Here is what i do to solve this:

Imagine you have your 31.4 pipeline buried completely straight and horizontal and at an infinite length. At a certain distance from the point where it buries, the effect of the temperature and above ground stresses will be negligible. This means that all the rest of the buried pipeline at a bigger distance than this, does not suffer the effect of the above ground portion of the pipeline. Then your simulation will have to be done just to that distance. There is no sense in doing you simulation at bigger length. To find that length, put that "perfect pipeline" model in Caesar with the soil characteristics and run it. It will be easy because it is a straigth horizontal line! Then you will see a point where the effect is so little that it can bu cut there. Then simulate your model with the right coordinates, only to that length. You will have to input all points to the right geometry for that portion of your pipeline. Considering that your real pipeline is not completely straight and horizontal, the above ground effect will be in a shorter portion of your pipeline. You will be able to see it in you analysis. I hope this helps.