兰新高速铁路高寒地段路基温度场数值模拟分析

兰新高铁浩门至大梁区间所处地区海拔高,气温低,冻结期长,属于深季节性冻土区。为解决该区间路基冻害问题,依据当地气候条件,运用ANSYS有限元分析软件,对低路堤、零断面换填路基及不同深度处铺设保温材料的路基温度场进行数值模拟,分析路基冻结深度的变化规律和最大冻结深度,为高寒区高速铁路路基冻害防治措施设计提供参考。研究表明:(1)由于兰新高铁浩门至大梁区间海拔高、冬季冻结时间长、气温低等原因,导致路基冻结深度大;(2)零断面换填路基实测地温和数值模拟计算结果基本相符,所选计算模型、参数等可以为其他相同条件断面数值模拟分析采用;(3)铺设保温板路基温度场较未铺设保温板的0℃线上移,冻结深度增加速率变小,最大冻结深度明显减小,路基保温效果较好;(4)由于路基边坡、基床以下部位土层性质、厚度、热物理参数等影响,低路堤最大冻结深度比零断面换填路基大。

Numerical Simulation Analysis on Subgrade Temperature Field in Alpine and Cold Section of Lanzhou-Urumqi High-speed Railway

Haomen-Daliang section of Lanzhou-Urumqi high-speed railway is high in altitude, low in temperature and long in freezing period in winter, belonging to seasonal frozen region with deep frost depth. In order to solve the problem of subgrade freezing damage in this area, temperature fields of subgrade with low embankment, zero-height subgrade and thermal insulation material at different depths are simulated with ANSYS finite element analysis software according to the local climate conditions. The variation rules of subgrade freezing depth and the maximum freezing depth are analyzed so as to provide references for the design of prevention and control measures against the frost damage of the subgrade of high-speed railway in the alpine and cold region. Research results show that:(1) The frozen depth of subgrade is caused mainly by the high altitude, long freezing time and low temperature.(2) The subgrade temperature field measurements are basically consistent with the numerical simulations, so the selected calculation model and parameters can be used for numerical simulation and analysis of other sections under the same condition.(3) Zero centigrade line in the temperature field of subgrade with thermal insulation board moves up, the increase rate of frozen depth is getting smaller, the maximum freezing depth decreases obviously, and the heat preservation effect of the subgrade is good.(4) Owing to the influence of embankment slope, soil property, thickness and thermal physics parameters below the roadbed, the maximum freezing depth of low embankment is larger than that of zero-height section.