Ras Al Khaimah Port, Phase IA, II, IA-Extension & Cantilever Wall, United Arab Emirates

Project Description

These projects have covered a timeline of 4 years ranging from 2005 to the end of 2008. All projects were carried out with the same contractor Athena SA.

Figure 1 Project Artists Initial Outlook

The Ras Al Khaimah Port development is located in Ras Al Khaimah, UAE. An existing port is to be extended by reclaiming land behind a permanent sheet pile wall. The design proposed is a main sheet pile wall tied to an anchoring wall of smaller sheet piles.
ESC proposed to use ESC cold formed fabricated sheet piles for the Main Wall and the Anchor Wall. All parameters were supplied by the client in terms of required capacity.

ESC covered the following scope:
- Sheet pile requirements and Specification
- Corrosion design
- Calculation of sheet pile modulus
- Connection detail of sheet pile and tieback system

Designs undertaken in all of these projects were in conformance with the relevant British Standards.

Figure 2 Initial platform works begins on site

Structural Requirements (Example for Phase IA)

The specifications for the Main Wall and the Anchor Wall are given in Table 1.

Table 1: Sheet Pile Requirements

Supplied piles by ESC are given in Table 2.

The sheet pile proposed for the Main Wall was a custom designed pile specifically suited to this project. The sheet pile was built in a modular style which allows the thickness of the plate to be varied to accommodate different stress levels and corrosion zones.
Table 3 shows the section modulus and moment capacity of each segment of the ESC46A (6059) sheet pile prior to corrosion loss.

Table 3: Segment Properties Prior to Corrosion Loss

The ESC18A sheet pile is a standard ESC product.

Full calculations of the derivation of section modulus for the ESC46A (6059) custom pile, and the ESC18A standard pile were supplied to the Client and their Engineers. All calculations were performed in accordance with the guidelines set out in BS 5950 Part 5.
Steel piles were manufactured and delivered in accordance with the requirements stated in the BS EN 10249 Parts 1 and 2. Steel specifications follow those stated in BS EN 10025:1993.
All piles contained welded elements. The welding procedure was designed and approved by accredited certification bodies (Lloyds) to ensure complete strength transfer across the welded joint.

Figure 3 ESC18B Anchor Wall Piles ready in the factory for shipment

Coating Requirements (Phase IA and others)

The specified coating for the sheet piles was for sand blasting followed by 50μm of primer and then 400μm of coal tar epoxy paint. The coating was applied to the entire front surface and two metres of the back surface of the Main Wall piles only.

ESC will be used a product called JotaCoat 550 for all painting works. ESC work closely with the paint manufacturer Jotun and have developed a painting specification that is designed to suit high corrosion environments.

Figure 4 Main Wall Sheet Piles at the Port ready to go

Figure 5 Pile Shoes made for the hard driving conditions

Corrosion Design (Phase IA and others)

The specification for the corrosion design is that the sheet pile must have a design moment capacity of 616 kNm/m after a thirty year period. Coating was not to be considered in this calculation.
Corrosion rates varied along the length of the pile depending on the corrosion zones. Likewise, moments along the length of the pile will vary with the maximum required moment occurring approximately halfway between the anchor point and the dredged level. The objective of the corrosion design was therefore to ensure that the moment capacity in this zone is at least 616kNm/m after thirty years.

Corrosion rates as stated in BS 6349 Maritime Structures Part 1: Code of practice for general criteria ( Table 25) have been adopted. The relevant rates have been summarised in Table 4.

Table 4: Corrosion Data

The loss of thickness in each segment will affect the section modulus of the pile and hence the bending moment capacity.

Figure 6 Anchor Wall Sheet Piles installed

These results are summarised in Table 5.

Table 5: Segment Properties Post Corrosion Loss

The stress of 230 N/mm2 is adopted from BS449 as the design stress for sheet pile walls using high tensile steel. It should also be noted that all the calculations made full allowance for panel buckling considerations in the thin plate sections.

Figure 7 Installation of the H Pile Cantilever Wall Section

Figure 8 Final installation of the Sheet Piles to depth is carried out by the IHC S90 Hydraulic DropHammer

ESC carried out the alternative design calculations on behalf of the Contractor (Athena SA) and submitted them for approval to the Client (RAK Government) and their Consultant (Gibb Ltd). All relevant drawings and engineering detailing was provided by ESC for all projects. Once approval was received the manufacturing was carried out in the ESC factory for delivery to the site.

Figure 9 Section Drawing for Construction of Phase IA

Figure 10 Excavation underway for the tie rod installation

As always, ESC personnel were on site to assist Athena SA during the beginning of the installation process. Several recommendations were made regarding piling guides and handling processes. ESC provided efficient Dawson Lifting Shackles that helped increase the productivity of the installation, while ensuring maximum safety during the process.

Figure 11 Tie rod installation is underway

Soil Profile

The existing seabed was between approximately -2.0 EL to +1.0 EL in the vicinity of the proposed wall. Subsequent filling activity has reclaimed the area to approximately +3.0 EL. Fill material is dense to very dense sandy gravel with cobbles and boulders.
The original seabed is a layer of medium dense to very dense silty sand, overlying a medium dense to very dense silty gravel layer with sandstone bands up to 8.0m thick.
Below the gravel layer are pockets of medium dense to dense sands, overlying a very dense sand layer with sandstone bands at approximately -13.0EL.

Figure 12 Finishing touches before the commissioning of the Port

Figure 13 Dredging to depth to allow the vessels to berth and its ready for commercial work

Sheet Pile Components List for ALL Projects

The tie rods for Phase IA-Extension were supplied by Dextra Manufacturing under the guidance and design of ESC. The rods supplied were M60mm of steel grade 700 in lengths of up to 24.6 metres. Tie rods were wrapped in Denso tape prior to installation.

Installation Details

Installation was done by pitching the sheet piles in a piling frame and driving to refusal with an ICE 815 vibro hammer. Piles were then driven to the final required level using an IHC S90 hydraulic hammer, together with a pile helmet.

Figure 14 Finished and ready to accept ships

Figure 15 The first ship comes alongside at Phase 1A August 2006