青藏高速公路路基降温措施有效性模拟分析

为了评价已有的冻土路基工程技术对青藏高原多年冻土区高等级公路宽幅路基的适用性,运用ABAQUS有限元软件及其二次开发平台,建立了多年冻土地区宽幅路基温度场有限元分析模型,并运用该模型对普通路基、碎石路基、EPS隔热层路基以及隔热层-碎石复合路基温度场进行对比分析,对4种宽幅路基融深变化规律进行研究.结果表明,不同降温措施条件下路基温度随时间均呈周期变化,但每年平均温度总体上升,且相同的时间和路基宽度条件下,隔热层-碎石复合路基温度最低、热稳定性最好;普通路基第十年最大融深随路基宽度的增加呈直线上升趋势,碎石路基融深随宽度的增加呈三阶段增长趋势,EPS隔热层路基融深随宽度的增加呈两阶段增长趋势,复合路基融深随着宽度的增加逐渐增加但变化不大;单一的EPS隔热层措施、碎石路基对于多年冻土区宽幅路基降温效果较差,隔热层-碎石复合路基降温效果最优.

Simulation Analysis on Cooling Effectiveness of Engineer Measures for Subgrade of Qinghai-Tibet Expressway

In order to evaluate the effectiveness of existing engineer measures for wide permafrost subgrade in Qinghai-Tibet plateau, a finite element (FE) model of temperature field of permafrost subgrade was first constructed by FE software ABAQUS and the secondary development platform. The temperature fields of normal subgrade, rock embankment, EPS insulation layer subgrade, and composite subgrade were then analyzed and compared with the help of the FE model. Furthermore, the change rules of melting depth for four kinds of subgrades were studied. The results demonstrate that the temperatures of the subgrades with different cooling engineer measures all change periodically over time, but the mean annual temperature rises. Under the same condition, the temperature of composite subgrade is the lowest, and its thermal stability is the best. When the width increases, the melting depth of normal subgrade rises linearly, and the melting depth of rock embankment shows a three-stage rising trend, while for EPS insulation layer subgrade it is a two-stage rising trend. Meanwhile, the melting depth of composite subgrade rises with the increase of the width, but the variation is very small. The mere EPS insulation layer or rock embankment is ineffective, while the insulation-gravel composite subgrade has excellent performances on the cooling effectiveness of wide subgrade in permafrost region.