Project Overview
This tutorial focuses on the simulation of a Consolidated Drained (CD) triaxial test using the Abaqus software. This example is based on Example 5.6 from the Sam Helwany book.
The numerical results obtained from Abaqus are compared with the corresponding results presented in the book to evaluate the accuracy of the numerical simulation.
Model Description
The soil specimen is modeled as a cylindrical sample with a diameter of 5 cm and a height of 5 cm.
The CD triaxial test is performed in two main steps. In the first step, the soil specimen is subjected to a uniform confining pressure. In the second step, a vertical load is applied to the specimen until failure.
Confining Pressure
In the first step, a uniform confining pressure of 210 kPa is applied to the soil specimen.
The confining pressure is applied to the top surface and the lateral surface of the soil specimen to establish the initial stress state before shearing.
Shearing Step
In the second step, the specimen is subjected to vertical loading until failure. This step represents the shearing stage of the consolidated drained triaxial test.
The duration of the shearing step is set to 109 seconds. A very long analysis time is considered because the test is performed under drained conditions and the loading rate must be sufficiently low.
Drainage Conditions
The analysis is performed under drainage conditions. The top and bottom surfaces of the soil specimen are considered permeable, allowing water to drain through these surfaces during the analysis.
These drainage conditions allow the pore water pressure generated during loading to dissipate and reproduce the conditions of a consolidated drained triaxial test.
Deviator Stress vs. Axial Strain
One of the main objectives of this simulation is to obtain the relationship between deviator stress and axial strain.
The curve obtained from Abaqus is compared with the corresponding deviator stress versus axial strain curve from the Sam Helwany book.
Volumetric Strain vs. Axial Strain
The volumetric strain is also investigated during the shearing stage. The volumetric strain is calculated from the normal strains in the three principal directions:
εv = εx + εy + εz
The volumetric strain versus axial strain relationship obtained from Abaqus is compared with the corresponding result from the Sam Helwany book.
Comparison with Sam Helwany Book
The numerical results obtained from Abaqus are compared with the results presented in Example 5.6 of the Sam Helwany book.
The comparison includes both the deviator stress versus axial strain relationship and the volumetric strain versus axial strain relationship.
What You Will Learn
- How to model a cylindrical soil specimen in Abaqus.
- How to simulate a Consolidated Drained (CD) triaxial test.
- How to apply a confining pressure of 210 kPa.
- How to define the consolidation stage.
- How to perform the shearing stage under drained conditions.
- How to define permeable surfaces for drainage.
- Why a very long analysis time is required for drained loading.
- How to obtain deviator stress versus axial strain.
- How to calculate volumetric strain from the three normal strains.
- How to compare Abaqus results with reference results.
Key Features
- Consolidated Drained (CD) triaxial test.
- Cylindrical soil specimen.
- 5 cm diameter and 5 cm height.
- 210 kPa confining pressure.
- Two-step analysis.
- Long-duration shearing step.
- Drained loading conditions.
- Permeable top and bottom surfaces.
- Deviator stress versus axial strain.
- Volumetric strain versus axial strain.
- Comparison with Sam Helwany Example 5.6.
- Free Abaqus tutorial.
Project Information
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