## 4 Plate Load Testing at the Bazoft Dam Site  
The Bazoft Dam and Hydroelectric Power plant project include the design and construction of a 211 m high, double curvature, concrete dam, and an underground powerhouse, located 200 km SW of ShareKord, Chaharmahal and Bakhtiary Province in southwestern Iran. The bedrock consists of two geological units from the Eocene, Oligocene, and Miocene. The Asmari formation (As's in Figure 2b) forms the left abutment consisting of marly-limestone and thin layers of limestone. The right abutment and the lower part of the left abutment are built over the Jahrom formation (Ja in Figures 2b and 3) which consists of crystalline massive limestone with interlayers of marly limestone. Figure 2 shows the plan and longitudinal views of the Bazoft dam site illustrating the site topography, abutment geometry, and site general geology. In Figure 3 a magnified view of the right abutment, the location of the test gallery, overall view of the Jahrom (Ja) formation, and modeling domain considered in the 3D analyses are shown.  
Three plate load tests were carried out in the right abutment of the Bazoft dam. Two PLTs were set-up in a horizontal direction and one in a vertical direction. The plate load test conducted in the lower gallery (PLH3-RG1) was set up in the horizontal direction and located at about mid-length of the test gallery as illustrated in Figure 3. The test was carried out with five loading and unloading cycles. Figure 4 shows a summary of the test results obtained. Figure 4a illustrates the stress levels that are applied to rock mass in five consecutive cycles. These stress levels are typical of plate load testing practices and are typically selected by the dam design team based on the probable stress levels that are going to be applied to the abutment by the dam once it is constructed and in operation. Once the load is increased to the predefined level in each cycle, it will be kept constant to allow the rock mass to reach an equilibrium state with the applied load and no further deformation has occurred in the rock mass. The flat portion on all graphs is indicative of this stage. After the last cycle, the rock is reloaded to the last cycle stress level and the creep behavior of the rock mass is assessed. Further details on the testing procedure can be found in [5; 6; 7; 10]. Figure 4b,c illustrate the change in rock mass deformation at varying depths beneath the loading plate for the right and left plates respectively. As can be seen from the results, the displacement magnitude at sensor \(A\) location which is closer to the surface is significantly higher than the other sensors which are installed further deep into the rock mass. Looking at these figures indicates the significance of displacement measuring depth on the determined final deformation modulus. This issue is investigated numerically in the next sections. In Figure 5 the peak displacement at the end of each loading cycle is plotted for all sensors comparatively for the right and left test gallery walls. Referring to this figure, the displacement variations for the right and left plate are different which means that the rock mass deformational behavior on test gallery sides are different. Furthermore, the significance of deformation at the shallow anchoring points is noticeable compared to deeper measuring points. This indicates that the displacement data recorded at higher depths are not realistic in terms of rock mass behavior given the applied load level.  
Figure 2: Overall views of Bazoft dam site; (**a**) Plan view of site topography and (**b**) Longitudinal view of abutments geometry and general geology.  
Figure 3: Magnified views of the right abutment, conducted PLT location, and modelling domain boundary.  
Figure 4: A horizontal plate load test results at the Bazoft dam right abutment: (**a**) Pressure-time history, (**b**) Displacement-time variations (right plate), (**c**) Displacement-time variations (left plate) [19].