研究目的：过薄的道床厚度不能满足轨道结构承载能力的要求，而过高的道床厚度将增加建设成本，如何选择一个合理的道床厚度设计值在海外EPC工程中显得尤为重要，本文根据委内瑞拉Tinaco-Anaco铁路设计运营条件，以道床的累积残余变形速率作为轨道几何状态恶化及养护维修工作量的评估指标，不仅从路基基床表面承载能力和轨道整体刚度方面，而且还从后期养护维修的方面，研究比较四种不同道床厚度的优劣，从而选择一个最佳的道床厚度设计值。
研究结论：(1)轨道整体刚度是随着道床厚度的增加而增加，但增加幅度很小，道床厚度对轨道减振和弹性没有大的影响；(2)随着道床厚度增大，路基表面应力减小，道砟厚度为350 mm时，路基面应力只有 0．12 MPa，安全系数已达到1．5；(3)随着道床厚度的增大，道床振动加速度减小，道床累积变形速率随之减小，在其他条件不变的情况下，道床厚度从250 mm增加到350 mm，道床累积变形速率减小66．12％，这将极大地减少轨道养护维修工作量，延长道床使用寿命；(4)建议委内瑞拉Tinaco—Anaco铁路道床厚度为350 mm； (5)本文研究方法及结论可供类似工程参考。
Research purposes：The thiner ballast depth can not meet the requirements of track structure’s bearing capacity，while the thicker ballast depth will increase construction costs，It is very important to choose a reasonable ballast depth in overseas EPC projects．According to the operation terms in Tinaco-Anaco Railway line in Venezuela， the rate of residual track deformation is regarded as the value to evaluate deteriortion of the track geometrical state and maintaneance work in this paper．In order to define a best track depth from four kinds of ballast depth，the track quality is studied with respect to not only the bearing capacity of subgrade and track stiffness，but also the track maintaneance．
Research conclusions：(1)The track stiffness increases with the increasement of the ballast depth，but the increasement Is small．The ballast depth has little influence on the track elasticity．(2)With the increase of the ballast depth，the stress on the subgrade surface is reducing，when the ballast depth reaches 350 mm，the stress on the subgrade surface is 0．12 MPa，the safety coefficient has already been up to 1．5．(3)With the increase of the ballast depth，the acceleration of ballast is reducing，SO it is the same with the rate of residual track deformation．With other conditions no changing， When the ballast depth rises from 250 mm to 350 mm，the rate of residual track deformation reduces by 66．12％，which will reduce the maintaineance work greatly，and prolong the service life of track bed．(4)It is suggested that the ballast depth adopts 350 mm in the Tinaco—Anaco Railway line．(5)The research method and conclusion can be applied to similar projects．
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