Difference Between Shallow and Deep Foundations in Construction

A great construction always starts from the bottom. Knowing the difference between shallow and deep foundation systems is vital for safe, long-lasting, and cost-efficient construction. Foundations depend on the loads, the height, the design of the structure, and the soil conditions. The goal of this post is to help builders, engineers, and homeowners know more about shallow foundation, deep foundation, and the advantages, applications, types of both, and differences to make better decisions.

What Is a Foundation in Construction?  

A foundation is the very bottom of a structure that transfers the weight of the building to the ground safely. There are many foundation types in construction, and foundations are divided into two main groups.

• Shallow foundations
• Deep foundations

The correct foundation will make the structure safe and stable, and help the building last longer.

What Is a Shallow Foundation?  

A shallow foundation transfers the load of the structure to the soil at a low depth. It is appropriate for use where the soil in the upper layers has enough bearing capacity to hold the weight of the building. The shallow foundation is:

• Depth is equal to or less than the width

• Cost and construction are straightforward
• Favourable for smaller buildings
• Good soil conditions needed

A shallow foundation is the most common for residential houses, small commercial buildings, and small-load construction.

Types of Shallow Foundation  

Types of shallow foundations need to be elaborated for proper selective choice based on the sites.

• Isolated Footing: Supports one column and is most commonly used where the columns are widely spaced.

• Combined Footing: Supports two or more columns when they are placed closely together

• Strip Footing: Used for load-bearing walls and walls of long buildings.

• Raft or Mat Foundation: This is for when the soil is weak, and therefore, covers the whole foundation area, i.e, balances the loads and is used quite a lot.

All types of shallow foundations are economical and require less time to build.

Advantages of Shallow Foundation  

• Low price
• Simple to design and execute
• Takes less time
• Little injury to the area
• Simple to monitor and fix

These profound advantages are, however, clouded by the fact that shallow foundations are not suitable for weak soil and heavy loads.

Limitations of Shallow Foundations   

• Cannot support tall buildings
• Loose soil increases the risk of settlement
• Low load-bearing capacity
• Sensitive to soil moisture fluctuations

This is where deep foundation systems are necessary.

What Is a Deep Foundation?   

A deep foundation transfers building loads down to the stronger soil or rock layers. It is used when the surface soil is too weak or when the loads are extremely heavy.

Key Characteristics of Deep Foundation   

• Depth is more than the width
• Used on heavy and tall buildings
• Works well with poor soil
• Needs special construction techniques

Deep foundations are common in bridges, high-rise buildings, flyovers, and industries.

Types of Deep Foundations  

There are a number of types of deep foundations based on the structure and soil conditions.

1. Pile Foundation  

Long, cylindrical columns that are driven deep into the soil. Loads can be transferred through friction or end bearing.

2. Pier Foundation   

Large-diameter cylindrical foundations are used when there is hard soil at a moderate depth.

3. Caisson Foundation   

This is used in underwater or riverbed construction, such as bridges and dams.

These types of deep foundations provide a high load-bearing capacity and great stability.

Advantages of Deep Foundations  

• Appropriate for weak or waterlogged soil
• Supports heavy structural loads
• Lower settlement risks
• Appropriate for tall buildings and large infrastructure projects

Limitations of Deep Foundations    

• Increased construction cost
• Requires skilled labour and sophisticated machinery
• Extended construction duration
• Difficult to inspect and maintain

Regardless of cost, deep foundations are critical for large projects to ensure safety.

Difference Between Shallow and Deep Foundation   

Below is a clear comparison showing the difference between shallow and deep foundation systems:

This comparison clarifies the difference between shallow foundation and deep foundation systems in terms of application and performance.

Shallow Foundation vs Deep Foundation: Which One to Get?  

This will be decided based on:

• Soil bearing capacity
• Type of structure
• Height of the building
• Load intensity
• Weather conditions

If it's a house or a small building, shallow foundations will be just fine. Deep structures like towers, bridges, or even industrial plants require deep foundations.

Importance of Quality Materials Used on the Foundation   

For any type of foundation, there is a need to use quality material. For example, the best quality TMT bars in India will:

• Increase tensile strength
• Improve resistance to earthquakes
• Increase bonding to concrete
• Last longer

For both the shallow and the deep foundation, the TMT bars need to be of a higher grade.

Types of Foundation and Safety During Construction  

When it comes to foundation types in construction, the most important factors are the design and the choice of the material. The wrong foundation choice can lead to:

• Cracks in the structure
• Uneven settlement
• Short lifespan of the building
• Safety problems

With engineering knowledge, the right equilibrium can be met between the cost and the safety.

Applications Across Types of Construction  

Depending on the type of construction, the required foundation systems differ. Below is a summary of the various systems put in specialised construction:

• Residential buildings → Shallow foundation
• Commercial complexes → Raft or pile foundation
• High-rise towers → Deep foundation
• Bridges and flyovers → Pile or caisson foundation

The right type of foundation is the one the structure will be built.

Also Read : Guide to Different Types of Steel Reinforcement Bars

Conclusion  

In construction planning, knowing the difference between shallow and deep foundations is crucial. For lightweight structures, shallow foundations are economical and a better ground choice; deep foundations become a better structure choice for very tall and heavy buildings. Supported structures with a solid ground become coupled with a poor soil condition, proper core and load on the structure, and structure scale and options. Taking the right foundation type, builders can be guaranteed safety and durability, lasting performance of the structure, and performance on all levels.

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