SOIL REINFORCEMENT

Soils have relatively low tensile strength so that they are not able to transfer all of forces arising in a structure when it is loaded. The tensile forces created can be transferred using geosynthetics materials - geogrids, geotextiles or geocomposites. The geosynthetics products used as a reinforcing element, hence the term reinforced soil.

To ensure satisfactory performance of the reinforcement, a low elongation under stress and good design with respect to a type of soil being reinforced is essential. Geogrids are more suitable for grainy and non-cohesive materials (sand and gravel) while woven geotextiles or reinforcing geocomposites are better for cohesive, fine-grained soils (clay, loess).

Benefits of use of geosynthetics materials for reinforcement:

improvement the mechanical properties of soils
otherwise unsuitable types of soil can be used
expensive structural designs are avoided
undesirable mixing of soils and demands for earth moving are minimised
extension of the existing road or railway embankments to increase their capacities can be easily achieved
minimum land take required
natural noise reduction barriers/ walls are easily constructed
construction time is shorted (earthworks also in winter)
embankment safety and stability is increased
natural appearance of landscape is maintained
costs for construction is optimised

IMPROVEMENT OF LOAD-BEARING CAPACITY

Use of geosynthetics materials represents one of effective methods of improvement of load-bearing capacity, above all wherever mechanical properties of local soil cannot provide the required level of stability and load bearing capacity.

When constructing horizontal structures, geosynthetics materials are utilized to balance uneven settling, to absorb loading forces and frequently also to reduce thickness of expensive coarse-grained material. Geosynthetics materials (above all geogrids) will form a base composite by grainy material interlocking which is effective even on the substrates formed by peat or soft silt.

Main advantages of use of geosynthetics materials for transportation constructions:

Founding on soil with low load bearing capacity
Reinforcement of embankment above the piles
Reduction of deformations of embankment bodies
Separation of coarse-grained material and subsoil layers
Utilization of inferior soils
Achievement of the required high traffic speeds on the roads and railways

SUPPORTING STRUCTURES

If we construct supporting structures or steep embankments of soils, the shear strength of which would be exceeded under normal circumstances, it is possible to achieve the required safety using horizontal reinforcement of the embankment layers with geosynthetics materials (geogrid or geotextile).

The face of retaining wall can be made of GABIONS or CONCRETE ELEMENTS (prefabricated blocks, panels, segments) where geosynthetics materials are used as horizontal reinforcement. It can be also made as a SOFT FACE (by so called wrapped-around method). The face of the structure is formed by geosynthetics material itself in this case, dropping fine-grained filling material out through the apertures of the geogrid can be prevented by adding nonwoven or erosion control geosynthetics in the face.

Only in the cases when the angle of internal friction of soil exceeds the slope inclination, it is not necessary to make reinforced face. However, the slope surface should be protected against effects of erosion using e.g. erosion control geogrid.

EROSION CONTROL

Erosion control geogrids installed on steep slopes of embankments prevent in washing soil particles from surface. After vegetation, which provides erosion control of slope, becomes grown, the PP geogrid will decompose after several years.

Use of erosion control geogrids for protection of river and lake banks and sea coasts represents another method of application. So called bags (sacks) can be made of geosynthetics materials and aggregates that protect slopes against water erosion.