土体剖面温度物理模型试验研究

PHYSICAL MODEL TESTING OF TEMPORAL VARIATION OF SOIL TEMPERATUE IN DEPTH

利用自主开发的土体温度物理模型试验系统,研究了土体剖面温度随时间的变化规律,通过改变土体表面的覆盖层属性,对比分析了裸土和混凝土板覆盖下土体剖面的热传递特点。结果表明:在恒定热源作用下,土体剖面温度迅速上升到一定值之后逐渐趋于稳定,初始升温速率随深度的增加而呈指数递减,最终平衡温度随深度的增加而显著衰减;温度在土体剖面上的传递存在明显的滞后效应;混凝土板覆盖下土体的初始升温速率和最终平衡温度较裸土高;土体剖面热通量反映了土体中热量的传递特征,其变化规律与上下土层间的温度差变化规律一致。

A physical model experimental system is developed in order to investigate the temperature variation with time in soil depth profile.The thermal conduction characteristics in soil profile with different surface covers but under the same heat source are compared and analyzed.The obtained results show that（a）the soil temperature increases quickly at the beginning stage and then tends to a relative stable value;（b）with increasing depth,the initial temperature increase rate of soil decreases exponentially;and（c）the final equilibrium temperature of soil also decreases with increasing depth.It is observed that the damping and retarding effects of soil temperature with depth are obvious.By comparing with bare soil,the initial temperature increase rate and final equilibrium temperature of soil with surface concrete plate cover are higher.The thermal flux in soil profile,which is measured by thermal flux plate,reflects the thermal conduction characteristics in time,and directly depends on the variation of temperature gradient between soil layers.