多年冻土区跑道水热力耦合地基温度应力分析

Hydro-thermal-mechanical coupling analysis of temperature stress on runway subgrade in permafrost regions

为了揭示多场耦合作用下多年冻土宽幅跑道温度应力的分布规律,首先,采用室内试验模拟了东北某地区冷季降温时多年冻土地温的变化过程,并与基于水热耦合理论建立的温度场模型进行对比;其次,依据东北地区多年冻土地质条件,并结合跑道结构力学参数随温度变化规律建立跑道水热力耦合的地基二维有限元模型;最后,分别计算了30年内1月、4月、7月和10月跑道道面结构和地基整体温度应力的分布规律。结果表明,基于水热耦合的有限元模拟计算冻土温度场的方法是有效的;跑道中间的水平温度应力影响深度约为5 m,一年中1月和7月温度应力变化较为显著,冻土地基大范围内以温度压应力为主,且逐年增大;道面结构层内的最大温度拉应力在1月出现在跑道中心面层,约占面层材料劈裂强度的30%,在7月出现在跑道基层,约占基层材料劈裂强度的28%,因而多年冻土区跑道地基温度应力在夏季和冬季需要引起重视。上述成果可为在多年冻土环境开展机场跑道设计提供参考。

In order to reveal the distribution law of the temperature stress of the permafrost wide runway under the coupling effect of multifield,the temperature change process of the permafrost during a cold season in a certain region of Northeast China was simulated via indoor experiment and compared with the temperature field model based on the hydro-thermal coupling theory.Furthermore,according to the geological conditions of permafrost in Northeast China,combined with the change of the mechanics parameters of runway structure with temperature,a hydro-thermal-mechanical coupled two-dimensional finite element model of runway foundation was established.Finally,the distribution law of the overall temperature stress of the runway surface structure and the foundation in January,April,July and October during the 30 years was calculated.The results show that the method of calculating the temperature field of frozen soil based on the finite element simulation of hydro-thermal coupling is effective.The influence depth of horizontal temperature stress in the middle of the runway is about 5 m.The temperature stress changes significantly in January and July during the year,and temperature compressive stress exists in most of the permafrost foundation,and it increases year by year.The maximum temperature tensile stress in the pavement structure layer appeared in the center surface of the runway in January,which was about 30%of the split strength of the surface material,and appeared in the base of the runway in July,which was about 28%of the split strength of the base material.It can be seen that temperature stress of permafrost runway foundation need attention in summer and winter.The above results can provide reference for airport runway design in permafrost environment.