chapter  Chapters 6
31 Pages

Compressibility and settlements

ByJ.A.R. Ortigao

This chapter deals with soil compressibility and settlements in conditions of no significant lateral deformation. As an example, consider the embankment foundation. It has width B and depth D of the compressible layer and B >> D. Points A and B in the foundation present the following behaviour. Point A is below the centre of the loaded area, where there is no shear stress. Volumetric strains at this location will occur without significant change in shape and with no lateral deformation. The chapter focuses on the behaviour of point A subject to vertical deformation only. Therefore, settlements due to sand compressibility are normally neglected in foundation design. In order to look at the volumetric strains undertaken by a soil sample, an equipment developed by Terzaghi known as the oedometer is used. Determination of overconsolidation stress value is very important since large soil deformation occurs when its value is exceeded.