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SIRTE COMMERCIAL HARBOUR – DETAILED DESIGN FOR QUAY AND SLOPE PROTECTION

MR. JANUZ WISZNIEWSKY – CEO OF PORTY SA – (jacek.sledz@hydrobudowa.com.pl)

A/TO :
PORTY SA
GRUNWALDZKA 135
80-264 GDANSK
POLAND

Mr. Marek Fyalkowski – POLIMEX – MOSTOSTAL : marek.fyalkowski@interia.pl

COPY BY Eng. Alkailani Omer – LMTA Project Manager - Sirte – Libya: alkilani7566@gmail.com
EMAIL:

MARC DE LA TORRE – PROJECT MANAGER

DE/FROM : REF/SOG/CHRONO. MDT/ELE/2 71 2167 -
marc.delatorre@sogreah.fr

N°TEL : +33 (0)4.76.33.41.86 DATE : 16/5/2008

OBJET/
SUBJECT:
COMMENTS ON QUAY WALL DESIGN REVIEW CARRIED OUT BY ROYAL HASKONING

REF/
PROJECT
2712167 – SIRTE COMMERCIAL HARBOUR

Dear Sir,

Please find hereafter our comments on the design review document carried out by Royal Haskoning ref
9S31186 dated 7/4/2008, on our detailed design and technical specifications documents ref 2712167 R2
dated September 2004.

Article from RH report Sogreah comments

2.2 General remark • We confirm that our design is only a detailed design and that the contractor
shall provide execution studies in order to issue detailed construction
drawings and reinforcement drawings.
• Design criteria to be applied for the works are given in the Volume 1: report –
Chapter 6 and in the Volume 4 – Section 100 – Chapter 4.
• As indicated in the technical specification chapter 4.1, “the Contractor shall
be deemed to have interpreted these criteria to his need and /or made other
verification necessary to satisfy himself before submitting the tender, as to all
relevant matters”.
• Please note that as specified in the VOLUME 4 – section 100 – Chapter 9.1,
it is specified that “the Contractor shall design (to the extend specified in the
Contract), execute and complete the works in accordance to the contract and
with the Engineer instruction, and shall remedy any defect in the works”. In
consequence it was supposed that the contract to be awarded with the
Contractor was something like a “design and built contract”.
3.1 Codes standards Please note that as indicated in the VOLUME 1 – Section 6.1.3, French
standards have been used for our design. Nevertheless, in the VOLUME 4 –
section 5, we have indicated that other standards can be used by the Contractor
(such as BS 6349 for example).
In the chapter 5.2.1, it is also indicated that “After the Engineer’s approval has
been obtained, the Contractor may apply standard and regulation other that
those specified …”
3.2.1 – Dead weigth of • The result obtained by the Contractor Porty during the construction of the

SOGREAH CONSULTANTS SAS – B.P. 172 – 38042 GRENOBLE CEDEX 9 – FRANCE – WWW.SOGREAH.FR
Siège Social : 6, rue de Lorraine – 38130 Echirolles – France – Tél. 33 (0)4 76 33 40 00 – Fax 33 (0)4 76 33 42 96
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N° Identification TVA : FR 40 444 523 526
 16/5/2008 – PAGE 2/1

the structures and breakwater show that a density of the concrete blocks equal to 24 KN/m3
buoyancy loads is possible.
• The specified concrete density shall be taken as 24 KN/m3.
3.2.2 Soil loads We confirm that we have assumed phi=35° and y’ =11KN/m² an yh =19 KN/m,
which is a conservative approach for a compacted backfill and a selected quarry
run behind the quay wall.
3.2.2 Differential water The difference between the MHWS and the MLWS is 30cm in 6 hours.
load Consequently we consider that a water level difference of 0.2m is more than
realistic.
Sea level rise has not been taken into consideration. Considering the accuracy of
the existing data on the water levels, the loading combinations applied and the
safety factors obtained for the stability of the quay and the unknown expecting
sea level rise to be taken into consideration, we consider this comment not
justified.
3.2.4 Mooring load Reinforcement in the capping beam shall be determined by the contractor.
3.2.5 Seismic load As shown in the appendix 1 of the VOLUME 2, the horizontal acceleration has
been taken equal to 0.1g based on French regulation (AFPS zone 2).
The horizontal acceleration of 0,06 or 0,05g is based on the design criteria given
in the Libyan standards. With an amplification factor of 1,8, we are close to 0,1g.
Therefore we confirm our assumption with 0.1g.

