... been subdivided into 500elements, and the figure shows the stresses in the pile after 100 , 200, . . . , 100 0 time steps. It appears that the block wave is traveling throughthe pile without any ... its shaft by shear stresses that are generated by an eventual movement of the pile, see Figure 2 .10. A. Verruijt, Soil Dynamics : 2. WAVES IN PILES 28 ........................................................................................................................................................................................................................................................................................................................................................................................................................ ... This is usually denoted as numerical diffusion.All this confirms the propriety of the choice (2. 110) for the relation between time step and spatial step. In a particular problem the spatialstep...