Abstract:In Shandong Province, silt is widely distributed in the Yellow River flooding area. In the case of shortage of railway roadbed filling, improved silt is commonly used as roadbed filling. Using nano-silica and lime as modifiers, the silt in the Yellow River floodplain area was improved. The strength of the silt was measured by compaction test and unconfined compressive strength test. It was found that although the strength of the silt improved by nano-silica-lime was significantly improved, it also showed the bad characteristics of brittleness. For the present nano-silica and lime improved silt, the strength of the improved silt has been significantly improved, but it also shows the bad characteristics of brittleness. In order to improve the brittleness of silt improved by nano-silica-lime, polypropylene fibers were added to the improved silt and the effects of fiber content and length on the strength and brittleness of the silt improved by nano-silica-lime were studied through a series of experiments, and the optimum fiber content and the optimum fiber content were determined. The results show that the brittleness and compressive and shear strength of the silt improved by nano-silica-lime can be improved by adding fibers;and when the content of fibers is 0.4% and the length of fibers is 2 cm, the improvement effect is the best.