The coupling calculation model of tunnel and surrounding rock is established by the finite difference method, and the main design parameters of lining structure of single-track ballasted tunnel under 40-ton axle load, heavy train load, are studied in combination with cumulative damage mechanism of surrounding rock at tunnel bottom and the fatigue life characteristics of concrete structure at tunnel bottom. The results show that (1) inverted arch shall be set in sections of III-grade and above. Whether an invert is set in sections of II-grade and below shall be determined according to lithology and groundwater conditions. When the surrounding rock condition is good and the tunnel bottom structure (without invert structure) is adopted, the thickness is recommended to be more than 20 cm, and the concrete strength grade should not be lower than C35. (2) Connection mode: the inverted arch and side wall of the tunnel should be connected in sequence to reduce the stress concentration and improve the stress state of the connection part between the inverted arch and the side wall. (3) It is suggested that the rise-span ratio of invert of single-track tunnel should be 1/6 ∼ 1/8; the larger value should be taken when the surrounding rock condition is poor and the small value should be taken when the surrounding rock condition is good. (4) The thickness of inverted arch is recommended to be no less than 20 cm under the condition of V-grade surrounding rock, to be no less than 15 cm under IV-grade surrounding rock, and to be no less than 10 cm under the condition of III-grade surrounding rock and II-grade surrounding rock sections requiring inverted arch. (5) The recommended value of bedding thickness meeting the design service life is 20 cm under the condition of II-grade surrounding rock.

中文翻译：

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40吨轴重单轨压载重载铁路隧道隧道底结构设计参数与疲劳寿命研究

利用有限差分法建立了隧道与围岩的耦合计算模型，结合累积损伤机理，研究了单轨压载隧道40吨轴重，列车重载下衬砌结构的主要设计参数。隧道底部围岩的破坏及隧道底部混凝土结构的疲劳寿命特性 结果表明：（1）Ⅲ级以上断面应设置倒拱。是否根据II级岩性和地下水条件确定是否在II级以下的区域设置了反转器。当围岩条件良好且采用隧道底部结构（无倒置结构）时，建议厚度大于20cm，混凝土强度等级应不低于C35。（2）连接方式：倒拱与隧道侧壁应按顺序连接，以减小应力集中，改善倒拱与侧壁连接部位的应力状态。（3）建议单线隧道倒置的上升跨度比应为1/6〜1/8；当围岩条件较差时应取较大的值，而当围岩条件良好时应取较小的值。（4）倒拱的厚度在V级围岩条件下建议不小于20 cm，在IV级围岩条件下建议不小于15 cm，在IV级围岩条件下建议不小于10 cm III级围岩和II级围岩段需要倒拱的条件。