When introducing the reinforcement into the soil body it is necessary to keep in mind a sufficient anchorage of the reinforcement since the program does not check the reinforcement against the shear failure. A sudden increase of the normal force as shown in the figure suggests singularity in contact stresses and probable shear failure of the reinforcement. From that point of view the displayed results are misleading and essentially unrealistic.
In such a case, the reinforcement should be either removed from the analysis or ensure its sufficient anchorage as plotted in the figure.
Insufficiently anchored reinforcement
Correctly anchored reinforcement