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چكيده انگليسي :

An Investigation on Anisotropic Permeability of Soils Mohammad Ghanbar Dezfuly Mghd2005@gmail com May 16 2009 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiM A Rowshanzamir mohamali@cc iut ac irAbstractAnisotropy in engineering materials is defined as having unlike properties in different directions Considering theconstruction of earth structures and energy induced compaction in vertical direction the anisotropy is anunavoidable fact The anisotropy of permeability in soils has been a well known field since the past time but therehave been a few attempts to be accounted for in the geotechnical design Because considering of this anisotropy needs a lot of time and cost for measuring the properties of materials It is obvious that modification the data fromisotropic assumption to the anisotropic real behavior leads to more precise and economical design However in the recent decade the availability of high speed computers and development of numerical softwares hasmade it possible to account for the anisotropy in the design process But until now little progress has been made inthe development of experimental methods for measuring anisotropic properties of geomaterials In the presentstudy an attempt has been made to modify the experimental apparatus of measuring the permeability in order toevaluate the anisotropic properties of cohesive frictional soils Using more than 126 tests on selected samples fromcohesive frictional soils the effect of compaction type the compactions moisture ratio ratio of compaction and theclay fraction have been evaluated In this study a sandy clay soil with gravel has been used The most important reasons for selecting this soil are itsavailability and being the first alternative for construction of homogenous earth dams Compaction and its affectingfactors i e moisture content compaction type level of compaction as well as the clay fraction are the mostimportant parameters in anisotropic properties of soils Thus the effect of these parameters has been investigated inthis research study The samples have been prepared at three different moisture content i e 6 9 and 12 In vibration compaction samples with compaction ratio equal to 95 100 and 105 relative to standard compaction ratio and with clayfraction equal to 10 15 and 20 have been used In order to evaluate the effect of compaction type on theanisotropy of permeability in vibration compaction static compaction the samples with clay fraction equal to 15 with dry density equal to maximum dry density have been used Also for investigation of effect of clay fraction onthe anisotropic properties of permeability only the vibration compaction has been used From the experimentalresults it has been seen that there is anisotropy in all samples As the moisture content of compaction increases thepermeability in the soil is decreased and the anisotropy has the increasing progress Also increasing the dry densityto maximum dry density leads to increase in the anisotropy Furthermore making density more than maximum drydensity leads to decrease in the anisotropy The minimum anisotropy has been seen in vibration compaction whilemaximum anisotropy was with static compaction Also as the soil fine fraction increased the anisotropy ofpermeability increased Key WordsAnisotropic Permeability Compacted Soil Fine Fraction Moisture

دزفولي، محمدقنبر

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