Geotech: Deep Foundation

Introduction

• Today's class is the last in the crash course on Geotech.
• A new topic will start tomorrow.
• Today we will discuss deep foundation, pile foundation, and soil exploration.

Deep Foundation

• When to use: When the shallow depth soil is weak and there are stronger deposits deeper.
• Types:
  • Pile Foundation
  • Well Foundation
  • Pier Foundation
• Pile Foundation: Load transfer occurs through a pile cap, column, and its medium.

Pile Foundation

• Classification:

  • End Bearing Piles: Most of the load is transferred by point bearing.
  • Friction Piles: Most of the load is transferred by friction.
  • Batter Piles: For horizontal load transfer.
  • Compression Piles: To compact loose sand.
  • Tension Piles: To carry tension force.

• Pile Load Capacity:

  • Static pile load formula
  • Driven pile formula
  • Pile load test
  • Correlation with penetration test

• Failure Criteria:

  • Safety against failure of soil
  • Safety against excessive settlement

Group Action of Piles

• Piles are always used in a group.
• Group efficiency is defined.
• Minimum Spacing code recommendations:
  • For point bearing: 2.5D
  • For friction: D
  • Resting on rocks: D

Pile Driving Formula

• Energy imparted = Work done by pile
• Engineering News Formula:
  • Q = (W * H) / (S + C)*

Pile Load Test

• Vertical pile load test
• Initial and routine test

Negative Skin Friction

• When it occurs: In built-up deposits
• Impact: Harmful for piles

Soil Exploration

• Augers, Boring Methods, Sampler
• Key Parameters: Inside clearance, outside clearance, area ratio

Conclusion

• In today's class, we reviewed deep foundation and pile foundation in detail.
• A new crash course will begin tomorrow.

Important Notes:

• Ensure you understand the effects and precautions of negative skin friction well.
• The formulas for pile driving and load capacity are important, make sure to revise them.
• Pay attention to the various parameters of soil exploration, especially sampler design.