Shear failure in soil frictional cohesive strength | Summary and Q&A

TL;DR

Shear failure in soil occurs when the shear stress induced by compressive load exceeds the shear strength of the soil, and it can be expressed using the Mohr-Coulomb equation.

Key Insights

• 📶 Shear failure in soil occurs when shear stress exceeds shear strength due to compressive load.
• 😑 The Mohr-Coulomb equation expresses shear strength in terms of cohesion, angle of internal friction, and effective stresses.
• 💦 Cohesion and angle of internal friction depend on factors like water content, drainage conditions, and testing conditions.
• 📶 Some soils have no cohesion but derive shear strength from intergranular friction (cohesionless or frictional soils).
• 🔺 Purely cohesive soils have cohesion but no angle of shearing resistance.
• 🔺 Composite soils can exhibit both cohesion and angle of shearing resistance.
• 🎮 Effective stresses, rather than total stresses, control shear strength.

Transcript

hello everyone in this video we are going to discuss shear failure in soil of frictional cohesive strength shear strength of the soil is its maximum resistance to shear stresses just before the failure shear stresses are developed when soil is subjected to direct compression stresses can also be developed due to direct tension but tensile strength ... Read More

Questions & Answers

Q: What is shear failure in soil?

Shear failure in soil occurs when the shear stress induced by compressive load exceeds the shear strength of the soil, leading to relative movement of particles.

Q: How is shear strength of soil expressed?

The shear strength of soil is expressed using the Mohr-Coulomb equation, which relates the shear strength to cohesion, angle of internal friction, and effective stresses.

Q: Are cohesion and angle of internal friction fundamental properties of soil?

No, they are not fundamental properties. They depend on factors like water content, drainage conditions, and testing conditions, which influence the parameters of cohesion and angle of internal friction.

Q: What are some examples of soil types with different characteristics?

Cohesionless or frictional soils, such as sands and gravels, derive their shear strength from intergranular friction. Saturated clays under undrained conditions can exhibit purely cohesive behavior, with no angle of shearing resistance.

Summary & Key Takeaways

• Shear failure in soil happens when the shear stress caused by compression exceeds the shear strength of the soil.

• The shear strength of soil is expressed using the Mohr-Coulomb equation, which considers cohesion, angle of internal friction, and effective stresses.

• Factors such as water content, drainage conditions, and testing conditions influence the parameters of cohesion and angle of internal friction.