Experimental on effect of filler particle gradation on pullout characteristics of denti-geogrid
In order to study the effect of particle size distribution of fillers on the pullout characteristics of denti-geogrids,four types of fillers were prepared from standard sand,well graded sand and poorly graded coarse/medium/fine sand,and the angle aluminum and geogrids were assembled into denti-geogrids using zip ties.The geogrids were classified into two categories,biaxially stretched plastic geogrids and polyester warp knitted geogrids.Subsequently,two denti-geogrids were emplaced in four kinds of sandy fillers with a water content of 0.5％and a compaction degree of 95％.The YT geosynthetic material friction tester was used to conduct pull-out model tests under different normal stresses(10 to 60 kPa)and tooth heights(0 to 10 mm).The results show that due to the thick transverse ribs of the biaxial stretched plastic geogrid,when the content of coarse particles(mass ratio)of the filler is high,the sand particles at the narrow gap of the model box are not capable to be discharged smoothly,which may lead to small fluctuations on the pullout force-pullout displacement(T-△L)curve.With the increase of tooth height and coarse particle content,the pullout force,pseudo cohesion,and pseudo friction angle of two types of denti-geogrids both increase,while their influence on pseudo cohesion is much greater than that on pseudo friction angle.The influence of particle size distribution and tooth height on the interfacial cohesion of toothed biaxially stretched plastic geogrids is much higher than that of toothed polyester warp knitted geogrids.The quasi friction coefficients of two types of denti-geogrids increase with the growth of coarse particle content,while the pullout coefficient is negatively correlated with the coarse particle content of the filler.Under the same working conditions,the characteristic values of the pullout force,interfacial shear parameters,quasi friction coefficient,and pullout coefficient of the toothed biaxially stretched plastic geogrid are greater than those of the toothed polyester warp knitted geogrid.Therefore,for sandy filler,the former has a better reinforcement effect,and the use of toothed plastic geogrids can better improve the interface friction characteristics.In the application of reinforcement engineering,toothed biaxial stretched plastic geogrid ought to be priorly adopted.6 tabs,12 figs,25 refs.
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