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Writer's pictureJosh Hric

Everything You Need to Know About Engineered Retaining Walls

Updated: Jul 14



Introduction

Retaining walls play an important role in various construction projects, providing stability and preventing soil erosion. Among the different types of retaining walls, engineered retaining walls stand out for their strength, durability, and ability to withstand lateral pressure. In this essential guide, we will explore the components, types, and the engineering process behind engineered retaining walls.

Understanding Engineered Retaining Walls

Engineered retaining walls are designed by structural engineers to provide stability and prevent soil erosion. These walls are necessary when there is a need to retain soil or shape the land. The design of an engineered retaining wall takes into consideration factors such as soil type, site conditions, and the height of the wall. By using the principles of retaining wall design, structural engineers make certain that the wall can withstand soil pressure and other external forces to maintain its stability and safety.

When a Retaining Wall Needs Engineering

A retaining wall may require engineering when it exceeds a certain height. Local building codes and regulations often determine the height at which a retaining wall must be engineered. Generally, if the top of the wall is higher than a specified limit, a building permit and the involvement of a structural engineer are required. These regulations are necessary to ensure the safety of the structure and prevent potential hazards. It is important to consult local codes and regulations before constructing a retaining wall to determine if engineering is required.

The Importance of Engineered Solutions for Stability

Engineered retaining walls are also important for maintaining stability in various construction projects. These walls are designed to withstand the soil pressure exerted on them and prevent soil erosion. Without proper engineering, retaining walls may fail under the pressure of the soil, resulting in structural damage and potential hazards.

Key Components of Engineered Retaining Walls

The key components of engineered retaining walls include design engineers, civil engineers, and concrete walls. Design engineers play a crucial role in designing the retaining wall structure, taking into consideration factors such as site conditions and soil type. Civil engineers oversee the construction process and ensure adherence to engineering specifications. Concrete walls are commonly used in engineered retaining walls due to their strength and durability.

Materials Commonly Used in Engineered Retaining Walls

Engineered retaining walls utilize a variety of materials to ensure strength and durability. One common material used is gabion walls, which are wire mesh containers filled with stones or rocks. These provide stability and allow for water drainage. Concrete blocks are another commonly used material due to their strength and versatility. They can be stacked to create a solid wall structure. Gravel is often used as backfill material to provide drainage and prevent water accumulation behind the wall.

Design Principles for Longevity and Safety

Design principles for engineered retaining take into account longevity and safety. These principles take into consideration factors such as site conditions, wall height, and lateral forces. Site conditions, such as soil type and slope, determine the design specifications of the retaining wall. Wall height is an important factor as taller walls require additional reinforcement. Lateral forces, such as soil pressure, must be considered to make certain the wall is stable.

Types of Engineered Retaining Walls

There are different types of engineered retaining walls, each with its own unique design and construction methods. Cantilever retaining walls are supported by footings and rely on the weight of the wall to resist soil pressure. Gravity walls use their weight to hold back the soil. Anchored wall systems utilize geogrids or grids to reinforce the wall and increase stability. Each type of engineered retaining wall has its advantages and is used for different applications. Understanding these types can help in choosing the right solution for specific project requirements.

Gravity Walls and Their Mechanism

Gravity walls rely on their weight to resist soil pressure. The mechanism behind gravity walls involves using the friction between the wall and the soil to provide stability. The setback, or the angle at which the wall leans into the soil, is an important design consideration for gravity walls. The setback helps to distribute the soil pressure and prevent the wall from toppling over. By utilizing the force of gravity and employing the right setback, gravity walls can effectively hold back the soil and provide stability for some construction projects.

Cantilevered Walls: Structure and Application

Cantilevered walls are a common type of engineered retaining wall. These walls are supported by footings and rely on the principle of cantilever to resist soil pressure. The footing provides a stable base for the wall, while the cantilever design allows the wall to extend outwards without additional support at the top.

Anchored Wall Systems Explained

Anchored wall systems are a type of engineered retaining wall that uses geogrids or grids to reinforce the structure. These systems involve embedding the geogrid into the soil behind the wall. The geogrid or grid extends past the point where the soil would naturally slide, providing additional reinforcement and preventing soil erosion. Anchored wall systems are ideal for situations where high lateral forces are expected.

The Engineering Process Behind Retaining Walls

The engineering process behind retaining walls involves several steps. It starts with a site analysis, which includes evaluating soil conditions and determining the correct retaining wall design. Qualified engineers, such as structural engineers and design engineers, can play an important role l role in this process.

Site Analysis and Soil Considerations

Site analysis and soil considerations are important parts of the engineering process for retaining walls. Site conditions, such as slope and proximity to other structures, are evaluated to determine the correct design and construction methods. Soil type is another important factor, as different soil types have different properties and behaviors. The engineering team assesses the soil conditions to ensure the retaining wall is designed to withstand the specific soil pressures and potential risks. Excavation may be required to prepare the site and create a stable foundation for the retaining wall.

Load Calculations and Material Selection

Engineered retaining walls are designed to withstand forces exerted by wind, earth, fluids, and other external factors. Load calculations play a crucial role in determining the dimensions and materials required for the walls. It involves considering factors such as the height of the wall, soil type, and the magnitude of the lateral force. By accurately calculating the load, engineers can select the appropriate materials, such as reinforced concrete or modular blocks, in order to maintain the wall's structural integrity. Material selection also takes into account factors such as durability, cost-effectiveness, and aesthetics. It is important to choose materials that can withstand the specific environmental conditions and provide the necessary support to retain the soil.

Common Challenges and Solutions

Building engineered retaining walls can present challenges. Common challenges include drainage issues, lateral forces, and erosion. Poor drainage can lead to water accumulation behind the wall, increasing the weight of the soil and potentially causing failure. To address this, drainage systems such as weep holes or pipe drains can be incorporated into the design. Lateral forces exerted by the soil can cause the wall to slide or overturn. Building the wall with sufficient width and weight, as well as using appropriate reinforcement, can mitigate these forces. Erosion can also undermine stability. Implementing proper erosion control measures, such as backfilling and grading, can help protect the wall from erosion damage.

Installation Tips for Engineered Retaining Walls

Proper installation is crucial for the performance and longevity of engineered retaining walls. Hiring professionals who specialize in retaining wall design services can ensure that the installation is done correctly. Before installation, it is important to assess the site conditions, including soil type and slope stability. Following the manufacturer's guidelines and specifications for the selected wall materials is essential. Adequate excavation, footing preparation, and backfilling techniques should be used for a solid foundation.

Professional Advice on Avoiding Common Pitfalls

To avoid common pitfalls in the design and construction of engineered retaining walls, it is important to seek professional advice and adhere to building codes and regulations. Here are some key considerations:

  • Consult with a qualified engineer or structural engineer to ensure that the design meets the required standards and safety guidelines.

  • Familiarize yourself with local building codes and obtain any necessary permits before starting the construction process.

  • Identify any potential obstructions or utilities that may affect the placement or construction of the retaining wall.

  • Follow proper excavation and backfilling techniques to ensure a solid foundation and proper drainage.

  • Regularly inspect the wall for signs of damage or failure and address any issues quickly.

Conclusion

Engineered retaining walls are crucial for stability and safety in construction projects. The engineering process involves thorough site analysis and material selection. Common challenges like drainage issues can be addressed with professional advice and installation tips. It's important to differentiate between engineered and non-engineered solutions to guarantee a safe wall. With a focus on design principles and proper installation, engineered retaining walls provide a reliable solution for many construction needs.


For more information about engineered retaining walls and retaining wall designs, call Retaining Wall & Paving Solutions at: 314.518.4523.

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