Shear Failure Mechanisms in Soils
What are general shear failure and local shear failure in soils?
General shear failure and local shear failure refer to different failure mechanisms in soils under load. Which type of soil is prone to general shear failure and which type is more likely to experience local shear failure?
How do these two failure mechanisms differ in terms of failure planes and post-failure volume changes?
Answer:
General shear failure and local shear failure are distinct mechanisms of failure that occur in soils under loading conditions. General shear failure is typical in dense or stiff soils, while local shear failure is more common in loose or soft soils.
General shear failure is characterized by clear failure planes and significant volume changes post failure. In contrast, local shear failure involves less distinct failure planes and minor post-failure volume changes.
Explanation:
In soil mechanics, general shear failure and local shear failure illustrate different behaviors of soils under load. General shear failure typically occurs in dense or stiff soils where there is a clear failure plane that develops as the load increases. This type of failure is associated with significant post-failure volume changes due to the abrupt release of stress.
On the other hand, local shear failure is more prevalent in loose or soft soils that deform more uniformly under load. The failure planes are not as defined, and the volume changes after failure are minimal compared to general shear failure. The stress-strain curve in local shear failure keeps increasing without a clear peak, indicating ongoing deformation of the soil.
Understanding the distinction between general shear failure and local shear failure is crucial in analyzing the stability of soil structures and preventing potential failures. By identifying the type of soil and its behavior under load, engineers can make informed decisions to ensure the safety and longevity of civil engineering projects.