GEOMECHANICAL PROPERTIES AND ROCK MASS QUALITY OF THE CARBONATE RUS FORMATION, DAMMAM DOME, SAUDI ARABIA

This study investigates the geomechanical properties, rock mass quality, and correlation relationships of the carbonate Rus Formation in the Dammam dome. The rock mass classification systems for tunneling purposes, the rock mass rating (RMR), and rock mass quality index (Q) were used to classify the rock quality from outcrop exposures. Rock mass quality is controlled by variable lithology, strength, weathering, multiple discontinuities, and solution caverns. The caverns are present and controlled by the fractures in the dome. Physical and geomechanical properties vary and the lower Rus shows lower average properties than the middle Rus. The RMR system classifies the rock masses into fair, good, and very good, while the Q system classifies the rock quality into poor, fair, and good. Both systems indicate that the lower Rus has lower rock mass quality than the middle Rus. The rock quality classification indicates that different support requirements might be needed for excavation, construction, and tunneling design in the lower and middle Rus. Characterization of rock quality on a regional scale within the dome can help to avoid potential hazards and possible problems in engineering structures or any expensive repair remedies.