بررسي خواص هيدروليكي ژئوتكستايل هاي سوزن زني شده

چكيده انگليسي :

Investigation of Hydraulic Properties of Needle Punched Geotextiles Hasan Shokrollahi hasan shokrollahi@gmail com Date of Submission march 12 2012 Department of Textile Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiMohammad zarrebini m zarrebini@cc iut ac irAbstractGeo textiles are an important part of geo synthetics group of materials Geo textiles are extensively utilized in civilengineering projects Geo textiles fulfill various functions required by civil engineering criteria due to their variedproperties Hydraulic Properties of geo textiles is of paramount importance in civil engineering projects In thisresearch cross plan permeability of nonwoven needled geo textile fabrics was investigated Samples of geo textilematerials were made using commercially melt spun polypropylene fibers An apparatus capable of measuring cross plan permeability under zero normal stress confinement was made according to ASTM D4491 standard Thesamples of geo textile materials were produced using two stage needle punching process in which productionparameters such as mass per unit area punch density and thickness were varied Hydraulic experiments wereconducted according to both constant and falling head test methods under linear flow condition Cross planpermeability is characterized by the coefficient of permeability according to Darcy s law Permeability of theexperimental geo textile samples were compared to the permeability of conventional granular civil engineeringmaterials Based on the results it was concluded that such thin and light geo textiles can successfully replaced thickand heavy conventional granular materials The effect of factors such as fabric thickness the amount of punchdensity fabric porosity and weight on cross plan permeability of nonwoven needled geo textile fabrics together withrelationship between minor losses coefficient and friction factor with Reynolds number were studied Theexperimental samples of geo textiles were produced at constant needle penetration of 13 mm It was found thatreduction of punch density imparted to geo textiles caused the fabric thickness to be increased The effect of geo textile thickness on fabric permeability in relation to punch density was also investigated It was concluded thatincreases in geo textiles thickness correspondingly increases the fabric opening size This in turn enhances thefabric permeability Punch density also affects fabric permeability Results showed that fabric permeability isreduced when the amount of punch density is increased This may be due to the existence of an inverse relationbetween punch density and fabric porosity It was found that degree of compactness of fabric increases withincreases in the amount of punch density The increase in fabric compactness results in reduction of the porosity ofthe fabric thus the observed reduction in the permeability of the samples The results showed that permeability ratedecreases as weight per unit area of geo textile is increased The increase in the weight per unit area of geo textile isdue to the increase in the number of fibers present the fabric structure This leads to increases in the flow path lengthand resistance These are in accordance to the modified Kozeny equation which confirms the reduction ofpermeability of fabric Representation of experimental data on log log paper showed a negative linear relationshipbetween friction factor and Reynolds number Graphical relationship between minor losses coefficient and Reynoldsnumber was also provided This plot showed that geo textiles sample with higher permeability exhibit smallerminor losses Comparison of results obtained in this research with the previous studies in relation to the effect offactors such as thickness porosity weight per unit area and punch density on the permeability showed acceptableagreement Keywords Geo textiles Geo synthetics Hydraulic Properties Permeability Punch density Constant and FallingHead Test Linear Flow

شكراللهي، حسن

بررسي خواص هيدروليكي ژئوتكستايل هاي سوزن زني شده

ژئو سنتيك ها , خصوصيات هيدروليكي , نفوذپذيري , آزمايش بار آبي ثابت و افتان , جريان خطي , قانون دارسي و مصالح دانه اي