Tidal Flood Defences River Arun - ArcelorMittal Piling · Tidal Flood Defences River Arun...
Transcript of Tidal Flood Defences River Arun - ArcelorMittal Piling · Tidal Flood Defences River Arun...
Existing steps to be broken Voids filled with
Class 1A or 1B fill
Class 1A or 1B fill
Class 6A modified fill
Future ground level
Existing structure Sand
Chalk
Fill
Wall typically HZ 1180M D-sol.12 king piles and AZ 26 sheet piles infills
Flood protectionlevel
Riverward Landward
MHWN +1.35 m0D
+5.0 m
+4.25 m
MSL +0.05 m0D
MLWN -1.35 m0D
MHWS +2.85 m0D
HAT +3.45 m0D
-0.45
TGL 3.725
+4.80 mFuture ground level
+0.02
MLWS -2.65 m0D
LAT -3.25 m0D
750
670
==
Class 1A or 1B fill
Working in partnership with Arun District Council, West Sussex Council and Littlehampton Harbour Board, the Environment Agency is improving the tidal flood defences along the East Bank of the River Arun in Littlehampton, on the South Coast of England. The work is being carried out by VolkerStevin and CH2M Hill and is budgeted at £14.1million.
Completed at the end of 2014, the scheme protects 2,000 residential properties and businesses against 75 years of predicted sea level rise as well as enhancing the riverside walkway between the town and the beach.
Two types of retaining wall were considered for the structure which has to withhold upto 6.9 m soil and ground water without lateral support. Initially a tubular wall in combination with AZ® steel sheet piles was thought to be the most economical but on consideration of the long design life, the HZ® / AZ® combined wall system from ArcelorMittal was found to be the most economic and technically feasible solution.
It utilises large HZ®-M (HZ 1180M A-sol.12 & HZ 1180M D-sol.12) beams with welded interlocks, which are installed by panel driving techniques down to the required levels before AZ 26 sheet piles are driven to connect the beams into a continuous wall. The beams carry the vast majority of the bending moments and have the advantage that the face of the beam is small in comparison with a tubular solution.
CH2M Hill had to take great care over assessing the design life of the structure, which at its most aggressive depth had to tolerate up to 7.2 mm thickness loss through the design life of the flood wall.
Tidal Flood Defences River Arun Littlehampton | UK
Typical cross section
Tidal Flood Defences River Arun Littlehampton | UK
Project Owner Environment Agency
Design Consultant CH2M HILL
Contractor VolkerStevin
Sheet Piles HZ 1180M A-sol.12 21.2 m S 355 GP 1 031 t AZ 26 Pairs 12.6 m S 355 GP 233 t HZ 1180M D-sol.12 21.7~22.0 m S 430 GP 971 t AZ 26 Pairs 12.2~12.6 m S 430 GP 222 t Total 2 457 tonnes of sheet piles
Photography copyright © High Camera Ltd | UK _ www.highcamera.co.uk
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ArcelorMittal Commercial RPS S.à r.l.Sheet Piling | 66, rue de LuxembourgL-4221 Esch-sur-Alzette | LuxembourgT (+352) 5313 [email protected]
ArcelorMittal Commercial UK LtdSheet Piling | Flr 3, Fore 2, Huskisson WaySolihull B90 4SS | United Kingdom T (+44) 0121 713 6655 | F (+44) 0121 733 1299 sheetpiling-rps.uk@arcelormittal.comsheetpiling.arcelormittal.com
MLW
Shelter
COASTGUARD ROAD
Shingle
Mean H
igh
River Arun
Lighthouse
ARU
N PAR
ADE
Park
Sand
4.0mStone
(occulting white)
East Pier
Stone
Amusement Park
MLW
Amusement
Sand and Shingle
Mean Low
Water
Shingle
NN
B463457/CIVIL/103
B463457/CIVIL/103
C463457/CIVIL/103
C463457/CIVIL/103
A463457/CIVIL/103
A463457/CIVIL/103
A463457/CIVIL/103
A463457/CIVIL/103
H463457/CIVIL/103
H463457/CIVIL/103
J463457/C
IVIL/106
J463457/C
IVIL/106
M463457/C
IVIL/107
M463457/C
IVIL/107
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MR
L
L
MR
X
X
ARU
N PAR
ADE
Promenade retaining wall
Exclusion zone forFoul Water Crossing
Steel sheet piles withreinforced concrete cap
REACH 2
Steel sheet piling
REACH 2 Steel sheet piling
REACH 1 Steel sheet piling
Promenade retaining wall
Reach 1 and 2 General Arrangement
HZ®-M template
When analysing the two solutions the HZ® / AZ® was found to be stronger after sacrificial losses in comparison with the same losses from the tubular solution. This resulted in the significant cost saving by utilising the HZ® / AZ® solution.
All of the solutions were analysed and priced with ArcelorMittal included as part of the project team with the “Early Supplier Involvement” service.
Soils typically consisted of made ground with overlying chalk of varying strength. The made ground was the result of previous port construction (and activity) and was very varied. It included obstructions and cobbles. The chalk was weak in the upper layers, but increased in strength with depth and had flints and cobbles within the matrix.
The installation was carried out by VolkerStevin. Very robust driving frames have been constructed such, that the lower frame was close to high tide level and then the wall was installed with a combination of vibratory techniques (PVE 40VN) and noise shrouded percussive techniques (BSP CX85 in 7 Tonne mode and BSP CX110 in 9 Tonne mode). All equipement was heavily shrouded with double skin acoustic shrouding to keep noise levels to a minimum.
The site worked through some very difficult conditions with the wettest winter for some years, in conjunction with long periods of gale force winds. The installation works on Reaches 1 & 2 have been successfully completed with piling work moving to higher reaches using conventional AZ® sheet pile walls.