What is a RCD? (Reverse Circulation Drill)
Reverse Circulation Drilling (RCD) system, also known as air-lift is that compressed air is injected into the drill pipe below water level just above the drill bit. This reduces the density of internal water column and starts circulation. The mixture of water, air and cuttings are then flushed out through the drill pipe into the settling tanks
BUMA drilling systems are designed to maximize production rates through hard rock. Productive drilling occurs when the majority of the time spent on-site is devoted to actually drilling and not in machine set up. BUMA RCD’s do just that.
BUMA ‘Reverse Circulation’ drilling involves the supply of air down through the drill-string to decrease the ‘effective density’ of the water in the centre of the drill-string. Operating much like an ‘air-lift’, the drilling spoils are carried out of the hole through this rising column lower-density air/water mixture (see Figure). Reverse Circulation requires that the outer annular area of the casing be kept full of water in order to provide the hydraulic head required to effectively ‘push’ the central column of air/water/spoils up and out of the hole through the central pipe of the drill-string.
Most common applications of RCD
· Rock drilling
· Rock socketing
· Underreaming
· Bell-out of the rock socket
· Pile cutting
· Milling of deformed casings
· Anchor drilling
· Secant wall drilling
Reverse Circulation is an effective drilling technique for a wide range of pile diameters including very large piles of even 3m diameter and larger. It is also effective for very deep holes, and holes drilled into hard-rock. Working with RCD Rigs is highly efficient, safe and environmentally friendly solution for drilling large diameters and depths. If you fall into one of the following conditions, RCD is the best Solution to deal with it.
1) Large Diameter (Larger than 800 mm)
2) Deep Depth (Deeper than 50 m)
3) Hard Rock Drilling ( ~ 350 MPa)
4) Bore Piling in Marine Condition.
Reverse Circulation is able to control/direct the drilling spoils by simply directing the discharge pipe to the desired site location or even to a dedicated barge (for environmentally sensitive, overwater applications). This cannot be accomplished with direct circulation which allows water and cuttings to spill out of the top of the pile.
BUMA RCD drills represent the most ruggedly designed and extensively field-tested all-purpose drills in the foundation industry. BUMA is known for Reliable & Powerful RCD’s most suitable for large dia Rock drilling for Marine structures viz jetties, berths, dry docks, bridges & piers. There is simply no better choice for foundation contractors than a BUMA Reverse Circulation drill.
BUMA RCD’s have been successfully used at Bandra-Worli Sea Link, Mumbai Trans-Harbour Link and currently being used on Versova Bandra Sea Link.
MTHL: Daewoo-TPL JV, has successfully used BUMA RCD’s in MTHL project. The piling job completed last year and DAEWOO –TPL has done 840 nos. of 2m dia piles using 6 BUMA RCD’s. Drilling depth was upto 35mtr at a drilling speed of 500mm per hour. Also, for the first time in India, 3m dia piles successfully completed using a RCD in INDIA. This was achieved using BUMA RCD model BM 3030. 8 nos piles having depth of 30m completed successfully at a drilling rate of 400mm per hour.
In terms of the deepest drilling depths in BUMA records, some examples are: The deepest drilling depth recorded in South Korea was during the construction of Incheon Bridge, reaching 80 meters. In the United States, the KYTC Kennedy Mill Bridge Replacement project achieved a drilling depth of 90 meters. Lastly, for the Hong Kong project, the excavation reached a depth of 127 meters.
On The Greater Male’ Connectivity — Male’ to Thilafushi Link Project in Maldives, AFCONS has immense pleasure to inform that their team has successfully completed concreting of one of the deepest piles in the Project which was bored using BUMA RCD. Afcons is also confident of it being the World’s deepest cast-in-situ Pile Foundation.
#BUMA is known for Reliable & Powerful #RCD for large dia drilling for Marine structures-jetties, berths, dry docks, bridges & piers. Backed by unmatched SURETECH SUPPORT.
Call #FoundationSpecialists 1800 120 7873 sales@suretech.co.in www.suretech.co.in #SuretechInfra #marinejobs
