Safe Construction of Bored Piling Work with Use of Casing

Safe Construction of Bored Piling Work with Use of Casing Oscillator

Ir. Terence Ng Senior Project Manager

1. Review of Typical Bored Pile Construction 2. Recent Use of Under- Reamer in Bored Pile Construction 3. Common Use of Casing Oscillator 4. Establishment of Operation Manual for Casing Oscillator Operator 5. Casing Oscillator Operation Improvements

i) Safe Access to Working Platform ii) Color Coding System on Control Panel iii) Checking System (TCPs & Point and Calling System) iv) Safety Enhancement for Safe Operation of Casing Oscillator

Proper Use of Power Pack Triangular Wedge

6. Further Safety Measures for Working on RCD Platform 7. Safety Training for Operators and Supervisory staffs 8. Q & A

Content

1. Review of Typical Bored Pile Construction

Q: How did we overcome underground obstruction in

the past?

1. Review of Typical Bored Pile Construction i) Rock Chisel to Break the Obstruction, then Drive the Casing Down by Oscillator

Drawback: Large Vibration

Not suitable for piles close to

1. Existing Old Buildings 2. Slopes 3. Retaining Structures

2. Recent Use of Under-Reamer in Bored Pile Construction

Under-Reamer to overcome underground obstruction, then drive the casing down to 500mm into the rockhead.

Benefit: Less Vibration



Oscillator

Reverse Circulation Drill (RCD)

Temporary Steel Casing

3. Common Use of Casing Oscillator

3. Common Use of Casing Oscillator

Is it a safe access to ingress and egress from the working

platform ?

Are there any Operating Procedures or Checking

System for Casing Oscillator ?

Are control levers and pressure gauges

often confusing to the Operator ?

4. Establishment of Operation Manual for Casing Oscillator Operator

操作指引 1.每日開機前，檢測油水及必要時補充足夠油水。每天工作都必須全機唧油(包括各活動較及各牛眼)。

2.機座必須四平八穩地開樁，不可隨便。若發覺機底塌坭引起傾側，必須即時補救，否則毫無進度及損壞磨樁機。

3.使用左、右升降桿(Lifting)來控制樁通升降及留意升降唧油壓錶壓力。落通時，壓力不要過大，否則升通困難。

• 深通時起步須緩慢。 • 落通盡量垂直，避免擺幅過大。可使用調節桿(Adjusting)來調控樁通垂直度。

4.使用推磨桿(Oscillating)來推磨樁通及留意推磨唧油壓錶壓力。推磨時，壓力應為200-230bar之間。


操作指引 5. 追通速度應以地質堅實程度為依據。謹記留意升降唧油壓錶和推磨唧油壓錶油

壓錶。

• 鬆軟可快，堅實則慢。 • 使用上乸控掣桿(Clamping)和下乸控掣桿(Retaining)依次序鎖固樁通及

留意上乸油壓錶和下乸油壓錶。 • 追通基本操作次序： a) 先鎖緊下乸後，再提高升降唧至高位，然後鎖上乸來固定樁通，再留意

上、下乸油壓錶是否正常 b) 推磨樁通時，先放鬆下乸，穩定地降低升降唧至底位，然後鎖下乸，再

留意上、下乸油壓錶是否正常 c) 確定鎖固樁通後，先放上乸再一次提高升降唧至高位，然後重複次序1-

3（返手），直到樁通到達指定深度 • 起通時，次序同追通大同小異，只需要把升降次序相反就可。 • 謹記任何升降動作都需要鎖上乸，再用升降唧來控制樁通上落。 • 上、下乸工作壓力應為200-230bar之間。如發現壓力不能維持，就立即通

知機工維修 • 磨樁機吊離樁通後立即檢查上、下乸壓板是否需要維修。 • 磨樁機整體打油一次。


操作指引 6. 駁通時，先把樁通推磨至最低點，然後鎖固上下乸和留意上下乸油壓錶是否正常，再駁長樁通，繼續追通。 7. 當樁通到達石層時，忌強力切削堅硬石層。應先通知上級，再由上級安排開鎚或使用逆流鑽機。 8. 如樁通到達指定石層需使用逆流鑽機，在安裝逆流鑽機前應注意事項：

•記錄樁通之長度。 •確保樁通垂直。 •磨樁機吊離樁通後立即檢查上、下乸壓板是否需要維修。 •磨樁機整體打油一次。


操作指引 9. 如樁通未達指定石層需使用逆流鑽機進行擴大吼時，在安裝逆流鑽機前應注意

事項：

一. 記錄用逆流鑽機之編號、樁通及鑽頭鑽桿之長度。二. 確保樁通垂直。三. 清洗上、下乸壓板，盡量將沙石清走。四. 先鎖上乸，再放鬆，重複程序兩次，最後鎖上乸至正常鎖固油壓以確保樁通完全鎖

