Geotextiles tendencies

Zone 2 soils consist of coarse silts and fine sands (dg5 > 0.075 mm and djo < 0.6 mm) and these exhibit an increased tendency for the movement of fine soil particles. They are considered to be problem soils with regard to geotextile filters. Table 8.5 shows that the AOS requirement for retention has a smaller range than for Zone 1 soils. 

As with the puncmre requirement just described, the resistance of a geotextile to impact is as much a survivability criterion as it is a separation function. Yet in many instances of separation the geotextile must resist the impact of various objects. The most obvious one is that of a heavy object falling on it, but there are also simations in which construction equipment and materials can cause or contribute to impact damage on geotextiles. Once an impact causes a hole, the tendency of the geotextile is to tear in its weakest direction. 

Nonwoven geotextile—geonet composites show larger transmissivity without compressive stress but a rapid decrease with compressive stress. This tendency of transmissivity decrease results from a decrease in the pore size of fiber assemblies in nonwoven geotextUes and an increase in the fiber density per constant area. Also, nonwoven geotextile—geonet composites have a decrease in thickness with compressive stress this tendency can be improved by the special composition of geotextile composites. 

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