Proceedings of ICE Civil Engineering 162 November 2009 Pages 25–33 Paper 09-00036 doi: 10.1680/cien.2009.162.6.25 Keywords geotechnical engineering; foundations; piles & piling Foundation design for the Pentominium tower in Dubai, UAE Kamiran Ibrahim MSc, PhD The Pentominium tower in Dubai, UAE will be the tallest residential is regional technical director at Hyder Consulting, Middle East, building in the world at over 100 storeys tall when completed Dubai, UAE in 2012. This paper describes the design of the tower’s piled raft foundation in the local carbonate soils and rock. Geotechnical investigations are outlined, along with how the effect of the proposed tower on neighbouring structures, single-pile response and impact of cyclic degradation were assessed. A description Grahame Bunce of the numerical analyses used to evaluate the overall piled raft MSc, CEng, MICE response under various static and wind loading combinations is is technical director at Hyder Consulting (UK) Ltd, Guildford, UK presented as well as some of the techniques used to optimise the foundation design, including preliminary pile testing. The Pentominium residential development is the Jumeira Palm in the United Arab Emirates located approximately 500 m to the east of (UAE) (Figure 1). The development comprises Dubai Marina and south of the beach near the construction of a tower over 100 storeys tall Catherine Murrells 0 m 200 MA, MEng, CEng, MICE is principal geotechnical engineer Beach at Hyder Consulting (UK) Ltd, Guildford, UK American College Dubai international Marine Club Marina 23 tower Metropolitan Club Pentominium tower Forte Grand Hotel Dubai Marina Sheik Zayed Road Figure 1. Location of the Pentominium tower on the Dubai waterfront Delivered by ICEVirtualLibrary.com to: CIVIL ENGINEERING IP: 194.143.169.130 25 On: Wed, 22 Sep 2010 14:28:31 IBRAHIM, BUNCE AND MURRELLS and associated podium structure (Figure 2). It Geology Geotechnical investigation and testing is set to be the tallest residential building in the world when completed in 2012. The geology of the UAE and the Persian The ground investigation was undertaken All site levels are related to Dubai Municipal- Gulf area has been substantially influenced by ACES and consisted of sinking eight cable ity datum (DMD) and original ground level is at by the deposition of marine sediments associ- percussion boreholes with rotary follow-on about 5 m DMD. There are six basement levels ated with numerous sea level changes during methods, in-situ testing and laboratory testing and the structure is supported by a piled raft relatively recent geological times. With the (including specialist testing) on selected sam- system comprising large-diameter bored piles exception of mountainous regions shared ples. The boreholes were drilled to 80–125 m cast in situ. The pile cut-off levels are founded with Oman in the north-east, the country is deep with standpipe piezometers installed to about 24 m below existing ground level at an relatively low-lying, with near-surface geol- monitor the groundwater table. The scope of elevation of −19.4 m DMD. ogy dominated by deposits of Quaternary to in-situ testing is summarised as follows The area of the site is very limited with the late Pleistocene age, including mobile Aeolian structure extending to all boundaries. In addi- dune sands, sabka/evaporite deposits and n standard penetration testing tion, construction on the adjacent Marina 23 marine sands. n packer permeability testing tower is underway, with a number of levels of Dubai is situated towards the eastern extrem- n pressuremeter testing at 3 m intervals in superstructure completed before piling started ity of the geologically stable Arabian tectonic three of the boreholes on the Pentominium tower in 2008. plate and is separated from the unstable Iranian n geophysics (cross-hole, cross-hole tomog- The client for the project is Trident Inter- fold belt to the north by the Persian Gulf. It raphy and down-hole testing). national Holdings and the architect is Aedas. is therefore considered that the site is located Hyder Consulting carried out the detailed design within a moderately seismically active area. Disturbed, undisturbed and split-spoon of the foundation, substructure and superstruc- However, it was indicated from the structural samples were obtained from the boreholes for ture. Arab Centre for Engineer Studies (ACES) analysis that the wind effect was more critical laboratory testing purposes. The undisturbed carried out the ground investigation and Swiss- than the seismic effect as is typical for structures samples were obtained using double-tube- boring Limited was the piling contractor. of this size in Dubai. core barrels from which 92 mm nominal core +10 metres DMD Very loose to loose sand BH02 +5 BH06 BH03 0 Medium dense to very dense sand –5 Very dense silty sand with sand stone fragments –10 Sandstone –15 Gypsiferous sandstone –20 Calcisiltite/conglomerate/conglomeritic