Oedometer tests according to DIN EN ISO 17892-5
Status: 10.12.2024
- Oedometer test with incremental loading (IL) including primary loading, unloading and reloading, creep test, swelling tests for clays
- Oedometer test with constant rate of strain (CRS)
- Oedometer test with cyclic loading
In the oedometer test (also one-dimensional confined compression test), a cylindrical soil sample is axially compressed while preventing radial deformation. This test yields the stiffness Es, the compressibility coefficient av, the compression index Cc, the swelling index Cs and other soil properties. If the temporal progression of the settlement during a load stage is also recorded, the creep coefficient and the consolidation coefficient can also be determined. The permeability of the soil can be derived.
The soil sample is cut out of an undisturbed sample using a metal ring or is installed in a metal ring with a specific density or consistency. Filter plates are placed on the flat, machined end surfaces of the sample to drain the pore water. In the compression device or oedometer, the cylindrical soil sample with a diameter of 70 mm and a height of 20 mm is gradually loaded and unloaded in the axial direction, with the primary settlements having to subside at each load stage. The vertical deformation of the sample is measured. When the sample is unloaded, the uplift of the sample is recorded. The measured deformations and the associated effective stresses are shown in the pressure-settlement diagram or pressure-pore number diagram. The slope of the tangent to the pressure-settlement curve is called the stiffness modulus. The compression coefficient and threshold coefficient are determined from the course of the pressure-void ratio curve.
The pressure-settlement lines and pressure-void ratio lines provide the one-dimensional deformation under a vertical load with one-dimensional (axial) drainage. Settlements of structures are calculated using the stiffness modulus. The temporal progression of the settlements can be estimated mathematically using the time-settlement line.
