Different Types Of Retaining Walls are described here. Gravity Wall, Gabion Wall, Cantilever Wall, Counter-fort Wall, Crib Wall, Piled wall, Sheet Piled wall, Soil Nailed Wall, Reinforced Earth Wall or Mechanically Stabilized Earth Wall, etc.

Types of Retaining walls, Materials, And Applications:

What is a Retaining Wall

Retaining wall can be defined as a wall that retains the earth or soil behind it and resists lateral soil pressure as well as hydraulic pressure. Weep holes provide in R.C.C. retaining walls to release excessive hydraulic pore water pressure.

Types of Retaining Walls:

Different Types Of Retaining Walls are described here.

Gravity Wall,
Gabion Wall
Cantilever Wall,
Counter-fort Wall
Crib Wall
Piled wall,
Sheet Piled wall,
Soil Nailed Wall,
Reinforced Earth Wall or Mechanically Stabilized Earth Wall.

The above Retaining Walls are briefly described below-

1. Gravity Wall:

Picture-1: Stone Masonry Gravity Wall

Meaning of gravity wall is a retaining wall which is opposing the upcoming force by its own weight" Gravity walls are the earliest retaining structures. They are constructed by the combination of solid concrete and rock rubble mortared together, the lateral forces from the backfill (Earth filler material) are resisted by the weight of wall itself, due to their massive nature. They are not usually reinforced with steel. Gravity walls are economical for heights up to 3m as they are only used for short slopes.

The main forces acting on gravity walls are the vertical forces from weight of the wall, lateral earth pressure, and seismic loads.

2. Gabion Wall:

Gabion wall is a retaining wall made of wire crates filled with stones or earth materials. They are usually battered, stepped, and sometimes vertically stacked. Gabion walls uses to control land sliding on road embankments, to resit erosion and scouring on the rivers banks during flood or high steep river streams and prevent the water logging from further damaging.

Some advantages of gabion walls are:

Ease of handling and transportation.
Speed of construction,
Flexibility (Gabions tolerate movement),
Permeability to water (Good drainage)
Gabions offer an easy method to decrease water velocity and protect side slope slopes from erosion,
Angular rock is the best gabion filler material to make an interlocking block.

Gabion walls are executed mainly for the purpose of soil stabilization behind the wall, but it can also be executed as a cover wall.

3. Cantilever wall:

Picture-2: Cantilever Wall.

Cantilever walls have two arms and consist of a horizontal footing and a vertical stem wall. In general, the maximum excavation for a cantilever wall can reach up to 6m (18ft). moreover, deeper cantilever walls have been constructed in the past, but these require more expensive wall systems. It offers an unobstructed open excavation and does not require the installation of tiebacks. It is generally not recommended to use cantilever walls next to adjacent buildings. It should be L-type or inverted T-type in shape.

The cantilever wall rests on a slab foundation and the weight of the soil mass above the heel helps to keep the wall stable. Cantilever walls are economical for heights up to 10m. the shear key is provided in retaining walls to reduce the sliding action or to make the structure stable against the lateral loads. It depends on the nature of loading.

4. Counter-fort wall:

Picture-3: Counter-Fort retaining Wall

Counter-fort retaining wall is a cantilever wall with a counter-fort, or buttresses, attached to the inside face of the wall to further resist lateral thrust. Some common materials used for retaining walls are treated lumber (Timber), concrete block systems, poured concrete, stone, and brick.

5. Crib walls:

Crib walls are made up of interlocking individual boxes which are made from timber or pre-cast concrete. The boxes are then filled with crushed stone or other coarse granular materials to create a free drainage structure. As they are permeable and allow to drain freely where necessary. The wall can be made with one or multiple rows of cribs at the base, depending on the height of the retaining structure to be formed. In order easy to construct, the backfill is placed and compacted keeping it to the same level reached by the wall. There are two basic types of crib walls-

Timber and reinforced pre-cast concrete.

Crib walls are commonly used for residential purposes such as stabilizing building platforms and driveway access. They are very adaptable and can be straight and curved or angled. Crib walls are able to sustain a differential settlement.

