Nehemiah
Wall is a type of reinforced soil system based on Anchored Earth®
concept whereby the mode of stress transfer from the backfill to
the reinforcement is by passive resistance in addition to friction.This
System is reinforced by galvanised steel bars and anchored by precast
concrete blocks. The facing is vertical consisting of modular hexagonal
shaped concrete panels interlocked together.
The schematic representation of
Nehemiah wall is as shown below. The system consists of three major
components namely the facing, the reinforcing bars and anchor blocks.
Facing
Panel
The facing panels are hexagonal shaped and are made of precast
concrete (grade 30). They are interlock with dowels bars with
tolerance for horizontal movements. The horizontal joints between
the panels are inserted with compressible material to allow
for vertical movement. As such the facing is flexible and can
tolerate large differential settlement.
Reinforcing
Bars
The reinforcing bars are made of carbon steel rods in compliance
with BS 8006:1994 Code of practice for Strengthened/reinforced
soils and other fills.The bars are hot-dipped galvanised to
prevent corrosion. The advantage of using round bars instead
of strips is that it is more durable against corrosion in view
of the reduced surface area exposed. The bars are connected
to the facing panels by nuts with the threaded end coated with
epoxy.
Anchor
Blocks
The anchor blocks are discrete precast concrete blocks which
act as deadmen. A hole is preformed in the centre of the block
to enable the reinforcing bar to pass through thereby connected with
nut and washer.The advantage of using anchor blocks is that
it enhance the pull out resistance of the reinforcing bar.
As a result, the use of cohesive frictional material as backfill
is possible since the system does not rely so much on friction
for the stress transfer.
Schematic representation of Nehemiah wall
Systems
Typical Section of Nehemiah Wall
Back-to-back Wall for Highway
Nehemiah tiered Wall
The system is ideal for
Urban highway interchanges
Mountainous Highways
Railway embankments
Bridge abutments
Housing retaining walls
Marine walls
Rivers walls
Secondary containment dykes
Military walls
Advantages Nehemiah wall is the chosen technology because of the following
advantages :
Cost
Effectiveness
Nehemiah wall is more cost effective compared to the conventional
type of earth retaining structures. The cost savings can be
as much as 30%, depending on the height of the wall and the subsoil
condition.
Rapid
and easy Installation
The time taken for construction of Nehemiah Wall is much faster
as casting of panels can be independently done while site preparation
and foundation work is going on. The erection of the wall can
go on simultaneously with the back filling, thus saving valuable
time. Only a few skilled and unskilled labors are needed. The
construction procedure is highly mechanized; hence the time
required for erection is short.
Aesthectically
pleasing
The precast facing is aesthetically pleasing in apprearance.It
easily allows for various geometrical shapes, logos and other
architectural finishes.
Flexibility
Nehemiah Wall is a flexible structure and may withstand substantial
total and differential settlement. In view of its flexibility,
the need of piled foundation on marginal ground can sometimes
be dispensed with thereby achieving further cost savings.
Durable
The design of Nehemiah Wall is carried out in full compliance
to BS 8006:1995 " Strengthened/ reinforced soils and other
fills." and the design life span can be up to 120years.
Services Provided
Professional services provided free of charge are as follows :
