青藏铁路多年冻土区路基结构的动力分析

Dynamic Analysis of Subgrade Structure of Qinghai-Tibet Railway in Permafrost Region

研究目的:本文对青藏铁路冻土路基在列车荷载下的结构动力进行了分析研究,为多年冻土区路基工程设计和铁路运营安全分析提供了依据。研究方法:以青藏铁路清水河多年冻土区试验段路基结构为工程背景,利用列车——轨道二维动力模型得到的道床底部列车荷载激励曲线,对冻土路基结构进行有限元时程反应分析,探讨冻融状态下路基的列车振动荷载效应。研究结论:无论是暖季融化还是寒季冻结状态,列车振动荷载产生的土体压应力都大大高于静荷载,车速对土体动应力反应有明显影响;冻结状态下,路基中下部土体的动力反应较大,而暖季融化时路基顶部土体对动应力有较显著的放大作用,因此,在工程设计和运营养护时应有针对性地对结构进行加强。

Research purposes： The analysis and research were done on the structural dynamics of the subgrade of Qinghai - Tibet Railway in permafrost region under the load of train for the purpose of providing the basis for design of subgrade in permafrost region and making analysis of railway operation. Research methods：Taking the subgrade structure in test section of Qinghai - Tibet Railway in Qingshuihe permafrost region as object, the finite element time - histories reactive analysis was done by using the excited curves of roadbed bottom under train load obtained from two dimensional dynamic model, and the exploration was made on the subgrade effects to the train vibration load under freeze -thawing condition. Research conclusions：No matter whether under the thawing condition in warm season or under freezing condition in cold season, the pressure stress of soil body caused by train vibration load is much higher than that under static load and the stress of soil body influences the train speed obviously. Under freezing condition, the soil body in middle and bottom parts of subgrade has a larger dynamic effect, but under thawing condition in warm season, the soil body on the subgrade has obvious amplification effect to dynamic stress. Therefore, the structure should be reinforced correspondently in engineering design and maintenance.