Study On The Interfacial Friction Characteristics Of Reinforced Red Soi

This paper is based on the project of National Natural Science Foundation of China,"Research on Engineering Performance and Ontological Model of Reinforced Laterite"(Project No.59968002).Geotextiles,geogrids and glass fibers were used as reinforcing materials,and the effect of initial dry density,initial moisture content and shear rate were taken into account to conduct a direct shear friction test to study the interfacial friction characteristics of reinforced laterite under different influencing factors.The following results were obtained.Interfacial friction stress-displacement characteristics of reinforced laterite: Under the condition of straight shear friction test,with the increase of friction displacement,the interfacial friction stresses of three kinds of reinforced laterite and plain laterite of geotextile,geogrid and glass fiber under different influencing factors showed a rapid increase-slow increase trend,showing the strain hardening characteristics.In general,with the increase of initial moisture content,the positions of interfacial friction stress-displacement curves of geotextile,geogrid and glass fiber reinforced laterite fluctuate down and the inflection point shifts to the right,correspondingly the interfacial friction stress decreases and the friction displacement increases;the positions of interfacial friction stress-displacement curves of plain laterite fluctuate down and the inflection point shifts to the left,correspondingly the interfacial friction stress and friction displacement decrease.With the increase of initial dry density,the position of interfacial friction stress-displacement curve of geotextile,geogrid and glass fiber reinforced laterite fluctuates higher,the inflection point shifts right,and the corresponding interfacial friction stress and friction displacement increase;the interfacial friction stress-displacement and interfacial friction stress of plain laterite show fluctuating changes,the inflection point shifts left,and the friction displacement shows a decreasing trend.With the increase of shear rate,the positions of the interfacial friction stress-displacement curves of both geogrid and glass fiber reinforced laterite fluctuate lower,the inflection point shifts right,the corresponding interfacial friction stress decreases and the corresponding friction displacement increases;the positions of the interfacial friction stress-displacement curves of geotextile reinforced laterite fluctuate lower,the inflection point shifts left,the corresponding interfacial friction stress and friction displacement fluctuate lower;the interfacial friction stress-displacement curves of plain laterite The position of interfacial friction stress-displacement curve of plain red soil fluctuates up and the inflection point shifts to the left,and the corresponding interfacial friction stress fluctuates up and friction displacement fluctuates down.Interfacial friction strength characteristics of reinforced laterite: with the increase of initial water content,the interfacial friction strength and interfacial damage displacement of three kinds of reinforced laterite showed decreasing changes;the interfacial friction strength and interfacial damage displacement of plain laterite showed decreasing changes.With the increase of initial dry density,the interfacial friction strength of geotextile and glass fiber reinforced laterite both showed increasing changes,and the interfacial damage displacement showed increasing changes when the initial moisture content was higher and the shear rate was lower;the interfacial friction strength and interfacial damage displacement of geogrid reinforced laterite both showed increasing changes;the interfacial friction strength and interfacial damage displacement of plain laterite both showed decreasing changes.With the increase of shear rate,the interfacial friction strength and interfacial damage displacement of geotextile-reinforced laterite showed decreasing changes;the interfacial friction strength and interfacial damage displacement of both geogrid and glass fiber-reinforced laterite showed decreasing changes and interfacial damage displacement showed increasing changes;the interfacial friction strength of plain laterite showed increasing changes and interfacial damage displacement showed decreasing changes.Interfacial friction strength index characteristics of reinforced laterite: with the increase of initial water content,the interfacial cohesion of geotextile reinforced laterite fluctuates and the interfacial friction angle fluctuates;the interfacial cohesion and interfacial friction angle of geogrid,glass fiber reinforced laterite and plain laterite both fluctuate and decrease.With the increase of initial dry density,the interfacial cohesion and interfacial friction angle of geotextiles and geogrids fluctuate;the interfacial cohesion and interfacial friction angle of glass fiber reinforced laterite fluctuate;the interfacial cohesion and interfacial friction angle of plain laterite fluctuate.With the increase of shear rate,the interfacial cohesion and the interfacial friction angle of geotextile-reinforced laterite fluctuate;the interfacial cohesion of geogrid and glass fiber-reinforced laterite fluctuate and the interfacial friction angle fluctuates;the interfacial cohesion of plain laterite fluctuates and decreases,and the interfacial friction angle fluctuates and increases.Reinforcement effect of the three materials: Under different influencing factors such as initial moisture content,initial dry density and shear rate,all three materials can improve the interfacial friction strength characteristics of the soil as well as the friction strength index as far as the reinforcement effect of the three reinforcing materials is concerned.In general,the reinforcement effect of glass fiber is the best,and the reinforcement effect of geotextile and geogrid is the second best.