6. Piled wall:

Picture-4: Piled Retaining Wall

Piles are the circular structural elements, which are executed in the ground and the purpose of piles execution is to transfer the loads, which will act on piles such as horizontal and vertical loads into deeper and its much deeper and better layers of the soil of foundation. Piles are executed to each other, a wall name pilot is formed and this pilot wall is used as temporary and permanent retaining structure in soil mass.

There are many types of pile walls are use as per condition on site: -

*According to types of resistance the pile wall divided as cantilever or a supported structure.

*According to pile layout the pile wall divided into a secant/ tangent or contiguous pile wall.

So we can classify pile wall into the following categories such as follows: -

• Cantilever pile wall

• Supported pile wall

• Contiguous pile wall

• Secant or tangent pile wall

• Cantilever pile wall: It’s represents a retaining structure that performs without any additional support. This pile wall is executed by digging under excavation level or slide surface and stabilizes the soil mass due to the resistance of soil mass of the backfill material.

• Supported pile wall: It’s represents a retaining structure that performs with additional support. When is not possible to ensure the stability of structure for design loads.

• Contiguous pile walls: it executes with spacing between piles and those pile walls mainly applied in fine grained materials and this type of material reduce the material’s collapse possibilities between the piles if it required. Also the shotcrete layer can be used for provide the stability to the materials.

• Secant or tangent pile wall: it is formed by executing intersecting pile of concrete. One face includes primary pile’s executing which are executed without reinforcement. After achieving the appropriate strength and installation of concrete the secondary pile’s execution is drilling through foundation soil and partly through the primary pile. Both piles are overlap about 8 to 10 cm. After completion of drilling the piles are reinforced with steel bars/ profile and concrete is installed. Tangent pile walls consist of piles that touch but do not overlap. And all tangential piles must be reinforced.

7. Sheet piled wall:

Sheet piled wall: sheet piled walls are one retaining walls constructed to retain earth, water and other filling materials. These walls are thinner as compared to masonry walls. These walls are generally use for

• water front structure, building wharfs, quays and piers.

• Building diversion dams

• River bank protection etc.

There are many types of sheets piles such as follows

• Timber sheet piles

• Reinforced concrete sheet piles

• Steel sheet piles etc.

8. Soil nailed wall:

This technique uses to bring stability of soil in such kind of land sliding areas. Soil nail can play a vital role to prevent land slide by inserting steel reinforcing bars into the soil and anchoring them toward the soil strata. Its having a nail which being hammered to the soil and this is the reason it called soil nailed, where steel bars playing a role of nail.

Soil nail walls uses are as follows: -

• Roadway cuts

• Road widening under existing bridge abutments

• Tunnel portals

• Repair and reconstruction of existing retaining structures

• Hybrid soil nail systems

• Shored Mechanically Stabilized Earth (SMSE) walls

9. Reinforced Earth/Soil wall

or Mechanically Stabilizes Earth/Soil Wall:

i. RE Panel Wall.
ii. Segmental Blocks Reinforced Earthen Wall.

i. RE Panel Wall:

Picture-5: RE Panel Wall

As we know that Reinforced Earth Wall (RE wall) is used for sustaining soil laterally so that it can be retained at different levels on both sides of the carriageway. It is a combination of backfill (Non-cohesive material) and linear reinforcement in the form of strips, grids such as geo-strips and geo-grid. These are capable of bear large tensile stresses.

Precast RE-Wall panels are used as a skin and it is self-stabilized structure.

ii. Segmental Blocks Reinforced Earthen Wall:

Picture-6: Segmental block MSE Retaining Wall

This type of Mechanically Stabilized Earth (MSE) retaining wall is a composite structure consisting of alternating layers of compacted backfill and soil reinforcement elements, fixed to a wall facing. In other words, the retaining structure is made up of three main components: granular soil (backfill), metallic or geo-synthetic supports and facing units.

The wall facing is relatively thin and the facing elements are modular precast concrete panels or wire mesh.

Each facing type offers different advantages when considering criteria such as durability and appearance. Soil reinforcements are generally used steel and geosynthetic strips. It offers higher resistance to seismic ground movement and other dynamic forces and it can be built at extreme level of height. It reduces the overall span length of the structure as well as reduce the abutment costs.