Research On Triaxial Creep Test Of Fiber Reinforced Loess

The problem of soil rheology is a problem that generally needs to be considered in geotechnical engineering design.The rheological effect of soil is the process of soil deformation changing with time.Creep is one of the rheological effects of soil.In recent years,a large number of scholars have participated in the research.It has been shown that loess has an obvious creep effect.Fiber-reinforced loess as a new type of composite soil must have creep properties.For the creep research of fiber-reinforced loess,it can not only supplement the theory of fiber-reinforced loess,but also provide corresponding practical guidance for the improvement technology of foundation in loess area.In this paper,the consolidated drainage method was used to carry out triaxial shear creep tests on basalt fiber-reinforced loess on a loess site in Yangling.The analysis was carried out by controlling different partial stresses,initial water content,reinforcement rate and confining pressure.The creep properties of fiber-reinforced loess simulate the creep empirical equation of fiber-reinforced loess.research shows:(1)The creep deformation of loess and fiber-reinforced loess specimens increases with the increase of partial stress,and all conform to the standard creep curve type,which can be divided into 4 stages: elastic stage,attenuation creep stage,The creep stabilization stage and the constant velocity creep stage.When a low level of partial stress is applied,the soil first undergoes instantaneous elastic deformation.As the partial stress increases,it shows a tendency to attenuate creep.When the partial stress reaches a certain critical value,it shows a process of creep stability.When the partial stress increases to a certain size,the specimen enters the stage of constant velocity creep.(2)The incorporation of basalt has obvious effect on the inhibition of creep deformation of loess.The creep deformation of fiber-reinforced loess decreases first and then increases with the increase of the reinforcement rate.There is an optimal reinforcement rate.In this test,the optimal reinforcement rate is 0.25% when the creep deformation is minimum..The deformation of the fiber-reinforced loess with 0.25%,0.50%,and 1.00% reinforcement ratio relative to the plain soil is maintained at about 31%,26%,and 19%,respectively.The reinforcement effect exceeds the optimal reinforcement ratio As the reinforcement rate increases,it decreases.(3)The effect of water content on the creep of loess and fiber-reinforced loess is significant.The creep deformation,creep rate,and the time it takes for the creep to reach the stable stage of loess and fiber-reinforced loess all depend on the initial water content.As the initial moisture content increases,the reinforcing effect of fiber-reinforced loess decreases with the increase of the initial moisture content,and this trend is more obvious under low partial stress;confining pressure on loess and fiber-reinforced loess As the confining pressure increases,the creep deformation and creep rate of loess and fiber-reinforced loess decrease;the reinforcement effect of fiber-reinforced loess increases with increasing confining pressure Large,this trend is more obvious under high partial stress.(4)The stress-strain isochronous curve of loess and fiber-reinforced loess can be seen that the linear and nonlinear segments of the isochronous curve of loess are clearly delimited,while the linear and nonlinear segments of fiber-reinforced loess are difficult to distinguish.Its stress-strain curve is smooth,showing a weak hardening curve,suitable for simulation with hyperbola.(5)Based on the creep test results of the sample with a water content of 18%,a confining pressure of 100 k Pa,and a fiber content of 0.25%,the Singh-Mitchell creep empirical equation and Mesri creep empirical equation of fiber-reinforced loess are simulated.The Singh-Mitchell creep empirical equation has a high degree of agreement at low partial stress levels.As the partial stress increases,the model curve gradually deviates from the test curve and is higher than the test curve;the Mesri creep empirical equation agrees well with the test It can accurately describe the creep law of fiber reinforced loess under high confining pressure or high water content,and is not affected by the range of partial stress levels.