Foundation design for the Emirates Twin Towers Dubai






Ground investigation and site

characterization

Preliminary geotechnical data for the site were available

from earlier investigations via a series of boreholes drilled to

about 15 m depth. These revealed layers of sand or silty

sand overlying very weak to weak sandstone. For the twin

tower development, it was clear that this preliminary infor

mation

was inadequate; hence, a comprehensive investiga

tion

was carried out. This investigation involved the drilling

of 23 boreholes to a maximum depth of about 80 m. The

deepest boreholes were located below the tower footprints;

boreholes below the low-rise areas tended to be considerably

shallower. Standard penetration tests (SPTs) were carried out

at nominal 1 m depths in the upper6mofeach borehole and

then at 1.5 m intervals, until an SPT value of 60 was

achieved. The SPT values generally ranged between 5 and

20 in the upper 4 m, increasing to 60 at depths of 8–10 m.

Rotary coring was carried out thereafter. Core recoveries

were typically 60%–100%, and rock quality designation val ues

were also between about 60% and 100%.

Figure 2 shows the borehole information along a section

that passes through the two towers. It was found that the

stratigraphy was relatively uniform across the whole site, so

it was considered adequate to characterize the site with a

single geotechnical model. The ground surface was typically

at a level of +1 to +3 m Dubai Municipality datum (DMD),

and the groundwater level was relatively close to the surface,

typically between 0 and –0.6 m DMD. The investigation revealed

seven main strata, which are summarized in Table 1

by material descriptions commonly adopted in Dubai.



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