In engineering practice, soil parameters are obtained from one or more laboratory tests. In order to perform the best calculation, these soil parameters have to be translated into input parameters for the constitutive model used, taking into account the possibilities and limitations of the constitutive model. Most parameters for the constitutive models can be determined directly from standard laboratory tests such as triaxial test and oedometer test. However, due to the complexity of the models, it is recommended to not simply accept the parameters determined from those tests, but to actually model the tests and see if the parameters found actually give a proper representation of the real laboratory test results within the limits of the constitutive models. For this purpose, the Soil Test wizard is available with which in a simple manner laboratory tests can be simulated without the need for making a finite element model.

[Soil Test Set Name]

Define the set name of soil test to simulate.

[Method]

Select the test that will be simulated. The test options available are Tri-axial, Oedometer, CRS, DSS and General.

• Tri-axial Test

In a triaxial test, stress is applied to a sample of the material being tested in a way which results in stresses along one axis being different from the stresses in perpendicular directions. This is typically achieved by placing the sample between two parallel platens which apply stress in one direction, and applying fluid pressure to the specimen to apply stress in the perpendicular directions.

With the triaxial test, it is possible to test soil properties while controlling the stresses applied in the vertical and horizontal directions relative to the specimen.

• Oedometer Test

Oedometer test is designed to simulate the one-dimensional deformation and drainage conditions that soils experience in the field. To simulate these conditions, rigid confining rings are used to prevent lateral displacement of the soil sample. Porous stones are placed on the top and bottom of the sample to allow drainage in the vertical direction.

With the oedometer test, it is possible to define a one-dimensional compression test for soil models.

• CRS (Constant Rate of Strain) Test

In a Constant Rate of Strain test (CRS test), it is possible to gradually apply a load to a soil model by increasing the displacement of a pressure cylinder at a constant rate.

In a CRS test, it is possible to gradually apply a load to a soil model by increasing the displacement of a pressure cylinder at a constant rate.

• DSS (Direct Simple Shear) Test

The DSS test can be used to determine the shear strength of a soil model.

• General Test

The general soil test can be used as a customisable soil test mode. The user can define arbitrary stress and strain conditions.

[Material]

Define the soil material properties.

[Initial Stress]

Define the initial stress. In case of ‘General’ type, it is possible to define the stresses of each direction.

[Boundary Condition]

The boundary condition is decided by the test method. In case of ‘General’ type, it is possible to restrain the stress / strain conditions of each direction. This is an initial condition which cannot be changed to the construction stages (applies to all stages).

[Stage Name]

Define the different stages of the test.

[Advanced Setting]

Define the details for analysis.

[Analysis]

Start the calculation for the selected soil tests.

[Show Graph]

The results of the test are displayed in the predefined diagrams in the graph window.

Stage

Each stage is defined by a number of steps (Inc.), a duration (in units of time) and a applied stress or strain increments. The given stress or strain increment will be reached at the end of the given duration in the given number of steps. A negative stress or strain increment means additional compression, whereas a positive stress or strain increment means unloading or tension.

Analysis

Define the convergence criteria of analysis.

Output

Define the graph setting. You can select the configuration of diagrams to display.