DRAINAGE MEMBRANE AND INSTALLATION METHOD

摘要

The invention relates to a dimple sheet drainage membrane construction and method for its installation, for example in a tunnel bore (10) or other excavated substrate surface. The membrane sheet (20) has dimpled portions creating a drainage space on one side of the sheet and non-dimpled edge regions (26) and interior regions (24) for facilitating joining and to form an array of fixing locations (28) for non-penetrative fixing to the underlying substrate. The invention also relates to a fixing method for a drainage sheet using an array of plate-like fixing discs (30) secured to the substrate surface at locations corresponding to the fixing locations of the sheet and non-penetrative fixing means for securing the sheet, and to a fixing pattern for securing the sheet to the tunnel bore.