"Important NOTE" Information Provided On This Website Is
Intended For "GENERAL INFORMATION ONLY" And Must Be Only Be
Used Only As A "GUIDE" It Must Not Be Used For Decision Making, Or
Be Used For Any Building Purposes Or Legal Proceedings. Refer To Our Policies On This Website.
RETAINING WALL DESIGN
The purpose of a retaining wall is to stabilize earth which will otherwise cave in or slide
towards a more natural slope.
A badly designed retaining wall is a disaster waiting to happen.
It is imperative that a retaining wall, must not only be designed properly, it must also be
constructed
properly.
A retaining wall should be considered primarily as a load bearing structure & aesthetics is only
secondary.
Proper drainage must be provided to reduce the hydrostatic pressure of ground water behind the
wall.
The type of retaining wall design depends on lateral earth pressure, soil and drainage
conditions.
There are many types of retaining walls such as:
* Gravity
* Cantilever
* Sheet piling
* Anchored
GRAVITY:
A gravity type retaining wall depends on its weight to hold it in place.
It may be provided with a batter setback to enable it to have greater stability against the lateral soil
pressure.
Gravity retaining walls are built from concrete, stones or any suitable heavy materials. The
choice of
materials to a large extent depends on site conditions.
For short landscaping walls, where the lateral soil pressure is not very high, it can be built
from motarless stone or masonry units.
Since dry stacked retaining walls are flexible to some extent, even in frost prone areas, they do not need a
rigid base.
The use of large quantities of stone or concrete for tall gravity retaining walls has been
replaced with composite gravity retaining walls.
These walls are made of synthetic materials, pre-cast facing, gibbons, crib walls, soil nailed walls
etc.
CANTILEVER:
A cantilever type gravity wall is usually in the shape of an 'L' or inverted 'T'. It is made
using reinforced concrete.
A cantilever retaining wall works by converting the lateral soil pressure pushing against the
wall, into vertical
pressure which acts on the ground below.
At times a cantilever retaining wall will be provided with a buttress in front and a counter
fort on the rear
side for better stability against high loads.
A cantilever wall requires proper concrete footing which has to be located below frost
depth.
The advantage of a cantilever wall is that, for the same loads, it uses much less material than a gravity retaining
wall.
The disadvantage is that a proper foundation has to be provided and hence excavation of the soil
is
necessary.
SHEET PILING:
These types of retaining walls are used where the space is limited and the soil is soft. The
sheet pile walls
are usually built out of steel, vinyl or wood planks.
As a thumb rule, the material is driven into the ground up to 2/3rd of its depth.
However, this depends on the site conditions and may vary somewhat.
To hold taller sheet pile retaining walls in place, a tie-back anchor or 'dead man', has to be
placed in the
soil behind the wall. It is tied to the wall by using a cable or rod.
Care should be taken to place the tie back anchor behind the potential failure plane of the
soil. This will enhance the stability of the sheet piling.
ANCHORED:
An anchored retaining wall can be any of the other types of retaining wall, but the difference
lies in the fact additional strength is imparted by using cables or stays, which are anchored in the soil or
rock behind the
wall.
The anchor end is driven into the soil or rock by boring and it is expanded using mechanical
means or by
the injection of pressurized concrete.
This gives a bulb shape to the anchor end and helps it to be held in place.
The advantage of this type of retaining wall is that it can withstand high loads, but at the
same time the wall can be slender.
The Other Alternative Retaining Techniques Available
Are:
* Soil nailing - in this method, retaining walls are reinforced using reinforcing
bars.
* Soil-strengthened - in this type the lateral earth pressure itself is reduced by various
methods.
It is usually used in combination with other types of retaining walls.
* Gabion meshes - here soil is strengthened by using wire mesh boxes, filled with stones or any
other material.
It helps in reducing internal forces and erosive forces. Retaining walls play a major part in construction.
A poorly designed and constructed retaining wall will collapse sooner or later and it can endanger other buildings
or structures in the vicinity.
In many places building a retaining wall, greater than a certain height, requires
permission/certification.
Generally a factor of safety of 1.5 is incorporated into the design of the retaining wall.
A properly designed and constructed retaining wall will have a long service life.
|
Videos Are Under Construction They Will Be Uploaded
Soon |
|
Videos Are Under Construction They Will Be Uploaded
Soon |
"Important NOTE" Information Provided On This Website Is Intended For
"GENERAL INFORMATION ONLY" And Must Be Only Be
Used Only As A "GUIDE" It Must Not Be Used For Decision Making, Or
Be Used For Any Building Purposes Or Legal Proceedings. Refer To Our Policies On This Website.
|