To solve the problems of the rail fracture during straightening,bloom fracture and over-firing that occured at the beginning of commercial production of high carbon microvanadium PD_3 steel rail recently developed by Pangang,macroscopic observation and metallographic study are used to analyze the main mechanisrns for the material failure.

Based on caculation of three-dimensional finite element method and field ob-servatiOn results,this paper studies the antielasticity mechanism,affecting factors and the re-lation between abutment characteristics and roof breaking and discusses the engineering signifi-cance of anti-elasticity.