Experimental Study On Mechanical Properties Of Cemented Soil Reinforced By PVA Fiber

Cemented soil has been widely used in slope reinforcement,soft soil foundation treatment,waterproof curtain and other geotechnical engineering projects owing to the merits of low price,convenient construction and little impact on the environment,which brings good economic and environmental benefits to the project construction.However,in the practical application of engineering,cemented soil often causes serious engineering accidents due to its insufficient strength and poor ductility.In addition,the tensile strength of cemented soil is often neglected in engineering.In some specific cases,the horizontal loads can give rise to macro-cracks and fail in tension,hence,the random distributed fibers are utilized to prevent the occurrence and propagation of cracks and improve the mechanical properties.In this study,PVA fibers were opted for fiber reinforcement in cemented soil to improve the mechanical properties and brittle failure pattern due to its characteristics of high tensile strength and modulus,easy dispersibility.Through a series of tests on 17 groups of polyvinyl alcohol fiber cement soil specimens,this paper makes a comparative analysis on the strength,stress-strain relationship,deformation modulus,toughness,failure mode and compression performance of PVA fiber cement soil.Furthermore,the impact of different fiber length and content of polyvinyl alcohol fiber on various physical properties of cemented soil,along with the mechanism of PVA fiber reinforcement in cemented soil were evaluated.The conclusions are as follows:(1)Through the unconfined compressive strength test,it is shown that the addition of PVA fiber can improve the unconfined compressive strength of cement soil to a certain extent.The influence of fiber length,content and age on the compressive strength is analyzed,and the relationship between unconfined compressive strength and deformation modulus is established.(2)Through the uniaxial tensile strength test,it is shown that the incorporation of PVA fiber can significantly improve the tensile strength of cemented soil.The typical stress-strain curve of fiber reinforced cemented soil is analyzed,and the impact of fiber length,dosage and curing age on the tensile strength is discussed.The incorporation of fiber can obviously improve the toughness of cement soil,which makes the fiber cement soil "crack" when it is damaged the relationship between tensile strength and compressive strength of fiber cement soil is analyzed.(3)Through one-dimensional compression test,it shows that the compression coefficient of cemented soil with inclusion of PVA fiber is less than 0.1,which belongs to low compressibility soil.The compression coefficient cc of PVA fiber reinforced cemented soil is inversely correlated with the compressive strength,the compression coefficient decrease with the increase of compressive strength.(4)Based on the SEM test and the mechanical test results,the reinforcement mechanism of PVA fiber is illustrated with two impact factors,which includes frictional reinforcement and equivalent confining pressure.