Corrected Rock Fracture Parameters and Other Empirical Considerations for the Rock Mechanics of Rock Masses of Doha, Qatar

The objective of this paper is to provide insights into the intact rock and rock mass properties of the rock formations under the city of Doha, State of Qatar. We also intend to scientifically clarify these properties by presenting and statistically characterizing the ranges of the parameters, and by discussing the correlations between the parameters with respect to their usage and research potential. The rock quality designation corrected (RQD_C) parameter is validated and a new parameter, the fracture index corrected (FI_C), is proposed. The significantly improved correlation between RQD_C and FI_C is demonstrated and their derivation is explained. The paper demonstrates the correlation between the rock mass estimation parameters obtained through rock face mapping and discusses the applicability of the Hoek–Brown criterion to the studied rock masses, which is found to be relevant. A discussion about how properly performed triaxial tests can directly provide the rock constant m_i values for all geological members is presented. Other estimation approaches for m_i are also validated and compared with the existing knowledge base. Data for laboratory and field intact rock and rock mass parameters are combined using equations from various authors to obtain narrow ranges for rock mass strength and rock mass elasticity modulus values. Finally, within the framework of previous studies by other authors on the low-end transition range of rocks toward soils, it is shown that only the Rus formation member is sufficiently soft and can be included in the range.