Regional Report: DFI Middle East The Deep Foundation Institute was first introduced to the Middle East in 2008, and established as DFI Middle East in 2009. In the first Deep Foundation Conference in Dubai in 2008, DFI participated in several presentations and workshops. DFI Middle East has been co-organizer of the Deep Foundation Conferences in our region (Dubai, Abu Dhabi, Saudi, Qatar and Egypt). The last conference in Doha, Qatar in 2011 was a great success with over 200 attendees. In addition to conferences, we have arranged seminars in several countries to share our knowledge. One seminar, “Performance Design Based of Deep Foundation,” was held in Beirut with the Association of Engineers of Lebanon. Khaldoun Fahoum Ph.D., P.E., the incoming chairman of DFI Middle East was the moderator, along with me. Another seminar, held in Dubai jointly with the American University of Dubai, was conducted by Professor Rolf Katzenbach, whom we thank for supporting DFI Middle East. Both seminars were attended by over 100 people. Following are projects completed by construction companies actively supporting DFI, and the Arab Center for Engineering Studies. Large diameter sheet pile wall cofferdam by Orascom To meet Algeria’s energy demand for potential development, a 3x400 MW combined cycle power plant is being constructed by an Orascom Altsom consortium in Terga. The plant site is at level +45 m (+148 ft) on a steep hill along the Mediterranean Sea, and its intake pump house is on the shore line at elevation +1.50 m (+5 ft). Several challenges were encountered during the design and construction of the intake structure. One was that of designing the optimum shoring system to be constructed in such hard soil and on a site with almost 50% of the area offshore. The shoring system chosen was a 70 m (230 ft) diameter circular sheet pile with reinforced concrete ring beams at three levels to provide stability. Other challenges were the intake site platform and access roads, including a ramp built along the side of a hill. Almost 50% of the site was reclaimed in the open sea to allow the intake structure to be included excavating 50,000 m (65,400 cu yd) inside the cofferdam under the ground water level in the dry condition by means of 22 deep water wells distributed along the cofferdam circumference. The builders monitored the deformation of the ring beams during excavation to ensure stability. outside the cofferdam to reduce ground water seepage. The work 3 Offshore jet grouting project by Zetas Zemin in Qatar In spite of high budgets and construction difficulties, offshore structures are attractive solutions with expanding applications all over the world. Generally offshore structures are constructed in unfavourable soil conditions. An example is an offshore plaza structure in Doha Port, Qatar. Since marine sediments exist with a thickness varying between 3 m (10 ft) and 12 m (40 ft) on the Simsima Limestone bedrock, soil improvement was recommended prior to plaza construction. Also some locations on the site were Underwater jet grouting off the coast of Qatar An intake structure in Algeria includes the world’s largest cylindrical sheet pile structure built in the dry. The project required backfilling to +1.50 m (+5 ft) above sea level and providing protection against erosion and sea waves. The major challenge was driving the sheet piles in hard soil and constructing jet grouted columns AUTHOR: Mamdouh Nasr, Ph.D., P.Eng. Chairman of DFI Middle East; Regional Director, Middle East, Implenia Construction Ltd. filled, and dredging of the made ground was required before soil improvement works. The seabed was dredged at the depth of -6.00 m (-19.7 ft), and a flat platform was formed prior to soil improvement works. For soil improvement, an offshore jet grouting technique was designed in accordance with the soil conditions and structural surface loadings; 80 cm (31.5 in) diameter jet grout columns were constructed to bedrock. The system was modeled in Plaxis 3D Foundation and checked to fulfill the settlement criteria. Jet grouting was performed from a barge and a cantilever platform simultaneously to meet the tight construction schedule. After the soil improvement works, the seabed was dredged and plaza blocks placed on a granular capping layer on the jet grout columns. For quality control, uniaxial pressure tests were performed on core samples from the jet grout columns. For Doha Port, selecting a proper soil improvement method was important, and jet grouting proved again to be a convenient method because of versatile equipment, high production rate and a reliable output with a sufficient quality control for offshore soil improvement works. DEEP FOUNDATIONS • MAR/APR 2012 • 21
