Module 2: Piling Techniques and Methods 

1. Driven Piling Methods

Driven piles are installed by hammering pre-formed piles (concrete, steel, or timber) into the ground using impact or vibratory hammers.

Key Features:

• Displacement Piles – Soil is pushed aside rather than removed.

• Types of Driven Piles:

• Precast Concrete Piles – Reinforced for high load-bearing capacity.

• Steel H-Piles & Tube Piles – Used in dense or rocky soils.

• Timber Piles – Common in marine and temporary works.

• Installation Equipment:

• Drop Hammers – Gravity-driven impact.

• Diesel Hammers – High-energy impact for hard soils.

• Vibratory Hammers – Best for loose or sandy soils.

• Advantages:

• Fast installation.

• No need for soil removal.

• Immediate load-bearing capacity.

• Disadvantages:

• Noise and vibration concerns.

• Risk of pile damage during driving.

2. Bored Piling Techniques

Bored piles are constructed by drilling a hole and filling it with reinforced concrete.

Key Features:

• Non-Displacement Method – Soil is excavated rather than displaced.

• Types of Bored Piles:

• Small-Diameter Bored Piles (≤600mm) – For light structures.

• Large-Diameter Bored Piles (≥900mm) – For heavy loads (bridges, high-rises).

• Installation Process:

• Drilling – Using augers or rotary rigs.

• Temporary Casing – Prevents hole collapse in loose soils.

• Bentonite Slurry – Stabilizes boreholes in wet conditions.

• Reinforcement Cage Insertion – For structural strength.

• Concrete Pouring – Tremie method ensures no segregation.

• Advantages:

• Minimal vibration.

• Suitable for deep foundations.

• Disadvantages:

• Slower than driven piling.

• Requires spoil removal.

3. Continuous Flight Auger (CFA) Piling

A fast, efficient method where a hollow-stem auger drills and simultaneously pumps concrete.

Key Features:

• Process:

• Auger Drilling – Continuous spiral removes soil.

• Concrete Injection – Pumped through the hollow stem as the auger withdraws.

• Reinforcement Placement – Cage inserted while concrete is wet.

• Advantages:

• No temporary casing needed.

• Fast installation (ideal for urban sites).

• Disadvantages:

• Limited depth (typically <30m).

• Requires precise concrete flow control.

4. Micro-Piling Applications

Micro-piles (or mini-piles) are small-diameter (100-300mm), high-strength piles used in restricted spaces or weak soils.

Key Features:

• Installation Methods:

• Drilled & Grouted – Uses a small rig and cement grout.

• Percussive Drilling – For rocky or hard strata.

• Applications:

• Underpinning existing foundations.

• Slope stabilization.

• Retrofitting structures.

• Advantages:

• Minimal vibration.

• Works in low-headroom conditions.

• Disadvantages:

• Lower load capacity than conventional piles.

5. Sheet Piling Installation

Used for retaining walls, cofferdams, and flood defenses, typically made of steel or vinyl.

Key Features:

• Installation Methods:

• Vibratory Hammer – Most common for steel sheets.

• Press-In Method – Silent installation (urban areas).

• Impact Hammer – For dense or rocky ground.

• Interlocking Design – Ensures a continuous barrier.

• Advantages:

• Quick installation.

• Reusable (steel sheets).

• Disadvantages:

• Noise/vibration in urban areas.

• Limited depth in hard soils.

Conclusion:

Each piling method has specific applications based on soil conditions, load requirements, and site constraints. Understanding these techniques ensures the correct choice for safe and efficient foundation construction.