Liebherr and DBB Deliver Productivity Boost on Piling An innovative method of powering a vibro-hammer with the engine of a new 100 t-capacity HS8100 HD Liebherr duty cycle crawler crane is saving time and money for contractor Dutco Balfour Beatty (DBB). DBB and Liebherr Middle East FZE engineered the modification to the HS8100 HD being used for the piling job at Expo Village in Dubai, resulting in about 20% increased productivity for the piling operations. Tamer Shalash, DBB’s piling and ground engineering manager, stated that they are ahead of schedule and were set to complete the piling within four and a half months instead of anticipated six months. The time savings is “substantially due to a modification designed by ourselves and Liebherr, in which, rather than installing a separate power pack on the crane to drive the vibro hammer, we used the power of the crane engine. In this way, instead of using two engines to run the vibro hammer setup we had only one, and this was controlled by the crane operator,” said Ibrahim Hamdy, DBB’s plant and transport manager. The Liebherr duty cycle crawler cranes ranging in depth between 15 and 26 m (49 and 85 ft), and with diameters of 1,000, 900 and 750 mm (39, 35 and 30 in). The soil is sand for the first 4 m (13 ft) in depth, with mixed rock of varying hardness below that, and with a water table around 7 m (23 ft) below the surface. Oceanwide Center, a Landmark Project for Malcolm Drilling Dutco Balfour Beatty is using four Liebherr machines at Expo Village in Dubai “We therefore do not have the frame and power pack that is normally mounted on the crane, and so we save on weight and maneuverability. We do not need a separate operator for the power pack, so we save on manpower costs, and we save time because we eliminate the lost time required for communication between crane operator and vibro hammer operator,” Hamdy adds. According to Hamdy, using this setup, has saved costs on the purchase or rental of the power pack as well as on diesel and other operating costs. “We are working to a 24-hour cycle, and our highest rate of pile installation has been 43 piles during one cycle. Using this configuration, we are saving up to six minutes per pile. We are actually calculating that during one cycle we can save two or three hours.” Rotary drills are being used to bore the holes, with the Liebherr units driving the casing and then placing the steel rebar cage, in one length, into the hole. The contract requires 1,900 piles, 122 • DEEP FOUNDATIONS • MAR/APR 2017 Malcolm Drilling Company is putting its foundation expertise to work on the more than $1 billion Oceanwide Center complex located in the Transbay Area of San Francisco. Malcolm’s foundation work for this landmark project will require some of the most sophisticated deep foundation construction techniques ever employed in San Francisco. The foundation project includes a 70 ft (21.3 m) deep excavation, cutter-soil-mixing shoring walls, dewatering and drilled shafts greater than 300 ft (91.4 m) deep f o u n d e d i n Franciscan bedrock. The 2.4 million sq ft (222,967 sq m) development will have two mixed-use towers. The 625 ft (191 m) tall Mission Street Tower will hold a mix of hotel and residential space within its 54 stories. The 910 ft (277 m) tall First Street Tower will provide additional residential space and offices on 61 floors, and will be the West Coast’s tallest residential project and San Francisco’s second-tallest building next to Salesforce Tower. The project broke ground in December 2016, and is estimated to be completed in 2021.
