6.4.1 Excavation sequence
Simulating excavations in numerical models poses no conceptual difficulties. However, the amount of effort required to construct a model depends on the number of excavation stages to be simulated. The most accurate solution is obtained using the largest number of excavation steps, because the real load path for any zone in the slope is closely followed (Figure 17). A reasonable approach regarding the number of excavation stages has evolved over the years. Using this approach, only one, two or three excavation stages are modeled. For each stage, two calculation steps are taken. In the first step, the model is run elastically to remove any inertial effect caused by sudden removal of a large amount of material. Second, the model is run allowing plastic behavior to develop. Following this approach, reasonable solutions to a large number of slope stability problems have been obtained.
Figure 17: Show the sequential excavation