| 摘要 |
<p>The parent patent described use of special cultivation soils sepd. from the subsoil by a water stop layer of impermeable sheet incorporating small parallel or intersecting channels or passages to carry away water draining from the cultivated levels. This addn. describes use of a plain water barrier sheet overlaid with intersecting arrays of strip profiles to provide a water drainage system which is less prone to choking. A layer of permeable felt supports the cultivation soil layer clear of the impermeable sheet and the intersecting spacers thereon. The strip profiles may be plastics profiles, opt. having a mesh structure. As before, the underlying impermeable sheet may be of e.g. polyethylene or PVC; opt. the strips may be fixed to the impermeable layer.</p> |
