Gabion Wall Standard Design

Author: wenzhang1

May. 06, 2024

Gabion Wall Standard Design

Introduction to Gabion Design

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Fine Mesh Metals Ltd are not structural engineers. The designs presented here are suggestions based on industry-standard designs. While gabion wall designs are robust and commonly form the basis for work by structural engineers, specific situations may require more tailored advice. If your project involves notable infrastructure or is on challenging ground like very soft clay, consulting an experienced engineer is essential. This ensures compliance with Health and Safety standards. It’s imperative for clients to hire qualified professionals familiar with the construction's risks.

A Consulting Engineer Will Need:

  • A topographic survey to ascertain wall height and slope surcharge impact.
  • Proposed wall location.
  • Ground investigation for retaining and foundation soils, along with geotechnical parameters.

Consulting engineers may incur additional costs, but we can recommend professionals if needed.

The guidelines provided should not replace detailed advice from a consulting engineer. Fine Mesh Metals Ltd does not accept liability for actions taken based on these suggestions.

Fine Mesh Metals Ltd can’t compensate for any losses stemming from adherence to these standard designs.

Gabion Standard Designs

Gabion basket designs, particularly in welded mesh types, are robust and reliable. At Fine Mesh Metals Ltd, we’ve never witnessed a failure with properly installed and filled gabion walls.

Impact of Load Behind the Wall

A load like a car park typically adds a surcharge of 2.5kN/m2, generally manageable by standard designs. Access roads for heavy goods vehicles increase the surcharge to 10kN/m2, necessitating consultation with an expert, especially if a building is within 3 meters of the wall.

Footings and Foundations

(Please see detailed explanations below)

Construction standards recommend a 500mm trench to accommodate future excavations, get below the frost layer, and prevent baskets from slipping. Topsoil may contain organic matter that rots or compresses. Although many short walls start at ground level, it's important to evaluate ground conditions on-site.

Soft clay is the worst material for gabion walls as it can sink under the weight. Compacted hardcore (type 1) around 100-200mm should serve as a footing. The initial trench depth should match these guidelines.

Baskets should be leaned back at 6 degrees. According to BS8002:2015(7.3), a gabion wall should be angled to increase resistance to overturning and sliding.

Gabion wall faces can be flush or stepped, depending on wall height. Baskets can also be cut to custom dimensions.

For walls up to 3 meters, the standard thickness is 3mm. Thicker diameters like 4mm or 5mm are used for more demanding applications. Additional face thickness can be added to minimize bulging risks.

Health and Safety Considerations

All construction must comply with Health and Safety regulations, specifically CDM Regs 2015. Given construction's risks, proper precautions are necessary to prevent injuries or fatalities. For instance, unsupported excavations can be hazardous.

Temporary propping may be impractical, so unsupported excavation is common, typically at a 45-degree angle. Such practices are included in standard design calculations.

Example Gabion Wall Configurations

1m High Wall

A 1-meter high wall is straightforward and can use 1m x 1m or 2m x 1m x 1m baskets. Smaller baskets reduce transport costs. It is standard to use 3mm wire thickness for these walls.

2m High Wall

Gabion baskets are mass retaining systems. For a 2-meter wall, the base row should be 1.5 meters deep, with standard 3mm wire thickness.

3m High Wall

This design uses 2-meter-deep baskets at the base, 1.5 meters in the middle, and 1 meter at the top. Applying thicker wire, such as 4mm for the bottom row, may be advisable.

Curved Gabion Walls

Curved walls come in inside and outside bends. Inside bends use standard baskets, while outside bends require tapering and precise on-site adjustments.

River Erosion Protection

Gabion mattresses (short baskets) are typically used in river settings to prevent the foundation erosion. For installations near water, incorporating a non-woven geotextile filter membrane like Terram T1000 is advised to prevent soil strain and voids.

Flood Protection

Gabion baskets are permeable and can be lined with geotextiles to prevent water passage. This is effective for specific locations, but all joints must be sealed carefully.

Note on 500mm Trench

According to BS8002 standards, an additional 500mm trench depth accounts for unexpected and planned excavations. The trench provides stability, frost protection, and avoids organic soil disruption.

BS8002:1994 has been replaced by Eurocode 7 and BS8002:2015, which offer updated guidelines.

Gabion walls must comply with Eurocode 7's stipulations about stable balance and soil behavior, highlighting considerations like frost and organic material impact.

Proper foundational setup includes using well-graded materials or concrete for alignment and avoiding soft or organic-rich soils.

Example Images of Good Practices

6-meter High Flush Faced Gabion Wall

10-meter High Flush Faced Gabion Wall

Curved Stepped Gabion Wall

Proper Gabion Stone Placement

For more detailed insights, visit our page on woven gabions. For additional information, refer to 5 Reasons ODM Star Pickets Outperform the Competition.

Stone Placement in Gabion Walls

Narrow Gabion Facing to Sheet Piling

Frequently Asked Questions

What Are Gabions?

Gabions are mesh containers made of galfan-coated steel, filled with rock, stone, or recycled materials. Constructed from various-sized panels, these containers are connected with spiral or C-Rings to form robust, flexible structures ideal for retaining walls, erosion control, and many other applications.

Cost-Effectiveness

Gabions are a cost-effective solution for most scenarios. Woven gabions, often used in large-scale projects, are less expensive but offer a shorter lifespan. Weld mesh gabions, designed with 4mm welded panels, are preferred for their form and functionality in landscape and architectural applications.

Type of Rocks to Use

The recommended rock size for gabions is 75mm-150mm, with basalt being a durable choice for structural projects. Local quarries can provide advice on suitable rocks based on color, texture, and availability.

Durability

Woven baskets, made from 2.7mm wire, are less durable than weld mesh baskets made from 4mm wire. Gabions with galfan coating can last anywhere from 50-100 years, while galvanized ones may last only 5-10 years. Quality varies by manufacturer and origin, so high standards are essential.

Types of Coating

Galvanized Coating

Galvanized coatings are common but may not meet industry standards for gabion structures. Substandard materials often result in early corrosion and structural failure.

Galfan Coating

Galfan coatings offer better performance and durability, especially when coupled with high tensile strength mesh. Century Gabions, for instance, are designed to exceed Australian standards and offer superior longevity.

Do Gabions Need Foundations?

Gabions are usually laid on compact road bases for support. Retaining walls over 2-3 meters should be angled back for stability. Foundations may also include internal steel posts for added sturdiness.

Size and Configuration

For retaining walls, a 2:1 height-to-depth ratio is typical. Smaller projects may vary, and professional consultation is recommended for larger or more complex designs.

Planning Permission

Check local council regulations. In many regions, walls up to 1 meter height don’t require permits, but taller structures might.

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