You can consider the old Schnackenberg's article "How to calculate stress in above/below ground transition".
The key parameter considered in article is "the longitudinal resistance of the soil that needs to be known".
In fact, Schnackenberg's model is a simple linear one, where the stress difference between "fully restrained" and "unrestrained" points (multiplied by pipeline metal sectional area) generates a tendency to "elongate" to the ends of pipeline (typically toward pig stations).
Fortunately, this reference article is still included in "Pipeline rules of thumb" handbook.

For your case, the results based on this article are only a rough approximation.
Actually, your model shall return a correct value of the displacement when VAL is established in a correct position; this may be checked by performing few trials that would convince you that points with zero displacements are indeed where they are supposed to be.