中文摘要：

研究目的：随着青藏铁路的开通,钢轨钢材在低温下安全性能研究的重要性随之凸现出来。为了防止钢轨钢材在低温条件下发生脆性断裂,提出一种实用的钢轨钢材低温下防断设计方法具有重要的现实意义。研究结论：钢轨钢材在低温下属于较为典型的脆性断裂,低温防断设计方法是以试验测量得到的平面应变断裂韧度KIC作为安全分析判据;从工程实际出发,进行低温下钢轨的抗断设计,得出钢轨常见裂纹的容许裂纹上限值aC,为钢轨的伤损检测提供了依据。

英文摘要：

Research purposes：With the Qinghai-Tibet Railway open to traffic,it becomes more and more important to do the research on the safety properties of rails under low temperature.To prevent the brittle fracture of rails under low temperature,a practical design method for rail fracture-resisting is of greatly realistic significance.Research conclusions：At low temperature,the fracture of rails steel is of typical brittle fracture.Based on the plane stain fracture toughness KIC obtained by experiments,the practical fracture-resisting design method is given.For the common crack of the rails,the upper limit of the allowable crack ac is obtained for providing the basis for the damage detection.