Netlon Applications

Netlon in roads

The loss of sub-base material into a soft sub-grade affects the load bearing capacity of the road construction, and in the absence of timely and costly maintenance, deterioration increases until ultimate failure occurs.
Nelton Geogrid laid at the sub-base/sub-grade interface prevents the penetration of sub-base material into the sub-grade, and increases the bearing capacity of the sub-grade. (Fig. 1)
Netlon Geogrid performs similar function in providing a stable foundation with many applications and advantages :
i. It prevents loss of sub-base material into the sub-grade.
ii. It distributes load uniformly over a wide area by virtue of its stiffness, thereby reduces differential settlement.
iii. It adds to the shear strength of the soil by virtue of its high tensile strength fully mobilized by the high friction value of the net profile.
iv. Its net structure allows more rapid dissipitation of pore water pressure.
Geogrid-soil Interaction :
Netlon Geogrid are fundamentally different from traditional soil reinforceing inclusions in that the fill on one side of the grid can key with the soil on the other side, through the grid apertures. The Mechanical Interlock allows a high degree of compaction to be achieved producing a high density shear resistance layer effectively distributing traffic loads.
Netlon Geogrids strengthen soils in two ways :
a- Local shear stress in the soil are transferred into the grid as it extends, thus reducing the stresses within the soil.
b- The grids distributes stresses away from areas of high stress.
These are the basic principles of soil stabilization using geogrid

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Pumping Phenomenon

The dynamic loading of aggregate soil systems, such as in road construction, leads to a much more rapid breakdown of the system than would be caused by sustained static loads. It leads to the dispersion of the granular fill at the base of the layer. This in turn causes large permanent deformations.
When a layer of Netlon geogrid is placed within the fill, the dispersion is resisted by the stone particles which lock into the grid apertures. In addition to large deformations generated directly as a result of dynamic loading, the breakdown of the road structure is further accelerated by the phenomenon known as pumping.
As the road is subjected to dynamic deformation, granular particles in the lowest layers of the sub-base are oscilated laterally causing a pumping action. If these particles are in intimate contact with fine cohesive soil and in the presence of water, the fine soil particles are pumped upwards to fill the voids in the sub-base thus reducing its strength. The progressive movement of the subsoil into the voids is shown in Fig.
Netlon georids interlock with sub-base particles restraining lateral movement of the stones in the lowest layer of the subbase, thus, resisting this pumping action

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Road Construction Details

Installation
1- Sub-grade is excavated to its desired level.
2- The Netlon grids are rolled out over the sub-grade usually in the direction of travel.
3- Adjacent rolls can be overlapped, sewn or pinned together using U shaped pins.
4- Granular aggregate is back tipped onto the grids, and using light equipment is spread to a depth slightly greater than desired.
5- Compact to desired thickness.
6- Minimum overlap with pin or sewn is 0.1 meter.
7- Minimum overlap without pin or sewn is 0.3 meter.

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Pipe laying

When used in pipe laying, the use of Netlon CE 131 as a restraint layer below the aggregates function as follows :
i) The aggregates interlock with Netlon CE 131 geogrid forming a highly compact layer for effective load distribution. The net effect would therefore be a uniform settlement due to an even load distribution.
ii) The open mesh structure of the geogrid allows unimpeded flow of water and hence rapid dissipation of pore water pressure.

Nets in parking area

Land Reclaimation

Netlon has played a leading part in reclaiming land for shore installations, in providing a foundation for the construction of rubble core sea walls, for protective armouring, and in subbase ground restraint. Fig shows a typical example of the sequence of construction in forshore reclamation for an industrial project. Netlon geogrid 'distributes' load uniformly over a greater area by virtue of the tension forces mobilized in the high friction net, and prevents the loss of fill material into the sub-grade.

Railway Construction

With the increased dynamic forces resulting from the trend towards higher speeds, there is a need to improve and maintain track to a higher standard. To achieve the design objectives of track stability under high vertical and lateral forces, passenger comfort and ease of maintenance, consideration must be given not only to the geometry and composition of the track and its sub-structure, but also to the earth works below, which must ultimately bear the applied load.
Under repetitive tie loading condition, railway ballast undergoes non-reversible vertical deformation, settlement due to puncture of ballast, abrasion, densification, contamination, degradation and lateral spreading under the ties. Geogrids have demonstrated their ability world wide to cost effectively reinforce and interlock ballast in numerous applications. It acts in the interface as a separator anchor sheet and reduces permanent deformation substantially.
Use of geogrid as compared to other alternatives, does not require any traffic block and therefore are extremely advantageous in safe maintenance of running lines.

Sand as filter

Sand as natural filter are chosen under geogrids to provide for permeability and prevention of piping as per following criteria :
- D15 filter < ( 5 D 85 soil) against piping
- D15 filter < ( 5 D 15 soil) against piping
- D15 filter < ( 25 D 50 soil) against piping
The sand being natural material, it provides a clog free, non-compressible drainage layer providing enough planner permeability.

For Slopes (Replace Stone work)

Multi layer application

Factory foundations

Netlon provides an effective and economical method of improving load distribution over large heavily loaded areas of made up ground. Foundation design of industrial structures can be greatly simplified by adoption of ground restraint techniques, to improve the bearing capacity of the soil, thus obviating the need for expensive foundation systems.
Netlon CE121 or CE131 are normally used for this application either in single layer at the aggregate/sub-grade interface or in multiple layers where the thickness of the aggregates exceed 500 mm.

Multi-layer foundations and pavement structures
Multi layer horizontal masses are used over particularly difficult variable ground conditions and for the distribution of high loads. As shown, this type of structure consists of alternate layers of fill and Netlon geogrids. Simple stability analysis indicates that the major reinforcing effect, achieved by the addition of Netlon geogrids, is due to the high pull out resistance of the grid developed at low normal stress.
The inclusion of several layers within the structure binds the whole mass together and increases the ability of the structure to redistribute internal stresses. Again, the unique interlocking ability of the grid is an effective stress transfer mechanism by which the tensile strength of the grid is mobilized. The additional layers allow the structure to perform as a composite beam, by constraining internal movement and stiffening the mass over its complete depth.
A multi-layer horizontal mass has a greater resistance to differential settlement due to variable ground conditions and the imposed loads. .

Errosion and Cliff face Protection

Access over waterlogged Terrain

Access to areas where breaches have occurred in river banks can prove difficult in the presence of large alluvial plains and mud flats, particularly when these areas have to be traversed for transporting materials and carrying out remedial works.
Netlon geogrid laid directly over the silt performs two functions. It provides a stable platform enabling construction work to be undertaken in safety, and also serve as a foundation for more permanent access ways, and for remedial work to river banks.
Netlon geogrid is particularly suited for use in swamps, peat and paddy field areas where it provides a sound platform for placement of fill material. The open structure of the grid allows unimpeded flow of water, a characteristic unique to Netlon geogrids. This is especially important when used in swamps where the geogrid and fill material sinks together uniformly enabling construction work to progress unhindered.

Retaining walls and bridges Abutment

Gabions Applications

Maritime Applications

Water way Applications

Construction over weak soil and Roads

Retaining wall (in Rail ways)

Fencing

Other Applications