Settlement calculations in geology rely on data obtained from which laboratory test?

Settlement calculations in geology primarily rely on data obtained from consolidation tests because these tests provide critical information about how soils behave under load over time. The consolidation test, often performed using a oedometer, measures the volume change of soil when subjected to increased pressure. This is crucial for understanding how much settlement can occur when structures are built on a given soil type.

During the consolidation process, the pore water pressure within the soil changes, leading to an expulsion of water and subsequent reduction in volume. The results of these tests yield parameters such as the coefficient of consolidation and the compression index, which are essential for predicting the rate and magnitude of settlement that will occur as loads are applied over time.

In contrast, tests such as direct shear focus on soil strength under shear stresses, permeability assesses the soil's ability to transmit water, and compaction tests evaluate changes in soil density when subjected to mechanical effort. While these tests are important for various aspects of geotechnical engineering, they do not directly assess the time-dependent settlement that consolidation tests do. Thus, the consolidation test is the key method for accurately predicting settlement in geological studies.