Abstract: To investigate the influence of fiber forms on the strength and deformation characteristics of cement loess, the cement loess mixed with three different types of polypropylene fiber (bunched monofilament fiber, mesh fiber, and stranded fiber) was studied by direct shear, static triaxial and SEM tests. The experimental results show that: (1) the addition of three kinds of fibers can effectively improve the shear strength and cohesion of cement loess, and the cohesion of three kinds of soils increases first and then decreases with the increase of the content of dimension. The optimal content of stranded, reticulated and bunched monofilament fibers is 0.3%, 0.35% and 0.55%. (2) The strength and deformation characteristics of modified cement loess with stranded fiber and mesh fiber are different in direct shear test and triaxial test. (3) The three-dimensional network structure of the network fiber can effectively restrain soil deformation and improve soil strength in the triaxial test; The strong deformation resistance of the stranded fiber can play a good role in the direct shear test. (4) The interfacial friction between fiber and soil plays an important role in the improvement of cement loess with three kinds of fibers. Stranded fibers mainly improve soil strength through their good resistance to deformation. 

Key words: fiber form, cement-modified loess, strength and deformation, microscopic mechanism