## 5 Numerical Simulation of Plate Load Test Mechanisms  
In this study the plate load tests conducted at the Bazoft dam were simulated numerically aiming at illustrating the key parameters and mechanisms involved in the test. The sophisticated 3D finite difference code Flac-3D developed by Itasca Inc. [20] was used to simulate the test condition at actual scale. This code is equipped with sophisticated mesh generation, material behavior modeling, etc. capabilities and is capable of considering complex boundary conditions. The Bazoft dam right abutment geometry, test gallery geometry and location, test gallery-induced stress regime, PL test geometry and condition (loading and unloading cycles) were considered in the simulations and the effects of loading plate diameter and depth of displacement measurements locations on the calculated moduli were investigated.  
Based on conducted geological and geotechnical assessments, the rock mass of the right abutment consists of massive limestone. Standard rock mechanics tests (uniaxial compressive test, Brazilian test, triaxial test) were conducted on representative rock samples obtained from geotechnical boreholes. Moreover, a comprehensive survey and mapping of dam abutments was carried out to determine the in-situ rock mass conditions. Combina  
Figure 5: Rock displacement changes beneath the plates as a function of depth for all loading cycles [19].  
tion of obtained laboratory data and in-situ mappings enabled the determination of rock mass ins-situ parameters (Table 1). Two exploration galleries were excavated in the right abutment and in-situ plate load tests were carried out in these galleries. The estimated Poisson's ratio and RMR for the rock mass were 0.3 and 68-78, respectively [19]. A 3D model of the right abutment of the Bazoft dam and its test gallery was constructed. Figure 3 illustrates the actual view of the right abutment and the modelling domain considered for 3D modelling. In Figure 6 the actual PLT set up and the constructed 3D model of the right abutment and test gallery are illustrated. Figure 7 shows a magnified view of the constructed numerical model of the jacking test location and the displacement measurement borehole. In line with the pattern and location of displacement measuring points in actual test, measuring points were considered within the model and (Figure 7).  
In the conducted numerical analysis, the Mohr-Coulomb constitutive model was used to simulate the rock mass behavior. Because of the plastic deformations associated with loading/unloading cycles, which affect the slope of the stress-strain curve (deformation modulus), this simple model was selected for the PLT simulations. The model geometry, material properties, and boundary conditions used in the analysis were selected based on Bazoft dam site conditions. To determine the load-displacement curve, five loading-unloading cycles were simulated. The simulated loading cycles were applied as was  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Properties**} & **Density** & **UCS** & **Elastic/Deformation** & **Cohesion** & **Friction Angle** \\  & **(gr/cm3)** & **(MPa)** & **Modulus (GPa)** & **(MPa)** & **(Degree)** \\ \hline Intact Rock & 2.6 & 48.2 & 14.2 & 2.8 & 41 \\ Rock Mass & 2.6 & 7.3 & 9.6 & 2.1 & 42 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Physical and mechanical properties of the Bazoft dam right abutment rock [19].  
Figure 6: (**a**) View of the Bazoft dam right abutment Flac-3D model, (**b**) View of the simulated test gallery and the horizontal PLT set up, (**c**) View of the vertical PLT set up.  
instructed for the in-situ tests and based on standard guidelines. At the last cycle, the rock mass loaded up to 25 MPa. In the base run model, the simulated circular loading area had a diameter of 80 cm which is equal to the diameter of loading plates used in the actual in-situ tests.