The aeolian sand in the section DK111+500—DK111+800 of the Heruo Railway(Hotan-Ruoqiang)is C3 intermittent graded fine sand and cannot be directly used as filling material for railway subgrade beds.In order to improve the aeolian sand,it is considered to mix polypropylene fiber alone,as well as to mix polypropylene fiber with basalt fiber,glass fiber,and polyester fiber separately,with a mass ratio of 1∶1.Regardless of whether it is a single or complex addition,the dosage(mass fraction)is taken as 6‰,8‰,and 10‰,respectively.The cement content(mass fraction)is 5%,and the curing period is 7 d.By conducting unconfined compressive strength tests,the effects of different fiber single admixture and composite admixtures on the stress,strain,unconfined compressive strength,and secant modulus of cement modified aeolian sand was studied.The results showed that compared with single admixture specimen with the same dosage,the peak stress of composite polypropylene fiber and glass fiber specimen increases slightly at dosage of 6‰ and 8‰,while the peak stress of other composite specimen decreases.The enhancement effect of different fiber composites on the unconfined compressive strength of cement modified aeolian sand is not significant,but it has a significant impact on the secant modulus of cement modified aeolian sand.When the dosage is 8‰,the unconfined compressive strength of the composite polypropylene fiber and glass fiber specimens increases by 6.53%compared to the single admixture specimen,while the unconfined compressive strength of other composite specimens decreases by 0.21%～11.73%compared to the single admixture specimen with the same dosage.The secant modulus of composite specimens with different dosages is higher than that of single admixture specimen.When the dosage is 6‰,the secant modulus of composite polypropylene fiber and basalt fiber specimen increases by 1.12 times compared to single admixture specimen.The research results can provide reference for the improvement design and construction of surface filling materials for railway subgrade beds in desert areas.
railway subgradecomposite fiberexperimental researchcement improved aeolian sandsurface filling material of subgrade bedunconfined compressive strengthsecant modulus
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