Geology and geotechnical evaluation of Doha rock formations

Abstract

A generalised ground model with geotechnical characterisation has been developed for the city of Doha, in Qatar, combining a wide range of ground investigation data and observations during the construction of projects that WS Atkins & Partners Overseas were involved with. The model proposes a geotechnical characterisation and ranges of parameters for the main units found at depths relevant to civil engineering activities. A geotechnical classification system is proposed to differentiate the Simsima Limestone subunits encountered on site, based on rock quality designation (RQD) values and weathering degree. The proposed classification system and the relevant geotechnical parameters have been validated during construction. The construction of all excavations, temporary retaining systems and tunnel excavations that rely on the information presented in this paper has been completed successfully. This confirmed a reasonable agreement between the theory presented in the paper and the practical conditions encountered on site. Best site investigation practices are discussed with highlights on difficulties encountered on site and how they were resolved. RQD and rock mass rating values were found to produce a good representation of the ground conditions while the applicability of the geological strength index classification is believed to be limited.

A review of piling industry practices in Dubai, UAE: proposed UCS-based correlations

“…The authors refer to the information presented by Karagkounis et al (2016) on the Doha rock conditions as the rocks encountered in Dubai present many of the same challenges in terms of site investigation and derivation of engineering parameters. This is of course with the exception of the karstic nature of the Doha Simsima Limestone.…”

“…Rock mass stiffness was estimated using available correlations from UCS results, following the recommendations by Karagkounis et al (2016) and subsequently back-analysed to match the load-deflection curves provided with the preliminary pile load test reports. This is further explained in the section headed 'Back-analysis'.…”

Calculation of Mohr-Coulomb Parameters for Rocks of Doha, Qatar

“…As already mentioned earlier, the method of converting directly from triaxial tests with low confinement loads gives exceedingly high friction angles, whereas the cohesion results are in reasonable agreement with Hoek & Brown (1997) method. Cohesion values from Fourniadis (2010) and Karagkounis et al (2016) are considerably lower. From all this, we can only preliminarily conclude that Hoek & Brown (1997) method likely gives the most realistic MC values.…”

“…In their work Latapie and Lochaden (2016) have criticized the Hoek & Brown (2002) conversion method to MC parameters, citing the fact that it only uses confinement stress range up to 0.25 UCS, as a shortcoming (in the same manner as Hoek & Brown 1997 procedure), in particular for slope and retaining wall problems. They also cited the fact that Intermediate Ground materials are governed by shear strength of the rock mass, rather than by discontinuities, as is often the case for hard, more intact rocks, and Karagkounis et al (2016) have implicated that this applies to Qatari rock masses. What concerns this issue, it was already shown by Vucemilovic et al (2021) that Qatari rock masses, for most part, are not Intermediate Ground material, and even softest RUS member characteristics conform to a very limited extent to its' criteria (average UCS was recorded at 12.9 MPa and transitional HB variables' changes from Carvalho 2007 are minor as seen in table 2).…”

Petrographic and petrophysical characterisation and structural function of the heritage stones in Fuwairit Archaeological Site (NE Qatar): implications for heritage conservation

“…The middle Eocene Damman Formation is the main source of traditional building stone in Qatar (Jassim al- Kholaifi, 2006;Karagkounis, 2016). However, younger limestones (Pleistocene-Holocene) of coastal origin, and less consolidated than the Dammam Formation, were also used as building stones in the vernacular buildings of Qatar .…”