Computer microscopic test study on the suitability of modified polyimide grease used to improve collapsible loess railway subgrade

摘要

The stability and permeability of the collapsible loess are poor, and the infiltrated water in theloess is difficult to drain out.Due to the dynamic loads induced by trains, the collapsible loess railwaysubgrade is prone to instability and liquefaction. In this paper, an organic polymer material,Modified Polyimide Grease (MPG) produced was proposed to treat the collapsible loess railwaysubgrade. The scanning electron microscope, FTIR, and X-ray diffraction methods were used onthe study of the mechanism of MPG. The results indicated that an optimum MPG content of 2.5%,approximately 3 day, could achieve the highest strength and result in the best softening coefficient.After being treated by MPG, the permeability of the loess samples was slightly decreasedcompared to that of untreated samples, which indicated MPG could improve the strength of theloess without significantly reducing its permeability. This property was suitable for the subjectMPG treated loess subgrade to achieve a reasonable drainage. Besides, it is observed that someportions of pores in loess sampleswere filled by MPG and the strength between the particleswasincreased. The research results indicated that MPG is a suitable material to improve collapsibleloess railway subgrade in the subject area.