3.3.1 Load The applied load combinations refer to the French standard ROSA 2000 used to
combinations design maritime structures. The approach developed in this standard is an
application of the approach developed in the EUROCODE with partial load
factors.

3.3.2 Friction factors Our approach is conservative

3.3.3 Design criteria We confirm our approach based on the French standards ROSA 2000 which is
based on the approach developed in the EUROCODE.
Please note that in comparison with BS6349, partial load factors are added and
loading combinations are define based on SLS and ULS states with frequent,
rare, fundamental and accidental definition.

3.4.1SI information and We remind that the Contractor will be responsible of the final design as indicated
soil profile in the technical specifications. Therefore the contractor shall verify if the existing
investigations are sufficient to perform its execution design.
As shown in the drawing n°06 in VOLUME 3, the quay wall is directly placed on
the calcarenite layer. Only one borehole (B7) show layer of 2m of Silty fine sand.
Considering the safety factors obtained (>2), we think that our assumption are
safe.
We suggest that the Contractor during its execution design will model a typical
section of the block work quay wall using a non-linear finite element software for
geotechnical engineering (such as Plaxis 8.2) to check the factor of safety by the
“phi-c reduction” method i.e. by successively reducing the soil parameters until
the soil system fails and then calculates the factor of safety calculated as unity
plus the reduction factor at failure.
After these computations, adaptation of the design could be provided but we
think that our design will be confirmed.
3.4.2 design criteria Safety factor for geotechnical stability:
- Normal condition: 1.5
- Seismic condition: 1
3.4.3 Slip circle See response in 3.4.1
analysis
3.4.4 Settlement No calculations have been performed for settlement.
analysis

MDT/ELE/2 71 2167 -
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4.1.1 Fixation point The design has been based on the existing jetty which is under operation without
piles any problem.
Detailed calculation note were provided at that time (ref. Sogreah report 712027
R1 dated November 2000).
Justification of the piles is given in this report. In the report dated of 2004, we
have updated the design of the deck using STAAD 3.

4.1.2 Maximum load on Uniform load of 3T/m² is the unfavourable condition and cannot be concomitant
piles with a straddle or a crane load. Please note that we have considered a safety
factor of 2 for the vertical load on pile.
Please also note that the lengths mentioned in our design have been proposed
based on the existing jetty where static load tests have been performed.
These load tests shall also be repeated by the contractor at least for 5 piles (see
Section 1000 – Volume 4).
4.1.3 Landside earth See the 2 points above
volume
4.2 Slope stability Slope stability has been checked in our previous design for the existing jetty. The
Contractor will have to verify this aspect within its execution design.
4.3.1 Concreted steel The sacrificial anodes shall be changed after 15 years and shall be foreseen
piles within the maintenance program of the port.
Please note that we have also taken into account a sacrificial thickness for
corrosion purpose of 7,5mm.
Please also note that an epoxy coating of 450 microns is specified (see VOLUME
4 – Section 1000).
4.4.2 Temperature The temperature mentioned is the yearly variation.
stresses Due to the length of the structure (43m), the temperature variation will have a
negligible effect which should be taken into consideration for the execution
design..
5. Fenders The cylindrical fenders were required by the client and have been changed in the
latest revision. In reducing the berthing speed at 0.15m/s (which is common), the
cylindrical fenders are sufficient and are more adapted to local conditions .
7. Design drawings Reinforcement drawings are part of the execution drawing to be carried out by
the Contractor.
We agree that reinforcement is required for the capping beam.
The technique proposed is used since a lot of years in the Mediterranean sea. A
staggered grid could also be used by the Contractor in adapting the design.
A width of the scour protection of 8m is more than sufficient base don our
experience.
The anchorage of the bollards shall be checked between the supplier and the
Contractor. We agree that sometime the anchors are made straight with bolts
and plate at the end based on the recommendations of the supplier.
8.Technical Section 100: It is confirmed that the design is the responsibility of the Contractor
specifications as indicated in chapter 9.1.
Section 300 We agree concerning the tolerance for the 300kg rock. The tolerance shall not be
more than 30cm for all depth.
Tolerance for the levelling stone shall not exceed +/- 5 cm.
Section 900 We agree to say that a preconstruction survey shall be performed by the
Contractor as basis for measurement as specified in Section 100.
Section 1000 The bearing capacity shall be determined by the Contractor with a minimum of
3700KN as specified in chapter 3.16.4
Section 1200 See response above

Best regards

Marc DE LA TORRE
Sogreah Maritime

MDT/ELE/2 71 2167 -