Data part, boundary conditions

bounda_dof 0 -lower_edge -vely
bounda_dof 1 -right_edge -velx
bounda_dof 2 -left_edge -velx
bounda_dof 3 -beam_point -velx
bounda_time 3 2.0 0. 5.0 0. 5.000001 -0.005 1.e8 -0.005
bounda_dof 4 -all -rotx -roty

In this calculation it is more convenient to prescribe velocities (instead of prescribing displacements), since in the experiment the velocity of point A has been prescribed. The bounda_dof 0, bounda_dof 1 and bounda_dof 2 specify conditions equal to the slope calculation of tutorial 1. The bounda_dof 3 needs more explanation. It specifies the velocity of point A of the sheet pile in time. Up to time 2.0, so during the first two excavations, point A is not prescribed. Then at time 2.0 it is fixed till time 5.0, so till the end of the loading at the top. Then after time 5.0 point A gets a prescribed velocity of $-0.005 \frac{m}{s}$, so to the left. The bounda_dof 4 suppresses two beam rotations which are not relevant in this 2D calculation; only the -rotz is relevant since it corresponds with in-plane 2D bending of the beam.

There is one subtle but important remark to be made. We impose the boundary condition for point A at the defined beam_point, so in fact at a geometry_point (see the previous definition of beam_point). This will only work correctly if at that point in space there really is a finite elements and their nodes. If on that point in space there is no node, no condition will be applied at all. This remark holds for all kind of data where you use geometries, e.g. loads on edges, post-processing on geometries, etc.; in the end, such data will only be applied on finite element nodes, so these nodes should be located on the correct locations.