求翻译：混凝土枕端部埋入道床深度为15cm,中部60cm范围内道床顶面应低于枕底3cm。轨道的碴为碎石，如碎石道碴取材困难，可选用铁路道碴技术标准中规定其它种类道碴.是什么意思？

Concrete sleeper end buried in the depth of the track bed 15cm, bed top surface of the central 60cm range within the Road should be lower than the pillow end of 3cm. Track ballast of crushed stone, gravel ballast material difficulties, the choice of railway ballast technical standards specified in o

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The concrete pillow nose buries the bed depth is 15cm, middle in the 60cm scope the bed top should be lower than pillow bottom 3cm.Orbital being cut by broken glass for crushed stone, if the crushed stone ballast selection difficulty, may select in the railroad ballast technical standard to stipulat

Buried depth of 15cm to become a monk bed sleeper ends, Central 60cm range road bed pillow top surface should be lower than the end of 3cm. Track ballast is crushed stone, such as ballast material difficulties, the choice of technical standards in the railway ballast under other types of ballast.

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