| 摘要 |
To make an oriented plastics material geogrid (10) in which oriented strands (6, 9) form triangular meshes with a junction (11) at each corner and six of the strands (6, 9) meet at each junction (11), a plastics material sheet starting material has holes in an array of hexagons, opposite holes of each hexagon being aligned in the machine direction, and the starting material is stretched first in the machine direction and secondly in the transverse direction. In the eventual geogrid (10), the centre portions of the hexagons in the starting material form the junctions (11). The centres of the junctio ns (11) are slightly biaxially oriented, but at the edges of the junctions (11) , the orientation of the edge of substantially each strand (6) or (9) runs around the edge of the respective junction (11) and into the edge of the nex t strand (6) or (9). During the second stretch, restraint can be applied in th e first stretch direction and discontinued before the material is allowed to relax in the second stretch direction. If desired, the procedure can be terminated after the first stretch, to produce a uniaxially-oriented geogrid . By using a starting material which has through holes and weakened zones, it is possible to form the geogrid of the invention from a starting material havin g a rectangulararray of through holes. |
