Analysis Of Mechanical Properties And Reinforcement Mechanism Of Fiber Reinforced Soil Under Freeze-thaw Action

As a kind of composite soil,reinforced material distributes randomly and evenly in the soil,which makes the strength and deformation of the soil approximately isotropic.It can reasonably and effectively improve some drawbacks of traditional reinforcement materials in engineering application.In order to explore the applicability of fiber reinforced technology to engineering structures in seasonal frozen region,based on theoretical analysis and experimental study,the mechanical properties of fiber-soil and the fiber reinforcement mechanism under freeze-thaw action were systematically discussed.The main research contents and results are as follows:(1)Triaxial shear tests were carried out on fiber-reinforced soil with different fiber content and fiber length under conventional conditions,and the effects of various factors on the shear strength of fiber-reinforced soil were explored.The results show that the cohesion of soil can be effectively improved when the fiber length and the fiber content are within the applicable range,but the influence on the friction Angle of soil is limited.(2)The indoor triaxial shear test was carried out after the freeze-thaw cycle to explore the reinforcement effect of fiber on soil and the influence of freeze-thaw on soil strength.The results show that the cohesion and shear strength of soil presented a decreasing trend with the increase of freeze-thaw times,and the attenuation was the most severe after the first freeze-thaw action.When the number of freeze-thaw reaches a certain value,the cohesion and shear strength of soil will no longer fluctuate greatly.The effect of freeze-thaw on the friction Angle of soil is small.The cohesion attenuation of pure soil is greater than that of fiber-reinforced soil after freeze-thaw cycle.Among the fiber-reinforced soil selected in this paper,the fiber-reinforced soil of 12mm,0.3%is the most ideal to resist the negative effects caused by freeze-thaw.(3)Based on mechanical equilibrium,the mechanism of fiber reinforcement(tensile properties,interaction between reinforcement and soil)is analyzed,and the reinforcement effect of fiber anti-tension on soil and interaction mechanism between reinforcement and soil interface are further demonstrated through crack resistance test and single fiber pull-out test.(4)Based on the characteristics of freeze-thaw conditions,combined with the strength characteristics of fiber-reinforced soil and the mechanism of fiber reinforcement,the effects of freeze-thaw on the mechanical properties of fiber-reinforced soil are comprehensively analyzed,and the strength attenuation mechanism of fiber-reinforced soil under freeze-thaw is further explained.