Geosynthetics

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Introduction

Geosynthetics have been widely used in geotechnical and environmental engineering for the last 4 centuries ,these products helped in construction engineering field specially in the construction of conventional construction materials that were restricted or very expensive.

The advances on the use of geosynthetics materials in reinforcement and in environmental protection:

there are common types of geosynthetics used for soil reinforcement include geotextiles ,geogrids and geocells. Geotextiles are continous sheets of woven, nonwoven, knitted or stich-bonded fibers or yarns. The sheets are flexiable and permeable and looks like a fabric. Geogrids have a uniformaly distributed array of apertures between their longitudinal and transverse elements. These apertures allow direct contact between soil particles on either side of the sheet. Geocells are thick, three-dimensional networks constructed from strips of polymeric sheet. The strips are connected together forming a net cell that is filled by soil or concrete. In some cases 0.5m to 1m wide strips of polyolefin geogrids are linked together with vertical polymeric rods used to form deep geocell layers called geomattresses.

There are many types of geosynthetics products can be used in environmental protection projects,including geomembranes, geosynthetic clay liners (GCL), geonets, geocomposites and geopipes. Geomembranes are continuous flexible sheets manufactured from one or more synthetic materials. They are impermeable and used as liners for fluid or gas containment and as vapour barriers. Geosynthetic clay liners (GCLs) are geocomposites that are prefabricated with a bentonite clay layer typically incorporated between a top and bottom geotextile layer or...

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...il as the backfill if necessary.

The use of relatively short reinforcement.

The staged construction method (Fig. 8), which is one of the main features of this RW system,

consists of the following steps:

1) a small foundation element for the facing is constructed

2) a fullheight GRS wall with wrapped-around wall face is constructed by placing gravel-filled bags at the shoulder of each soil layer and

3) a thin (i.e., 30 cm or more in the thickness) and lightly steelreinforcedconcrete facing (i.e., a FHR facing) is constructed by cast-in-place fresh concrete directly on the wall face after the major part of ultimate deformation of the backfill and the subsoil layer beneath the wall has taken place.

A good connection can be made between the RC facing and the main

body of the wall by placing fresh concrete directly on the geogrid-covered wall face.

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