列车荷载作用下隧道铺底结构疲劳寿命分析

针对我国既有铁路隧道铺底结构破损严重的现状,在试验研究和数值计算确定隧道铺底结构疲劳危险部位的基础上,采用动力有限元方法计算得到列车动载作用下隧道铺底结构疲劳危险部位的弯拉应力时程曲线,而后根据疲劳累积损伤理论,采用Tepfers的混凝土单对数疲劳方程求出隧道铺底混凝土结构的使用寿命及其损伤度。计算中考虑了10 cm2、0 cm3、0 cm厚素混凝土和20 cm厚钢筋混凝土4种不同的隧道铺底工况,计算结果同模型试验结果的变化规律一致。根据计算结果得出20 cm厚钢筋混凝土铺底结构使用寿命较长的结论。

Study on the Fatigue Life of the Tunnel Bed Structure under Train Loads

In view of the severe situations on the bed diseases in the existing railway tunnels,the fatigue life of the tunnel bed is studied in this paper.On the basis of determining the fatigue positions of the tunnel bed by experimental study and numerical calculation,the tension-stress time-history curve for fatigue positions of the tunnel bed under train dynamic action is obtained with the dynamic finite-element method.Then according to the cumulative fatigue damage theory,the fatigue life and damage degree of the tunnel bed are derived by use of the Tepfers concrete single logarithm fatigue equation.The 10 cm-thick,20 cm-thick and 30 cm-thick plain concrete and 20 cm-thick reinforced concrete are taken into account in calculation.The change rule of the calculated results agrees with the model test results.A conclusion is drawn that the tunnel bed construction made of 20 cm-thick reinforced concrete offers comparatively long fatigue lives.