动荷载作用下高温冻土路基动力响应的模拟试验研究

Simulation Experiment of Dynamic Responses of High Temperature Frozen Subgrade to Dynamic Loading

高温冻土地区铁路路基,由于列车动荷载对土体产生扰动而影响其稳定性。通过分析影响冻土路基应力、变形及温度场等主要因素,建立冻土路基模拟试验装置;在路基内部及周围地表布设压力和变形传感器,并用自行设计列车动荷载加载装置对路基施加模拟荷载,进行冻土路基动力响应模拟试验。试验获得不同动荷载频率作用下路基周围地表变形以及内部土压力的变化规律。试验结果表明:动荷载频率对地表竖向位移及路基土压力的影响均存在一个临界值,采用适当的列车行驶速度可减小对冻土路基的挠动;路基内部温度场监测结果表明,动荷载可引起土体局部温升,建议采用积极的防护措施以保护路基的冻结状态。研究成果可为维护青藏铁路路基稳定提供参考。

Dynamic loads of the train disturb the stability of the soil body of the railway subgrade in high-temperature permafrost regions.The test set for simulation of the frozen-soil subgrade was designed by analysis of the main influencing factors such as the inner soil pressures,displacements and temperature field of the subgrade.Using the self-made experimental loading device to apply dynamic loads onto the subgrade and placing pressure and deformation sensors inside the subgrade and on the surface of the surrounding ground,the dynamic responses of the frozen-soil subgrade were simulated.The changing law of deformation of the surface of the surrounding ground and pressure inside the subgrade under different frequencies of dynamic loading was found.The test results show there exists a critical frequency that influences the vertical displacements of the ground surface around the subgrade and the soil pressure of the subgrade,therefore,an appropriate train speed may reduce disturbances to the frozen subgrade.The results of monitoring the temperature field in the subgrade show that dynamic loads may cause an unneglectable load temperature rise in the soil body of the subgrade,so active measures are suggested to be taken to protect the frost state of the subgrade.Reference is provided for maintenance of the stability of the frozen subgrade of the Qinghai-Tibet Railway.