calcisiltite –25 –30 –35 –40 –45 –50 –55 –60 –65 Sandstone –70 Calcisiltite –75 –80 –85 –90 –95 Interbedded siltstone and gypsum –100 –105 Assumed geological unit based –110 on existing boreholes –115 Base of borehole data –120 Groundwater strike Figure 2. Artist’s impression of the Pentominium tower, which, at over 100 storeys tall, will be the highest residential building in the world when completed in 2012 Figure 3. Geological long-section through three of the boreholes Delivered by ICEVirtualLibrary.com to: 26 PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS – CIVIL ENGINEERINGIP: 194.143.169.130, 2009, 162, No. CE6 ISSN 0965 089 X On: Wed, 22 Sep 2010 14:28:31 FOundatiON DESIGN FOR THE PENTOMINIUM TOWER IN Dubai, UAE diameters were recovered. The laboratory Pressuremeter initial Resonant column 0.001% Percentage values testing included the following standard and Pressuremeter reload 1Cyclic triaxial 0.1% relate to the level Pressuremeter reload 2 Cross-hole geophysics of strain at which specialist tests Stress path 0.01% Strata the samples are Stress path 0.1% Design line at small strain tested n standard classification testing 0 n chemical testing –5 n unconfined compression tests m DMD –10 : : n cyclic undrained triaxial –15 n cyclic simple shear vation –20 n stress path triaxial testing n resonant column Ele –25 n constant normal stiffness testing. –30 –35 The standard ground investigation testing –40 was carried out following British standards BS –45 59301 and BS 1377.2 Four preliminary trial pile tests were also –50 carried out to determine single-pile load– –55 settlement behaviour and to assess the pile –60 capacity in skin friction. –65 –70 Geotechnical conditions and parameters –75 The ground conditions comprise a horizon- –80 tally stratified sub-surface profile. Three layers –85 of sand, varying from very loose to medium –90 dense to dense as elevation decreases, overlie –95 layers of very weak to weak sandstone, gyp- –100 siferous sandstone, calcisiltite, conglomerates –105 and calcareous siltstones. An idealised ground profile used for the –110 whole site is presented in Table 1 and a sec- –115 tion through three of the boreholes is shown –120 in Figure 3. –125 The geotechnical stiffness parameters for 0 1000 2000 3000 4000 5000 the design of the foundation were determined Elasticity modulus: MPa from the tests carried out on the strata at dif- Figure 4. Young’s modulus E' values derived from geotechnical testing ferent strain levels. It is presented in Mayne and Schneider3 that rock behaviour for defor- mation analyses, which would include piled Table 1. Idealised ground profile and geotechnical parameters rafts, ranges between strain values of approxi- Sub- Level at Unconfined Undrained Drained mately 0.01–0.1%, which correlate with Strata strata Material top of Thickness: compressive modulus* modulus* number number stratum: m strength: E : MPa E': MPa testing results from the pressuremeter, stress m DMD MPa u path triaxial, resonant column, cyclic triaxial Very loose to loose +1.40 to 1a slightly silty sand with . 2.70 – – 2 testing and geophysics which are presented on occasional sandy silt +5 59 Figure 4. 1 Medium dense to very −0.13 to It should be noted that the design line 1b dense slightly silty to . 9.50 – – 36 silty sand +5 59 shown on Figure 4 is for small strain design Very dense silty sand with . at 0.1% strain. The stiffness values provided 1c sandstone fragments −7 50 3 00 – – 75 in Table 1 are for the larger strain levels of Very weak to weak calcarenite/calcareous . approximately 1% determined from standard 2 2 sandstone interbedded −10 50 2 20 0 8 125 100 correlations with unconfined compressive with cemented sand strength results as presented in Tomlinson Very weak to weak . 3 3 gypsiferous sandstone −12 70 5 30 0 8 125 100 and Woodward:4 drained Young’s modulus at 4a Very weak to moderately −18.00 2.50 0.8 125 100 large strain E' = M j q , where M is the ratio . r u r 4 4b strong calcisiltite/ −20 50 950 3 0 350 280 of elastic modulus of intact rock to its uniaxial conglomerate/ . 4c conglomeritic calcisiltite −30 00 34 00 2 4 250 200 compressive strength, j is the mass factor and 5 5 Weak sandstone −64.00 2.60 2.4 250 200 q is the uniaxial compressive strength. u 6 6 Very weak to moderately −66.60 17.40 4.1 250 200 Non-linear stress–strain curves were devel- strong calcisiltite . oped for the rock strata based on all the Very weak to moderately >38 00 weak claystone/siltstone . (proven . ground investigation data. The curves were 7 7 interbedded with gypsum −84 00 to base of 3 0 250 200 fitted to the data using hyperbolic functions as layers boreholes) 3 presented by Mayne and Schneider and are * Note that Eu and E' values relate to large strain level (about 1%) of the strata Delivered by ICEVirtualLibrary.com to: ISSN 0965 089 X PROCEEIP:DINGS 194.143.169.130 OF THE INSTITUTION OF CIVIL ENGINEERS – CIVIL ENGINEERING, 2009, 162, No.