Oedometry

Oedometry is a branch of mechanics that studies the deformation of porous materials under applied loads, specifically focusing on volume changes. The term is derived from the Greek words "oedema," meaning swelling or puffiness, and "metron," meaning measure. This field is particularly relevant in soil mechanics, but also finds applications in other areas involving deformable porous media such as concrete, biological tissues, and geological formations.

The fundamental principle of oedometry involves confining a sample of the material in a cylindrical ring, preventing lateral expansion, and then applying a load to the top surface. The resulting settlement or compression of the sample is measured. This controlled environment allows for the isolation of vertical deformation and the study of how pore fluid pressure, material properties, and applied stress interact to cause volume changes.

Key parameters derived from oedometric tests include the constrained modulus, which quantifies the material's stiffness under these specific conditions, and the coefficient of consolidation, which describes the rate at which excess pore water pressure dissipates and consolidation occurs. These parameters are crucial for predicting the long-term settlement of structures built on compressible soils and for understanding the behavior of saturated porous materials under stress. The oedometric test is a standard laboratory procedure used extensively in geotechnical engineering.