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56 400 350 300 Lateral Force (kips) 250 200 150 Test1, Cap1 100 Test1, Cap2 50 Model 0 0.0 0.5 1.0 1.5 2.0 Displacement (in) Figure 5-3. Simulated and tested displacement-load results for pile group in virgin clay. It can be seen that the soil parameters calibrated from the Figure 5-2. Finite element mesh for single pile test in virgin clay appear to be appropriate to the pile model of pile group in virgin soil. group test. The FEM model of pile group in virgin clay can sim- ulate the essential load-displacement response of the test. The pile heads are extended into the cap base for 0.5 ft to 5.3 Pile Group Model in Virgin account for the cap pinning effects on the pile head rotation. Clay with Excavation The pile group in virgin clay with excavation provides the 5.2 FEM Model for Pile Group estimation of the passive force by the unsaturated clay against Model in Virgin Clay the pile group. A similar mesh design strategy was followed The pile group in virgin clay provides the basic data for com- for the FE model of pile group in virgin clay without excava- parison with the pile group with soil improvements. The mesh tion. Once again, a displacement control method was used used for the FEM pile group model in virgin soil is shown in for this problem. The node on the pile top was selected for Figure 5-2. A total of 50,247 nodes and 44,796 elements were the displacement control, which is laterally displaced to 1.5 in. in the FEM mesh. A displacement control method is used The maximum displacement was produced using 50 loading in analyzing the pile group test. The node on the pile top is selected for the displacement control, which is laterally pushed 400 up to a maximum displacement of 1.5 in. The static displace- ment is applied in 50 steps with a pile head lateral displacement 350 of 0.03 in. per loading step. 300 Lateral Force (kips-ft) The load-displacement response curves computed by the FEM are plotted in Figure 5-3 in comparison with the measured 250 curve. Generally, they exhibit good agreement with test data 200 from both Cap 1 and 2 of Test 1. The load-rotation response 150 curve computed by the FEM is plotted in Figure 5-4 and the Test1 Cap1 results seem to plot between the test data Cap 1 and 2 of Test 1 100 Test1 Cap2 at the beginning loading stage and thereafter tend to be close to 50 test data of Cap 2 and has considerable discrepancy to the test Model data of Cap 1. However, the load rotation test data of Cap 1 was 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 somewhat smaller than that of Cap 1; it was unclear whether Rotation (degree) this resulted from measurement errors or from the fact that the corbel on Cap 1 did not extend across the entire cap as did the Figure 5-4. Simulated and tested load-rotation corbel for Cap 2. response curve results for pile group in virgin clay.