Please read soil consolidation and also use FEM.

First of all, you must understand that soil settlement is vertical displacement of the material, produced by vertical strain in soil. In general, settlements happen during whole soil history (by vertical geostatic stresses from self weight), and this process is called consolidation. What is the most important is the moment of time from which we MEASURE settlements, and of course we cannot do it during total soil history. We assume that, in general, consolidation process is finished before our buildings are constructed.

When you build your building, you apply additional vertical loading to the soil and you initiate additional consolidation of the soil - settlements we discuss are then additional settlements of the soil as the result of additional vertical loading.

There are different methods that can be used to calculate and predict soil settlements below foundations, and they are described in many Soil Mechanics and Foundation Design books (for example, J. Bowles - Foundation Analysis and Design). But the only way to correctly measure and identify settlements of the buildings in-situ is surveying, and it must start at the moment of applying additional vertical loading to the soil (from the start of the construction).