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چكيده انگليسي :

79 The effect of geotextile structural parameters on subsurface drainage clogging Reihaneh Rahimi Reihaneh rahimi@tx iut ac ir Date of Submission May 8 2016 Department of Textile Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language PersianSupervisors Mohammad Zarrebini Assoc Prof zarrebini@cc iut ac irBehrouz Mostafazadeh Fard Prof behrouz@cc iut ac irAdvisor Rohollah Rostami M Sc rohallah rostami@tx iut ac irAbstractGeosynthetics are polymeric materials that are incorporated in soil to improve the physical soil conditionsand to provide better soil drainage capability Geosynthetics are divided into five categories of geotextiles geogrids geonets geomembranes and geocomposits Geotextiles are the most important subdivision ofgeosynthetics Geotextiles are porous and permeable fibrous which usually are made of polymeric fibers Geotextiles among many other uses can be used as envelope or filter for drainpipes The geotextiles becauseof its porosity improve hydraulic performance of drainpipes and protect them from sediment The geotextilesare capable of preventing migration of soil particles into the drain which causes clogging In this study theeffects of geotextiles structural parameters on water permeability clogging and clogging changes for theneedled nonwoven geotextile samples were investigated Needled geotextile samples with various mass perunit area thickness and porosity were produced and tested using commercially available melt spun staplepolypropylene fibers These geotextiles samples were named G1 G2 and G3 Experiments were conductedusing two soil samples with different grain size distributions named S1 and S2 Based on ASTM D4833standard the resistance of the geotextile samples was determined Then the permeability of geotextilesamples and soils were measured according to ASTM D5493 standard Drainage envelopes are exposed toclogging and therefore their resistance needs to be determined Therefore a testing device which was able toevaluate the clogging potential and permeability of the samples was designed and constructed according toASTM D5101 standard Using the device the permeability of geotextile samples for both soils weremeasured The permeability were measured with time The gradient ratio which is defined as the hydraulicgradient of soil geotextile assembly to soil hydraulic gradient was used to determine the clogging potential ofgeotextiles Using currently available equations gradient ratio at each standard hydraulic gradient wascalculated and the changes in gradient ratio were determined for each geotextile samples Results showed thatG2 geotextile which has the highest mass per unit area and thickness in comparison to other samples has thehighest resistance and the lowest permeability The increase in hydraulic gradient caused reduction ininfiltration for the samples Results showed reduction of the geotextile permeability due to increase in themass per unit area Utilization time tended to reduce permeability of the geotextile soil assembly Theincrease in utilization time leads to increase gradient ratio The G 1 and G2 geotextiles which had gradientratios greater than unity easily clogged The G 2 geotextile as compared to the G1 geotextile clogged faster The G3 Geotextile which requires fewer punch density due to gradient ratio smaller than unity is moresuitable for drainage of sample soils Keywords Geotextile Drainpipe Envelope Clogging Permeability Gradient Ratio

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تاثير عوامل ساختاري ژئوتكستايل بر انسداد زهكش هاي زيرزميني

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