一、概况 世界上以枕木和道床为轨下基础的轨道结构已有一百多年的历史。目前,许多国家已经大量采用各种型式的钢筋混凝土轨枕。但所有这些轨枕都保留了木枕的特点,即它们都是条状的,都按一定间距铺设。随着铁路运输的发展,行车速度和密度的提高,这种传统的轨下基础逐渐暴露出它的缺点,即其支承面积较小,在列车动荷载作用下,逐渐发生较大的永 I. Overview The orbital structure based on sleepers and ballast beds in the world has a history of over one hundred years. At present, many countries have extensively adopted various types of reinforced concrete sleepers. All of these sleepers, however, retain the characteristic of wooden pillows, that is, they are strip-shaped and laid at regular intervals. With the development of railway transportation, the increase of traffic speed and density, the traditional rail-based foundation gradually reveals its shortcoming, that is, its supporting area is relatively small. Under the action of train dynamic loads, great Yong