Hi everyone,

I’m working on a lateral displacement-controlled analysis of a rigid caisson embedded in soil using Abaqus/Standard. Previously, I applied the lateral load using a kinematic coupling constraint at the top of the caisson, and the load–displacement response was smooth and realistic.

However, in my latest model, when I try to use the same kinematic coupling technique between the caisson top (a reference point) and the circular surface at the head, the curve becomes unstable, jagged, or sometimes even flat after an initial jump.