Titre :
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Drain envelope design under review
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Auteurs :
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W. Vlotman ;
S. Rehman ;
M. Bhutta ;
INTERNATIONAL WATERLOGGING AND SALINITY RESEARCH INSTITUTE PAK ;
International Winter Meeting ASAE, Nashville, USA, 15-18 December 1992 (1992)
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Type de document :
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article/chapitre/communication
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Editeur :
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St Joseph, USA : ASAE, 1992
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Collection :
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Paper n° 922649
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Format :
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26 p.
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Note générale :
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Sigle : ASAE
Sigle : IWASRI
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Langues:
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= Anglais
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Catégories :
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DRAINAGE
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Mots-clés:
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PAKISTAN
;
GEOSYNTHETIQUE
;
GRAVIER
;
TECHNIQUE DE DRAINAGE
;
CONDUCTIVITE HYDRAULIQUE
;
ENROBAGE
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Résumé :
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Construction of subsurface drainage systems in Pakistan have taken place at three locations since 1971. At all three locations, granular envelopes have been, and are used as a surround for the perforated PVC subsurface drain pipe. Either USBR, SCS or RRL specifications were used for the envelope design. Although designed according to the specifications, serious problems occurred with the crushed rock envelope at the drainage project near Faisalabad. An in-depth review of existing criteria revealed that the selected specifications for this particular project were on the coarser side of possible gradation specifications. In 1989 research commenced on granular and synthetic envelope design in the laboratory using permeameters, sieves, and other equipment. Preliminary results are reported. Failure of the envelopes is costly to the government both in terms of money and in time lost in solving the problems. Better design criteria are of utmost importance to Pakistan.
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