Project Description

Athena SA and ESC proposed the ESC Combi-wall Tubular Pile system which eventually won the award from the Port of Fujairah and their Engineers MUC of the Netherlands. During the course of the design stage of the project ESC held site meetings in the UAE and visited MUC’s geotechnical and structural team in Terheijden, Netherlands. ESC ensured that all facets required by the Client and their Engineers were able to be met.
ESC not only worked with the owners but the contractor Athena SA had constant site visits and communication from ESC both during the design stage and the implementation stage of the project. Designs of the wall system took into account the preferred method of construction detailed by Athena SA and were adapted accordingly whilst at the same time ensuring the stringent safety factors of the Clients Engineers were followed in terms of the seismic and structural conditions.

The Port of Fujairah proposed to construct a new quay wall for an oil terminal facility to be constructed to the north of the existing port facility. The name of this project is Fujairah OT2. The main purpose of this quay will be as a vessel loading facility for oil products.
The type of retaining wall used is a steel tubular pile wall with sheet pile infills, restrained by tierods to buried sheet pile anchor wall. This wall was backfilled with locally dredged material.

Figure 1 Welding of the ESC Tubular Pile clutches at the factory in China

The design of the sheet pile wall was undertaken by ESC Al Sharafi Steel LLC and detailed in a series of reports. The scope of the design covered by these series of reports was as follows; i) Evaluation of geological data and existing site conditions to determine a range of geotechnical parameters for use in the designs.
ii) Analysis of the retaining wall and restraint system given the geotechnical parameters, site requirements and loading considerations, including seismic design.
iii) Specification and design of necessary sheet pile and tie rod components to withstand the calculated geotechnical and imposed loads
iv) Evaluation of the corrosion conditions, and design of the sheet pile system components to accommodate these conditions, including specification of protective coatings.
v) Various method statements required for specific tasks, including painting, bitumen sealing and clutch strength testing.

Figure 2 Completed ESC Tubular Piles waiting to be shipped to Fujairah Port

The design scope was broken into a series of design submissions which addressed each of the key design issues.
The scope of the design within these reports did not extend to the following issues;
i) Overall layout of the Port, including hydro dynamics, or other overall design considerations involved with developments of this nature.
ii) Environmental impact considerations, excepting specific products that may be specified in the design and have to comply with environmental requirements.
iii) Design of capping beams, fenders, quick release hooks, mooring rings, ladders or other fixtures on the sheet pile structure. The loads from these respective items will be considered in the design.
iv) Design of buildings, cranes, pontoons, dolphins or other structures associated with the project.
v) Cathodic protection and scour protection.

In addition to the design submissions, there was also a series of method statements and prequalification documents for specific activities. These method statements are listed in the table below;

Figure 3 Sheet piles stacked in the hold of the ship ready to go to the UAE

Figure 4 ESC Tubular Piles on deck waiting for unloading (the entire cargo hold was also filled with the Tubular Piles)

Figure 5 Unloading of the ESC Tubular Piles begins at the port of Fujairah, UAE

General Design Criteria

Project Criteria
The tender document provided for the design life requirement of the works (50 years), specific loading requirements, load case specifications, seismic requirements, structural dimensions and tidal information.
Data and requirements specified in this document will took precedence over standard specifications in Design Codes or other design publications used in this nature of work.

Standards and Codes
The British Standards were used as the basis for the design, unless specifically stated otherwise by the Engineer. These standards included, but were not limited to the following;

Other publications that were referred to are;
PIANC – “Seismic Design Guidelines for Port Structures”
Global Seismic Hazard Assessment Program – Global Seismic Hazard Map 1999

Computer Software
Computer based calculations were performed on PC computers, using software compatible with the Microsoft Windows® operating system. Reports were based in Microsoft Word and spreadsheet work done in Microsoft Excel. Reports were submitted in PDF format. Drawings were produced in AUTOCAD®.
The following specific design software was employed to assist with the Design;
i) PLAXIS 2D – V8 Professional
Plaxis is a finite element package intended for 2D analysis of deformation, stability and groundwater flow in geotechnical engineering. Using the Plaxis package, earth and retaining wall structures were constructed in a stage by stage approach, similar to the actual construction method. This allowed the modelling of stage loads and time dependant and cumulative effects. The package offered various soil models to simulate a variety of soil conditions, as well as time dependant control over ground water and pore pressures. Local and overall stability, deformations and loads on all structures were readily obtainable. The addition of the dynamics package allowed the modelling of the soil structures response to harmonic inputs, such as driving forces, wave actions and earth quakes.
ii) Static Probing
CPT data was analyzed using Static Probing by Geostru. The software provided graphical plots of the CPT readings, stratigraphic interpretations and tabulated soil parameters at each test location.
iii) STRAND 7
The STRAND software is a general purpose 3D finite element package, with both linear and non linear capabilities. Designed by Strand7 Pty Ltd in Australia, the software allowed the accurate modelling of intricate and detailed components, with complex load applications. The Strand software was primarily used for simulation of the steel structure elements and connections.

Discussion of Submissions
The following sections list each of the design submissions and discuss the design criteria, assumptions and philosophy that were addressed in each submission.

