You are aware that construction of any type of structure takes sometime. Pressure due to the building will be applied gradually and not instantaneously. Excavation for the construction of the foundation is essential. This results in the release of pressure. Hence, original pressure is reached gradually as the construction progresses. Later on, it gradually increases the pressure. Figure shows the rate of loading as the construction activity progresses. The expansion and recompression due to excavation and construction upto ground level is normally neglected. The loading period is considered as effective when the construction advances above ground level.

From Figure, it is ,clear that finishing rate of load increment is considerably decreased. Hence, effective loading period is to be considered.