1) Consolidation is the process by which a saturated soil reduces in volume by expelling water from its pores under an applied load over time. 2) The one-dimensional consolidation theory proposed by Terzaghi makes assumptions that the soil is fully saturated, uniformly distributed loading, drainage occurs only vertically, and soil is homogeneous and isotropic. 3) The main difference between compaction and consolidation is that compaction involves expelling air from soil pores, while consolidation involves expelling water.