Geosynthetics separation

The primary objective of a liner, or barrier layer, is to prevent or reduce the migration of potentially harmful chemicals, or contaminants, into the strrrotmding environment. With respect to this objective, several different types of liners are ttsed for the containment of waste. As outlined in Table V, the different types of liners may be separated into three broad classifications (1) earthen (soil) liners, (2) geosynthetic (polymer) liners, and (3) composite liners. Earthen liners may be further divided into natirrally occtrrring low-permeability soil liners and manmade liners (e.g., compacted or mechanically stabilized low-permeability soils). 

Composite liners are combinations of soil liners and/or geosynthetic materials. The properties of composite liners are essentially the same as the component materials for the composite liner. However, animpoitant aspect for the effective use of composite liners is that the composite materials must be in intimate contact (i.e., without separation between materials). In reality, the type of GCL shown in Fig. 9c is a manufactured composite liner. Composite liner systems typically are used in conjunction with municipal and hazardous solid waste disposal. 

Geosynthetics have been used in new road construction in various ways to minimise the previousiy mentioned probiems as weii as in the maintenance of existing paved roads (overiays appiied to strengthen existing pavements). In this category of application the two principal roles for geosynthetics are separation/filtration, and reinforcement. The use of geosynthetics to perform these functions in unpaved and paved roads is discussed in Section 5.1.3.1 and 5.1.3.2. 

The fields of application of geosynthetics can be eharacterised by the terms separation, protection, filtration, drainage, reinforcement, containment and sealing. 

Table 19.1. Design requirements for geosynthetics with a filter and separation function.

Decoupled Analysis Most seismic analyses of landfill systems conducted in practice today employ a decoupled approach in which the response of the landfill to the seismic loading is considered separately from integrity assessments for the waste mass and containment system components. The seismic response analysis is conducted assuming that the containment system components and waste mass maintain their integrity, that there is no relative displacement at geosynthetic interfaces, and that no instabdities develop. The most common type... 

The functions generally attributed to geosynthetic products are separation, filtration,... 

Flgnre 11.7 Geosynthetic Institute s ongoing roadway separation study. 

Drainage composite (chimney drain) Geosynthetic reinforcement Geotextile separator/fllter... 

The versatility of geotextiles as separators can be coupled well with other geosynthetics and even with soil to form a composite material. Common examples are as follows ... 

With the development of geosynthetics, great achievements have been made in improving foundation soils. As a result of this, nearly all functions of geosynthetics can be used reinforcement, separation, filtration, and drainage. 

GRI (www.geosynthetic-instimte.org) has published standard guides for nonwoven geotextiles used for either cushioning or separation applications for both ASTM and... 

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