Products & Services
Professional Services
Nehemiah Reinforced Soil Pty Ltd is staffed with experienced and competent professional engineers and project coordinators. The following services can be provided free of charge :
- Engineering services to assist in design computations, analysis and preparation of drawings from client provided design concepts to final construction drawings. The design is carried out in compliance with either AS4678 - Earth Retaining Structures, RTA R57 - Design of Reinforced Soil Walls and / or BS8006:1995 Strengthened/ reinforced soils and other fills.
- Assistance in the preparation of material and construction specifications.
- Detailed cost estimates.
- Technical advice and assitance during construction
Products
Nehemiah Wall is a type of reinforced soil system based on an Anchored Earth® concept where by the mode of stress transfer from the backfill to the reinforcement is by both friction and passive resistance.The backfill soil is reinforced by galvanised steel bars which are anchored into the soil using precast concrete blocks. A vertical facing consists of modular hexagonal shaped concrete panels interlocked together. A wide range of architectural finishes can be applied to the facing panels, according to the clients wishes.
A schematic representation of Nehemiah Wall is as shown below. The system consists of three major components namely the facing, reinforcing bars and anchor blocks.
Facing Panel
The facing panels are hexagonal shaped and are made of precast concrete (minimum grade 40). The panels can be interlocked with dowels bars during installation and have a built in tolerance for minor horizontal movements. The horizontal joints between the panels include a compressible material to allow for vertical movement. As such the facing is flexible and can tolerate expected differential settlement.
Reinforcing Bars
The reinforcing bars are standard 500 MPa deformed bar in compliance with relevant Australian Standards. Alternatively coarse threaded high strength bar can be used. In most permanent applications the bars are hot-dipped galvanised to prevent corrosion. The advantage of using round bars rather than strips is that the bars are more durable from corrosion in view of the reduced surface area exposed. The bars are connected to the facing panels by nuts with the threaded end galvanised or coated with epoxy.
Anchor Blocks
The anchor blocks are discrete precast concrete blocks which act as a deadman on the end of each reinforcing bar. A hole is preformed in the centre of the block to enable the reinforcing bar to pass through and be secured with a nut and washer.The advantage of using anchor blocks is that they 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 solely on friction for the stress transfer.
The system is ideal for
- Urban highway interchanges and overpasses
- Railway embankments
- Bridge abutments
- Housing retaining walls
- Marine walls
- Rivers walls
- Secondary containment dykes
Advantages
Nehemiah Wall is the chosen technology because of the following advantages :
Cost Effectiveness
Nehemiah wall is more cost effective compared to conventional types of earth retaining structures. The cost savings can be as much as 30% depending on the height of the wall and the prevailing subsoil condition.
Rapid and Easy Installation
The time taken for construction of a Nehemiah Wall is much faster than for conventional earth retaining structures as casting of panels can be independently done while site preparation and foundation work is going on. The erection of the wall can proceed simultaneously with the back filling, thus saving valuable time. Only a few skilled and semi-skilled laborers are needed. The construction procedure is highly mechanized and hence the time required for erection is short.
Aesthectically pleasing
The precast facing is aesthetically pleasing in appearance. It easily allows for various geometrical shapes, logos, colourings and other architectural finishes.
Flexibility
Nehemiah Wall is a flexible structure and can withstand substantial total and differential settlement. In view of its flexibility, the need for piled foundations on marginal ground can sometimes be avoided, thereby achieving further cost savings.
Durable
The design of a Nehemiah Wall is carried out in full compliance to AS4678 and RTA R57. The design life span can be up to 120 years.
Services Provided
Professional services provided free of charge are as follows :
- Material and construction specification
- Construction advice and assistance
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