Study On The Strength Change Of Fiber Reinforced Soil Based On The Optimal Moisture Content

A large number of previous studies have shown that adding a certain proportion and length of fibers to the soil will improve its shear strength.This artificially modified composite soil is called fiber reinforced soil.Polyester and nylon fibers,as a common synthetic waste,have a huge annual output.If they are reused and mixed into loess,the strength of the soil can be improved.In this paper,polyester and nylon fibers of different length and content are added into Loess and mixed evenly to make reinforced soil samples.The length is 5mm,10 mm,30 mm and 50 mm respectively,and the content is 0.1%,0.2%,0.3% and 0.4%,totally 32 samples.The indoor triaxial test(UU)was carried out on the above samples,and the shear strength indicators-cohesive force(c)and internal friction angle(?)were measured,and compared in various dimensions.The research results are as follows:(1)The stress-strain curve of polyester fiber reinforced soil is similar to that of nylon fiber reinforced soil.Most of them are hardened type.At low confining pressure of 100 kPa and a short fiber length,several of them are close to the ideal plastic type;under normal circumstances When the fiber length and content are the same,the slope of the stress-strain curve increases with the increase of the confining pressure.(2)For cohesion: when the fiber length is constant,the cohesion of the two fiber reinforced soils generally increases gradually with the increase of the content;when the fiber content is constant,the two fibers are reinforced The cohesion of the soil generally increases first and then decreases with the length.(3)For the internal friction angle: when the fiber length is constant,the internal friction angle of the polyester fiber reinforced soil generally decreases with increasing content,and the internal friction angle generally decreases after increasing with the content.Increasing;when the fiber content is unchanged,the internal friction angle of the two fiber reinforced soils decreases first and then increases with the general content of the content,and decreases with respect to the remolded soil without fiber.(4)When the fiber length is 10 mm and 30 mm,the internal friction angle of the polyester fiber soil is greater than that of the nylon fiber reinforced soil;and when the fiber length reaches 50 mm,the internal friction angle of the nylon fiber reinforced soil is greater than the polyester fiber plus The internal friction angle of the soil.(5)When the fiber content is 0.1%,the internal friction angle of nylon fiber reinforced soil is greater than that of polyester fiber reinforced soil;when the fiber content increases to 0.2% and 0.3%,the internal friction angle of polyester fiber reinforced soil The angle is greater than the internal friction angle of nylon fiber reinforced soil.When the fiber content is 0.2% and 0.4%,the cohesion of polyester fiber reinforced soil is greater than that of nylon fiber reinforced soil.Therefore,on the whole,when the fiber content is 0.2%,the shear strength of polyester fiber reinforced soil is greater than that of nylon fiber reinforced soil.