Evaluation of Geological Data
The purpose of this report was to evaluate the data from the soil investigations and laboratory tests and from this, determine accurate soil profiles across the project site, including the assignment of soil parameters.
Two soil investigation reports provided the data. One set dated back to 2006 and formed the basis for the Tender designs.
The second set of data was provided by a soil investigation that was carried out after the commencement of the works. This soil investigation consisted of 13 boreholes and 8 CPTs specifically targeted to the zones where the works are to be carried out. The results from these boreholes were the primary source of geological information, however the older set of logs were still maintained and used as a reference.
The results of the soil tests allowed the assignment of soil parameters to the various soil types and strata. These parameters were measured values, and were referred to as Representative Soil Parameters.

Figure 6 ESC Tubular Piles and ESC Sheet Piles are on site at Fujairah ready to undergo the blasting and painting

Seismic Evaluation and Considerations
Seismic design was in accordance with the PIANC document “Seismic Design Guidelines for Port Structures”.
Design acceleration was in accordance with UBC1997, volume 2, category 2. In addition, ESC provided an seismotectonic assessment of the regional hazard.

Retaining Wall Design Calculations
The local stability calculations of the retaining wall were performed in accordance with the requirements of BS8002. This included the following criteria;
i) Determination of Design Soil Parameters
Design soil parameters are defined as the representative parameters obtained in the evaluation of the geological data divided by a mobilization factor. This shall be applied as follows;
Where M is considered the mobilization factor and was taken as 1.2 for effective stress designs and 1.5 for total stress designs.
For seismic analysis, soil parameters c’ and tan f’ were factored by a variability factor of 1.2 and the undrained soil modulus, Eu, was used.
ii) Wall friction was taken as 2/3 of the representative f’
iii) Coefficients for active and passive earth pressures (ka and kp) were determined after Caquot and Kerisel, as given in BS8002 (not usually required for finite element work).
iv) Static surcharge of 50kPa was applied uniformly behind the wall. This was reduced by 50% in a seismic event. No live loads were considered in addition to this load.
v) An overdredge allowance of 500mm below the dredge level was allowed.
vi) Load cases were determined to consider the combined effect of geotechnical loads, surcharge loads, and seismic loads.
vii) Tidal lag was taken as the differential of MSL in the retained soil, and MLWS in front of the quay wall, in accordance with section 51.5 BS6349-1. Analysis was performed for a variety of load cases, considering stage by stage construction and the resulting cumulative effects.
The results obtained from the analysis of local stability using the above considerations were considered Design Values with no further addition of load factors or extension of the embedment. No moment reduction was applied to the walls due to relative soil / wall stiffness considerations (eg Rowe reductions).
Overall stability of the Main Wall, tieback and anchor wall structure was determined using representative soil parameters. A (c’f’) reduction analysis was then performed using the PLAXIS software to determine the overall geotechnical factor of safety.
For static load cases, the target factor of safety on overall stability was 1.4

Figure 7 Blasting begins at ESC's specially made onsite blasting machine

Figure 8 Painting works are underway on site

Main Wall Component Capacities
The design of the sheet pile system was performed in accordance with the requirements of BS5950-1.
In determining required structural capacity, the full yield strength of the material was utilized. Capacity of the Main Wall Components was then compared with the loads determined in
Retaining Wall Design Calculations Reports, and a structural factor of 1.2 for static conditions and 1.1 for seismic conditions maintained.

Anchor Wall Component Capacities
The design of the sheet pile system was performed in accordance with the requirements of BS5950-1.
In determining required structural capacity, the full yield strength of the material was utilized.
Capacity of the Main Wall Components will then be compared with the loads determined in Retaining Wall Design Calculations Reports, and a structural factor of 1.2 for static conditions and 1.1 for seismic conditions maintained.

Tie Rod Component Capacities
Tie rod design was performed in accordance with BS8081. Geotechnical loads were calculated from representative soil parameters and considered working load values. The effects of the various load cases were considered.
Tie rod capacity was designed to have a factor of safety of 2.0 (uncorroded) and 1.75 (corroded) on static load conditions, and a factor of 1.1 applied in seismic conditions. Separate additional tie rods provided for quick release hooks. No bollard loads were considered in the main tieback system.
Corrosion of the tie rod system was considered for 35 years.

Waling Beam Component Capacity
The design of the sheet pile system was performed in accordance with the requirements of BS5950-1. Corrosion was considered for a period of 35 years.
Capacity of the waling beam was designed to maintain a factor of safety of 1.2 in static conditions and 1.1 in seismic conditions.

Coating Requirements
The specified coating for the sheet piles is for shot blasting to SA2.5 followed by 2 layers of 250 micron Jotamastic 87. The coating was applied to the top 22.3m of the front of the ESC Tubular Piles and the back 4m. The ESC Sheet Piles had the full 22m length both sides with paint applied. The ESC Anchor Piles had no coating.

Figure 9 First the on land installation begins for the ESC Tubular Piles

Figure 10 Products Profile for the Projects Main Wall

Figure 11 The Jack Up Barge installs the ESC Combi-wall

Project : OT2, Fujairah Material Usage Summary

Figure 12 The hard ground conditions meant that the ESC-S10 Sheet Piles needed to be installed with the hydraulic drop hammer for the last four (4) metres once the hydraulic vibrohammer had done the initial installation

Figure 13 The ESC designed and supplied tie rods are installed into the main wall ready for the capping beam construction

Figure 14 The Quay Wall completion progresses

Figure 15 The Quay Wall Capping Beam is being constructed