热棒路基降温效应的数值模拟

基于青藏公路冻土路基病害整治热棒试验工程，建立热棒路基的等效传热模型，运用有限元方法对其进行数值模拟，研究青藏公路环境条件下热棒的工作周期、工作状态与作用半径，并通过对试验工程2a观测数据分析，对比研究热棒在冻土路基中的降温效应。研究发现，热棒在约为5个月的工作周期内并非连续工作而呈波动式，实际工作时间为工作周期的2／3；热棒路基冬季降温效果明显，有利于路基土体冷储量增加，提高路基热稳定性；热棒在路基中的降温强度，水平方向随距离增大而衰减，有效作用半径为2．25m，深度方向在热棒蒸发段最大，降低上限附近季节融化层冻土热融敏感性。结果表明，青藏公路热棒试验工程中其间距采用4．0m是合理的，路基双侧设置热棒优于单侧，热棒向路基中心斜置更好。

Numerical simulation of cooling effect for heat pipe subgrade

Based on heat pipe test engineering for the frozen soil subgrade distresses treatment of Qinghai-Tibet highway, the equivalent model of heat transmission for heat pipe subgrade was established and simulated using finite element method, the working cycle, operating condition and operating radius of heat pipe were discussed under Qinghai-Tibet highway environmental conditions, the cooling effect of heat pipe in permafrost subgrade was compared with the two-year observation data of the subgrade. Comparison results show that heat pipe work is not continuous but fluctuant in one work cycle about five months, its actual working time is two-thirds of one work cycle, the cooling effect of heat pipe subgrade in winter is obvious, which is good for the contained cool increase of soil body and improves subgrade heat stabilization, there is a decrease for its cooling strength with the increase of horizontal distance, its effective operating radius is 2.25 m, its maximum cooling strength is in evaporation segment in depth direction, which low the thaw sensitivity of permafrost in the seasonal thaw layer about permafrost table. The results indicate that the space between heat pipes for 4.0 m is reasonable, the installation positions of heat pipes at two sides are better than at one side, pile oblique placement is better than perpendicular placement. 4 tabs, 8 figs, 15 refs.