One of the most challenging tasks in rock mechanics is the accurate evaluation of deformability and strength characteristics of jointed rock masses. Attempts to characterise large-scale rock mass properties in the laboratory are seldom undertaken due to the difficulty of obtaining and testing large samples. The in-situ interaction between intact rock blocks with discontinuities is very complex and it is generally not adequate to simply use un-modified laboratory-based measurements of rock properties within models which try to capture the global rock mass behaviour. The mechan-ical properties of intact rock and discontinuities can be determined in the laboratory by triaxial and direct shear methods. In this study the equivalent strength and deformability parameters of a real dam foundation, those of the Surqawshan Earth Dam in Iraq, were predicted using the Distinct Element Method (DEM). The results were compared with those obtained using the Rock Mass Rating and GSI systems.
One of the most challenging tasks in rock mechanics is the accurate evaluation of deformability and strength characteristics of jointed rock masses. A reliable estimation of the strength and deformation properties of a jointed rock mass is required in order to design dams constructed on jointed rock foundations safely and economically. The direct in-situ measurement of the mechanical properties of a rock mass is very expensive and time consuming (Zhang 2005, Zhang & Einstein 2004). At-tempts to characterise large-scale rock mass properties in the laboratory are seldom undertaken due to the high cost, the difficulty of dealing with large samples in the laboratory, and the time required (Hoek 1983). The mechanical properties of intact rock and discontinuities can be determined in the laboratory by triaxial and direct shear methods. However, the in-situ interaction between intact rock blocks with discontinuities is very complex and it is generally not adequate to simply use un-modified laboratory-based measurements of rock properties within models which try to capture the global rock mass behaviour. Numerical modelling provides a method that can help understand how laboratory-based measurements of rock properties relate to full-scale predictions of rock mass behaviour. The aim of this paper is to predict the equivalent strength and deformability parameters of a real dam foundation of the Surqawshan Earth Dam in Iraq using the Discrete Element Method (DEM) and two rock mass classification systems (RMR and GSI). The Universal Distinct Element Code (UDEC) from Itasca (Itasca 2011) was used in this work.
