Earthbag retaining walls

Introduction to earthbag retaining walls

Earthbag retaining walls use synthetic fibre bags filled with sand and compost to create a retaining wall. The design is either gravity or geogrid-reinforced. Earthbags are ideal for permanent vegetative solutions.

The earthbags are manufactured using a nonwoven geotextile produced by needle-punching together 100% synthetic staple fibres in a random network, forming a high-strength, dimensionally stable fabric. The Synthetic fibres are specially formulated to resist ultraviolet light deterioration and are inert to commonly encountered soil chemicals. The life span of the bags are 120 year when vegetated and 40 years when unvegetated.

Approximate earthbag sizes: length 660mm, width 380mm, height 140mm, volume 0.3 m3 and weight 38kg filled. Twelve bags are required per m2 for a standard stretcher bond and sixteen bags for a tie-back design.

Earthbag applications

Earthbags can be used for many applications, including:

• Vegetated gravity retaining walls up to 1.5m high
• Vegetated geogrid reinforced stone retaining have no height restrictions
• Timber criblock repairs
• River bank restoration and erosion protection
• Stormwater channels
• Culvert end walls

Earthbag design

For walls up to 1.5m high, a simple gravity design is the most economical. Wall heights over 1.5m require a stone geogrid reinforced backing.

Gravity design

The foundation is an MOT type 1 stone-filled trench; then the earthbags are laid to the structural design. The bags can be filled on-site or off-site, depending on the site constraints. The bags are filled with 60/80% sand and 40/20% compost. No height restrictions.

The geometry and mass of the wall prevent the wall from slipping and overturning.

Reinforced soil design

The foundation is similar to the gravity design.

Geogrid reinforced stone, with a width of 80% of the wall height, acts as the structural retaining structure, with a face of earthbags. The earthbags are then seeded to create a green, vegetated wall surface.

Earthbag retaining wall design guide

The design guide will give you an idea of the height of walls retaining rock can achieve. You can use it for budget purposes, but make sure you have your retaining wall designed by a structural engineer as there are many variables that need to be considered.

Height (mm)	1000	1500	2000	2500	3000	4000	5000
Number of bag Courses	9	13	17	20	24	31	38
Bag Height (mm)	140	140	140	140	140	140	140
Base Width (mm)	1000	1000	1600	2000	2400	3200	4000
Base Depth (mm)	150	150	150	150	150	150	150
Geogrid Layers	N/A	N/A	5	6	8	10	12
Geogrid tail length (mm)	N/A	N/A	1600	2000	2400	3200	4000
Earthwall fill	N/A	N/A	Type 1	Type 1	Type 1	Type 1	Type 1
Surcharge	5kn/m²	5kn/m²	5kn/m²	5kn/m²	5kn/m²	5kn/m²	5kn/m²
Factor Of Safety	M=1.5	M=1.5	M=1.5	M=1.5	M=1.5	M=1.5	M=1.5
Sketch

The design table above presents indicative designs based upon a base material with allowable bearing pressure of >200kPa.

The retained material is assumed to be well graded, granular backfill with the back of wall drainage or weep holes to relieve hydrostatic pressure. Fill used for the reinforced geogrid structure to be type 1 stone 40/50mm graded stone.

All indicative information presented in this table is based upon assumed loading and ground conditions. This table is for guidance purposes only and may be subject to change following a detailed, site-specific design developed by an approved structural engineer.

When we design your wall, we will consider the ground conditions, the retained material, the load cases and design the wall using the most cost-effective solution.

The purpose of the design guide is to allow us/you to develop a budget.

Prices

The fastest way to get a price for your project is complete the form below. Let us know if you just want bag prices or our complete service of design and supply.