NEWS AND BLOG

As a design-build firm specializing in industrial infrastructure, we understand a foundation’s critical role in manufacturing facilities’ structural integrity and long-term success. In this blog, we’ll explore the differences between deep and shallow foundations, their advantages and disadvantages, and key considerations for choosing the most suitable option for your project requirements.

Whether you’re embarking on a new construction project or contemplating foundation upgrades, this article is designed to equip you with practical insights that can guide your decision-making process. By applying these insights, you can ensure optimal performance for your manufacturing plant.

A foundation system plays a crucial role in any structure. Its primary function is to transfer forces from the structural system above to the earth below, providing stability to the structure. Understanding this role is fundamental to comprehending the significance of choosing the right foundation system for your project.

Foundations serve several purposes, including:

• To stabilize and support the structure.
• To resist differential settlement and increase the lifespan of the structure.
• Distribute loads from columns to a larger area.
• Redistribute uneven structural loads.
• Protect the structure from soil erosion beneath the structure.
• Provide lateral stability against lateral loads such as wind and seismic events.
• Provides stability against dynamic loads.

The type and magnitude of the load and the type of soil to which a foundation transfers force greatly influence the type of foundation system that may be used.

The function/requirements of the structure will determine the type and magnitude of the load it will impart to the foundation. A geotechnical investigation can determine the soil type and its load-resisting capability and may even recommend an appropriate foundation system.

There are two basic foundation systems: shallow foundations and deep foundations.

Shallow foundations on the Left. Deep foundations on the right.

Shallow foundations are placed near the ground surface and transfer the load at a shallow depth to the soil below that is of sufficient strength and stability. They are typically constructed using reinforced concrete. The bottom of the foundation must normally be located at or below the local frost line to prevent potential foundation and structural damage from frost heave.

Shallow Foundation Types:

• Isolated Footings – an individual footing that supports one column or post.
• Wall footing – a continuous footing that supports a wall.
• Combined Footings – an individual footing that supports two or more columns.
• Strap Footings – are a type of combined footing where one edge cannot extend beyond a property line. The foundations under the columns are built individually and connected by a strap beam, allowing them to work together.
• Mat Foundations – a large, thick foundation system that supports and distributes the forces of multiple loads.
• Retaining Wall Footings – a combined continuous wall and footing system that resists vertical and horizontal structure and soil loads.

Shallow Foundation Pros and Cons:

Pros:

• Typically requires less excavation, therefore reducing labor costs for excavation.
• Construction is relatively simple as the depth involved in placing is less.
• Usually, the width is less than the depth.
• Equipment required for construction is simple and less costly.
• Can be constructed in a short period of time.
• May be used where the bearing capacity of the upper layers of soil is high.
• Helps to reduce settlement if the soil is compressive.
• Less uncertainty in predicting the behavior of shallow foundations and supporting soil.
• Much less of an environmental impact than with deep foundations.

Cons:

• Cannot be used where the bearing capacity of the upper layers of soil is low.
• It may be difficult to use where the water table is high, and pumping water out of the excavation could be uneconomic.
• It can be challenging to use when the structure’s weight is high, and its load is unequally distributed.

Deep foundations are typically used when the earth near the surface does not have sufficient strength or stability to support the structure loads. The deep foundation system extends deep into the earth to engage stronger soil or bedrock to transfer the loads.

Deep Foundation Types:

• Pile Foundations:

Pile foundations are typically long, slender elements.

Materials Used: Timber, Reinforced Concrete, Precast, Steel (pipe or H-section).

Function: End Bearing Piles, Friction Piles, Sheet Piles, Mini-Piles, Helical Piles

Pile-type foundations are often combined with a pile cap system to engage multiple piles and resist vertical and horizontal forces.

• Pier/Caisson Foundations:

Pier or caisson foundations may be short or long but have a much larger cross-section than piles. They are often sized large enough to allow manual inspection of the pier excavation. They may or may not have belled ends to increase the bearing area of the pier.

Materials Used: Reinforced Concrete

Function: End Bearing Piers, Friction Piers

Deep Foundation Pros and Cons:

Pros:

• May provide superior stability, especially in areas with weak or variable soil conditions.
• Can provide increased load capacity for both compressive and tensile forces.
• Suitable for challenging soil conditions.
• Can be prefabricated off-site, allowing for efficient installation.
• Some deep foundation piles can displace and compact the soil, increasing the pile’s bearing capacity.

Cons:

• It can be challenging to know the actual length required in advance due to varying subsurface conditions.
• Subsurface stones and boulders can damage driven piles.
• Driven piles can produce vibrations that could negatively affect existing adjacent structures.
• Can be negatively affected by subsurface soil chemistry. There is a possibility of experiencing corrosion.
• Increased construction inspection may be required.
• Increased construction costs due to specialized construction equipment and skilled labor requirements.
• Installing deep foundations can be time-consuming and labor-intensive.
• Deep foundations can impact the environment. Groundwater and the surrounding ecosystem could be impacted by the use of large machinery and the disturbance of deeper soil layers.

In conclusion, choosing between deep and shallow foundations for manufacturing plants is crucial and requires careful consideration of various factors such as soil conditions, structural loads, and project requirements. By understanding each foundation type’s distinct characteristics, advantages, and limitations, project stakeholders can make informed decisions to ensure their manufacturing facilities’ long-term stability and success.

Whether opting for the simplicity of shallow foundations or the robustness of deep foundations, partnering with experienced design-build firms like ours can help navigate these complexities and deliver optimal solutions tailored to specific project needs. As you embark on your next manufacturing plant project, remember that a solid foundation is not just the basis of your structure—it’s the cornerstone of its longevity and resilience.

To learn more about Austin’s engineering capabilities, visit our design and engineering services page.

	Mark Price Supervisory Structural Engineer Call 440.544.2270 | Email Mark | View Profile