Based on the typical tunnel structure of Menghua railway which is still under construction,a numerical study was performed,mainly focusing on the dynamic response,fatigue life and strengthening measures of loess heavy haul rail-way tunnel.The results show that:with an increase of axle load and railway freight transport volume,the existing railway tunnel cannot meet the long-term safety requirement without strengthening measures.The adaptability of loess heavy haul railway tunnel cannot be improved effectively by using sole systematic bolt,system anchoring bolt combined with ground treatment should be adopted (the length should reach to 4 m or more).Then the safety operation requirement of the heavy haul train can be satisfied.The research indicates that the centre of secondary lining of inverted arch,and sidewall and inverted arch joint of initial support are the most unfavorable load positions of the tunnel's bottom structures under the ac-tion of 30 t axle heavy haul train.In order to satisfy the 100 a safety design service life of tunnel structures under the op-eration of 30 t axle heavy haul train,the upper-limit fatigue strength of initial and secondary lining of new loess tunnel were deduced,which are 1.30 MPa and 1.62 MPa,respectively.The results can provide reference for present design of heavy haul tunnel structures.%以在建的蒙华铁路典型隧道结构型式为基础,针对新黄土区重载铁路隧道结构动力响应、疲劳寿命以及合理强化措施等问题,采用数值模拟的方法进行研究.结果表明:随着轴重和运量的增加,既有铁路隧道无法满足30 t轴重列车长期安全运营的要求,应采取强化措施.而单一的系统锚杆注浆加固强化能力有限,须采用系统锚杆与隧底地基加固(加固深度4 m及其以上)的联合强化措施方能满足其疲劳寿命要求.通过研究,指出30 t轴重列车荷载作用下隧底结构疲劳易损位置,即二次衬砌仰拱中心、初期支护仰拱与边墙连接处,并得到满足100 a设计使用年限,新黄土区隧道二次衬砌、初期支护混凝土结构在轴重30 t列车荷载作用下的疲劳上限强度,分别为1.30和1.62 MPa,可为设计参考.
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