Geotechnical Logging of Exposed Rock Masses of Khans Area in Dohuk Governorate, Northern Iraq.

Abstract

The current study depends on geotechnical logging, represented by field and laboratory logging to evaluate the rock masses which consist from limestone rocks belonged for Pilaspi Formation at the Khans Dam site in northern Iraq. Field logging depened on discontinuities and intact rock in the rock masses, using the rock mass rating according to Bieniawski (1989). The values ranged between (49-59) ,these  rock masses are considered Fair. As for the Rock quality designation based on the discontinuities and the distances between these discontinuities, their values ranged between (71.17-92.681%), meaning between (moderate to very strong). As for the geological strength index of the rocks, its values ranged between (54-64) which  rock masses are located between (Fair to good).  according to the plan adopted by (Sonmez & Ulusay, 2002 and Modified Hamasur, 2009). As for the laboratory test, it represented the results of the unconfined uniaxial compressive strength of these rocks on two banks, as it is located between (7.87MPa-20.64 MPa). As for the results of tensile strength using the indirect method (Brazilian method) and according to the classification (Deere & Miller, 1968), their values ranged between (2.10MPa - 2.62 MPa), it is considered medium. As for the petrophysical properties, they were represented by the dry density in gm/cm3, and their results ranged between (2.01-2.37)gm/cm3, while the water content values ranged between (0.178%-0.961%). As for the true specific gravity of these rocks in all stations, their values ranged between (2.55-2.62), while the total porosity values ranged between (6.30% -21.99%), and the absorption ratio results, their values ranged between (2.56%-10.91%). As for  the test of the Petrographic properties of the thin section rock under microscope, it was found that they consist of limestone and dolomitic with diagenetic process and dissolution and cementation.