列车振动荷载对柴达木盆地雅丹地貌稳定性的影响

基于青海省地方铁路鱼卡至一里坪线路经过的雅丹地貌密集分布区现场调查和地质勘探,以室内物理力学试验结果为基础,利用数值软件ABAQUS对区域内典型雅丹模型进行稳定性计算分析。选取典型形态的雅丹地貌进行天然状态下的静力分析,对该区内雅丹地貌的天然稳定性做出评价。进而根据列车通过场地振动测试结果,对列车振动荷载作用下不同边坡角度雅丹的动力响应特征进行了计算,揭示了列车振动引起的雅丹失稳破坏机制。研究结果表明:天然状态下不同施工边坡角度对雅丹地貌自身的稳定性影响很小,可以忽略不计;列车荷载振动作用下对雅丹地貌自身的稳定性影响显著增强,其总位移、Mises应力值和剪应力S12值均显著增大,且随着列车运行距离的增大,雅丹的峰值加速度急剧减小。随着边坡角度的增大,加速度的放大作用愈加明显,且坡脚到坡顶的PGA呈明显放大趋势。最后给出了该线路在列车振动荷载作用下对其周围雅丹地貌稳定性影响显著的距离和合理的路基边坡角度范围。

The Influence of Train Vibration Loads on Stability of Yardang Landform in Qaidam Basin

Site investigation and geological exploration of Yardang landform intensive area are carried out, where local railway of Yuqia to Yiliping in Qinghai Province passes through. Based on physical and mechanical test results, a stability analysis of typical Yardang landform is performed by using ABAQUS, and itsnatural stability is evaluated by a static analysis. According to the results of the train vibration test, dynamic response characteristics, with different slope angle models, are calculated to reveal the failure mechanism of Yardand landform due to train vibration. The research results show that the effect of slope angle is very small for the stability of Yardang landform in natural state. Under train vibration loading, the total displacement and stresses of the slope model are significantly increased; with the increase of the train running distance, the peak acceleration of the Yardang model decreases sharply. As slope angle increases, the acceleration of the slope model is gradually amplified from slope bottom to top. At last, the distance range which has significant influences on the stability of Yardang landform around the line under train vibration loading is put forward, and reasonable slope angle of roadbed is also given.