ASTM D3080
Full Name
ASTM D3080 – Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions
Scope
ASTM D3080 outlines a test method for determining the consolidated drained shear strength of soil. This test is essential for understanding a soil’s behavior under load, particularly in situations where long-term consolidation and drainage are expected, such as the foundation of a structure.
The direct shear test involves subjecting a soil specimen to a controlled vertical load (normal stress) while shearing it along a predetermined horizontal plane. The test measures the shear force required to cause failure at different normal stress levels.
Key aspects of ASTM D3080:
- Purpose: to determine the consolidated drained shear strength of soil.
- Principle: the test simulates field conditions where soil has consolidated under applied load and excess pore water pressure has dissipated.
- Procedure:
- A soil specimen is placed in a shear box with two halves.
- A predetermined normal stress is applied, and the specimen is allowed to consolidate (drain).
- One half of the box is moved horizontally at a controlled rate, shearing the specimen.
- Shear force and horizontal displacement are continuously measured.
- Data Analysis: the test results in shear stress versus horizontal displacement curves for each normal stress. These curves are used to determine the peak shear strength at each normal stress.
Applications:
- Determining the shear strength parameters of soil (cohesion and angle of internal friction).
- Evaluating the stability of slopes and embankments.
- Designing foundations for structures.
- Assessing the bearing capacity of soil.
Limitations:
- The test forces failure along a predetermined plane, which may not represent the weakest plane in the field.
- The stress distribution within the specimen is not uniform, making it unsuitable for determining stress-strain relationships or shear modulus.
- The test may not be suitable for soils with large particles, as they can influence the test results.
Understanding the consolidated drained shear strength of soil is crucial for various geotechnical engineering applications. The ASTM D3080 standard provides a standardized and reliable method for determining this property, ensuring the safety and stability of structures built on soil.
ASTM D3080 Accredited Laboratory
Applied Testing & Geosciences, LLC is accredited for performing tests using the ASTM D3080 standard.
Contact us today to learn more about our services and how we can help you with your next project.
Resources
Keywords
shear strength; direct shear test; consolidated drained; mohr strength envelope; shear stress; shear displacement; normal load; strain rate; compacted specimens; undisturbed; soil; specimen; test method; apparatus; displacement