定(三前二後法)。留意上乸油壓錶需達200bar或以上。五. 再鎖下乸至正常鎖固油壓作輔助鎖固。留意下乸油壓錶需達200bar或以上。謹記切

勿單靠下乸來鎖固樁通六. 檢查上、下乸的鎖固油壓是否正常穩定，再上磨樁機工作台檢測上、下乸是否緊貼

樁通，才可以安裝逆流鑽機。如發現油壓不穩或急跌，就立即加壓。如果情況持續，就立即通知上級

七. 燒三角釜加固，以防上下乸突然出問題。(需工程師計算三角釜數量) 八. 檢查後才可安裝逆流鑽機。九. 當擴大吼完成後需要追通時要確保梯子鎖緊或吊離逆流鑽機。十. 並同鑽機手保持良好溝通，確保鑽頭放置到吼底及鎖固油壓後才可斬三角釜。十一.控制磨樁機追通時，確保逆流鑽機台面上均沒有人。十二.如需繼續擴大吼工序，應確保再燒三角釜加固及檢查上、下乸的鎖固油壓是否正常

穩定才可開動逆流鑽機。十三.並每日檢查鎖固油壓是否正常穩定。


操作時注意事項 1)密切留意樁通深度與夾出泥石料是否配合進度，舉例若夾出物料多而深度依然，則極可能是塌陷問題。

2)如樁通週邊塌陷就需要即時處理；甚者，需加分壓墊板。

3)嚴禁借外力推磨樁通或修正樁通垂直度。若用吊機行前或行後，企圖修正樁通，將會損毀磨樁機若在樁通上強加重物，企圖令樁通較快進入地層，將引起樁通變形

4)升降去盡，將令牛眼爆裂，唧筒損壞。

5)推磨扯盡，將令唧筒折斷，推拉力大降。

6)與吊機機手密切配合。何時用夾，何時用鎚，偏左或偏右施鎚，壓通或升通，互相知會。

7)視機如己物，保持機身整潔，及時清理石矢濺附物或泥漿。

8)磨樁機手須留意控掣桿及相關油壓錶的顏色碼系統，切實觀測每次加壓均己逹到所須的操作壓力。



5. Casing Oscillator Operation Improvements i) Safe Access to Working Platform of Casing Oscillator

ii) Color Coding System on Control Panel 5. Casing Oscillator Operation Improvements

iii) Checking System (TCPs) Deploy technically competent person(s) of

T1/T4 to check the daily checklist to ensure safe operation of Oscillator.

5. Casing Oscillator Operation Improvements

iii) Checking System – Pointing and Calling System 5. Casing Oscillator Operation Improvements

iii) Checking System - “Pointing and Calling” system


1. The upper clamp and the lower clamp of the Casing Oscillator shall be pressurized prior to addition of loading on the steel casing, when the toe of steel casing does not rest on in-situ soil and/or rock.

2. The power pack of the Casing Oscillator shall be connected to the control

panel prior to addition of loading on the steel casing, when the toe of steel casing does not rest on in-situ soil and/or rock.

3. For long periods of leaving the Casing Oscillator unattended, before starting work, both upper and lower clamp of the hydraulic cylinders are recommended to re-pressurized so as to ensure the steel casing is firmly and properly clamped and held.

4. Both the upper clamp and the lower clamp shall be re-pressurized prior to switching off of power pack.

iv) Safety Enhancement for Safe Operation of the Casing Oscillator

Proper Use of Power Pack


In case the toe of steel casing does not rest on in-situ soil and/or rock during reaming process, prior to application of additional loading on the steel casing, 4 triangular wedges shall be welded temporary casing at a level above the top of Casing Oscillator to prevent the casing from slipping downward.

iv) Safety Enhancement for Safe Operation of the Casing Oscillator

Triangular Wedge


6. Further Safety Measures for Working on RCD Platform

In the situation where the toe of steel casing does not rest on in-situ soil and/or rock, all persons working on the folding gate at RCD platform must wear safety harness & attach it to the independent lifeline suspended from the portal frame of the RCD.

7. Safety Training for Operators and Supervisory Staffs

7. Safety Training for Operators and Supervisory Staffs

Q & A

Documents

Safe Construction of Bored Piling Work with Use of Casing