Geomembrane Puncture Protection, Geotextile Selection - Design Calculator
There are many circumstances where geomembranes
are placed on or beneath soils containing relatively large-sized stones. For
example, poorly prepared soil subgrade with stones protruding from the surface,
and cases where crushed-stoned drainage layers are to be placed above the
In all of these situations, a nonwoven needle-punched geotextile can provide significant puncture protection to the geomembrane. The issue of determining the required mass per unit area of the geotextile becomes critical.
The method presented herein (Koerner, 1998) focuses on the protection of 1.5 mm thick HDPE geomembranes. The method uses the design by function approach.
|FS||factor of safety against geomembrane puncture|
|Pact||actual pressure due to the landfill contents or surface impoundment|
|Pallow||allowable pressure using different types of geotextiles and site specific conditions.|
pallow is determined by the following equation:
|M||geotextile mass per unit area||g/m2|
|H||height of the protrusion above the subgrade||m|
|MFS||modification factor for protrusion shape||-|
|MFPD||modification factor for packing density||-|
|MFA||modification factor for arching in solids||-|
|RFCR||reduction factor for long-term creep||-|
|RFCBD||reduction factor for long-term chemical/biological degradation||-|
|Subrounded:||0.5||Dense, 38 mm||0.83||Geostatic, shallow||0.75|
|Rounded:||0.25||Dense, 25 mm||0.67||Geostatic, mod.||0.50|
|Dense, 12mm||0.50||Geostatic, deep||0.25|
|Mild leachate||1.1||Geomembrane alone||N/R||N/R||N/R|
Wilson-Fahmy, R.F., Narejo, D. and Koerner, R.M. (1996), "Puncture Protection of Geomembranes Part I: Theory", Geosynthetics International, Vol. 3, No. 5, pp. 605-628.
Narejo, D. and Koerner, R.M. and Wilson-Fahmy, R.F., (1996), "Puncture Protection of Geomembranes Part II: Experimental", Geosynthetics International, Vol. 3, No. 5, pp. 629-653.
Koerner, R.M., Wilson-Fahmy, R.F. and Narejo, D. (1996), "Puncture Protection of Geomembranes Part III: Examples", Geosynthetics International, Vol. 3, No. 5 pp. 655-675.
Koerner, R.M. (1998), Designing with Geosynthetics, Prentice Hall Publishing Co., Englewood Cliffs, NJ.
Copyright 2001 Advanced Geotech Systems. All rights reserved.