Study On Reinforcement Characteristics And Improvement Methods Of Geotextile

Geotextiles are one of the early applied reinforced materials.In recent years,the tensile strength of geotextiles has become increasingly high.In order to better play its role in reinforced structures,this paper proposes a sewn transverse ribbed geotextile reinforced structure,which is studied based on the experimental study of the interaction characteristics of the reinforcement soil interface.A large size direct shear instrument is used to consider the influence of geosynthetic material type and normal stress on the mechanical properties of the reinforced soil interface,and discrete element numerical simulation analysis is carried out on the direct shear test of the reinforced soil interface.The macro and microscopic characteristics are linked together,the test results are analyzed from multiple angles,the test is timely fed back,and the reinforcement method is adjusted and optimized.It provides technical reference for engineering application of reinforced earth retaining wall of this structure form.Major areas of research include:(1)Starting from the basic characteristics of geotextiles,different geotextiles were selected for strip stretching tests,and based on the results,a geotextile with better performance was selected for follow-up tests.According to comprehensive strength and elongation analysis,geotextile B has significant advantages,which can not only meet the requirements of strength in the test process,but also meet the requirements of deformation.(2)By direct shear test between geosynthetics and sand using large direct shear instrument,the influences of different geosynthetics,different shear rates and different normal stresses on mechanical properties of reinforced soil interface are analyzed.According to the above test results,geotextile with good performance was selected to take sutured transverse rib reinforcement and conduct direct shear test,so as to analyze the mechanical characteristics of the reinforced soil interface of the bottom geotextile,transverse rib and joint under different test conditions.Through a series of large-scale direct shear tests,it has been concluded that the interface properties of geotextile-sand soils are not as good as those of geodesics in the presence of tiling reinforcement.The shear strength of the stitched rib reinforced structure is greatly enhanced,and the peak value of the shear strength is reached only after a certain shear shift occurs.The reinforcement mechanism is reflected in the friction and interlock between the soil mass and the underlying fabric,as well as in the transverse restraint and friction of the rib on the fill.(3)In terms of numerical simulation,the corresponding discrete element model is established by PFC2 D particle flow numerical simulation software,and relevant mesoscale parameters are calibrated according to laboratory test results to simulate soil particles from a mesoscale perspective,reducing the difference between numerical simulation and laboratory test.After the shear box is applied with a rightward velocity,the direction of the force chain changes from vertical to leftward tilt,and the left side of the force chain is large and dense,while the right side is small and sparse.The direction of the force chain near the transverse rib is essentially perpendicular to the transverse rib.The force chain distribution in the left side of the transverse rib is dense,and the force chain distribution in the right side is sparse.At the end of the shear,a curved shear band is formed at a distance of 50～150 mm from the underlying geotextile,and the thickness of the shear band increases with the increase of the number of transverse ribs and the height of transverse ribs.