An Introduction to Soil Settlement and Expansion for Professional Engineers

Settlement is the result of three primary mechanisms: (1) immediate distortion that occurs in response to the application of a new load, (2) consolidation, which is compression of the soil skeleton in response to changes in effective stress, and (3) secondary compression, which is rearrangement of the soil structure under constant effective stress. All three mechanisms will be explained in more detail in later sections. In saturated fine-grained soils, the settlement associated with the three mechanisms can be distinguished and separated for the practical purpose of estimating settlement magnitude. This separation is possible because these soils have low hydraulic conductivity and relatively high compressibility, which causes consolidation to occur over a measurable period of time. The processes and magnitudes of settlement typically associated with fine-grained soils are summarized. Coarse-grained soils are much less compressible than fine-grained soils and have higher hydraulic conductivity. Because of these characteristics, consolidation occurs very quickly and can be difficult to separate from immediate deformation. Much of the compression of coarse-grained soil is related to particle rearrangement under changed stress. Vibrations from earthquakes, blasting, or machinery can also cause settlement of coarse-grained soil. Submergence and soaking of coarse-grained soils, particularly fill materials, can lead to settlement as discussed.

Pages: 83, Paperback, Independently published