ce of t he t or que.

Reaction arm

I ncl i ned casi ng br i ngs about a hi gh ski n f r i ct i on f or ce

When receiving a torque reaction force with a reaction arm (Cantilever), the casing tends to be inclined which causes the skin friction

Assistant crane

Model RT-150A, (L) RT-200A RT-300

Pile diameter 1000 ~ 1500 1500 ~ 2000 2500 ~ 3000 Crawler crane Line pull Crane capacity t 50 ~ 70t 26t x 6m 65 ~ 80t 32-34t x 6.5m 100t more 57-59t x 7m

Casing- part name

Casing cap Casing section First casing Cutting bit key Lock bolt Sling rope

Casing construction

Double wall Nominal length: + 300mm




Single wall




Required casing leng th: Drilling depth

Cu ttin g b it

First casing

(Tu n g s ten carb id e tip )

10mm 10mm


Outer Center Inner bit bit bit

Three types as Outer, Center and Inner cutting bits are available. Generally, Outer and Inner cutting bits are arranged at the distance of 180mm to 200mm in pitch. The center cutting bit is provided when drilling into hard bed rock.

Arrangement of cutting bits

Rotation direction

Relation to soil condition

Common soil4°10mm

Large boulder, concrete base, weathered rock

Slightly weathered rock, Fresh rock bed

Outer cutter,

Center cutter

Inner cutter

W ea r lim it o f cutting b it

Recommended wear limit Breakage by overload

New bit

Normal wear

Model of cutting bit

(In case of clockwise direction Size/ Maker Width SUMITOMO TOHO CDSR40I CDSR40C CDSR40O CH40S CDSR50I CDSR50C CDSR50O CH50S Outer DCS-M40KR 40mm Center DCS-CM40K Inner Bit holder Width Outer 50mm Center Inner Bit holder DCS-CM40L HLDM40 DCS-IN50KR DCS-CIN50K DCS-IN50KL HLDIN50

Caution; Contact us when cutting hard boulders, bed rocks or underground obstacles.


14 pages

Report File (DMCA)

Our content is added by our users. We aim to remove reported files within 1 working day. Please use this link to notify us:

Report this file as copyright or inappropriate