碎石层的“热半导体”作用

On the "Thermal Diode" Function of Crushed Rock Layer

碎石层在冰缘地区有广泛分布.众多文献报道,碎石层具有降低其下地温的作用,根据这些现象,对其致冷形成机理进行了研究.结果表明:对封闭的倾斜碎石层,其致冷机制主要基于Rayleigh-Bènard对流;对开放的倾斜碎石层,其致冷机制包括“烟囱效应”和风引起的强迫对流.并进一步用模型试验、数值模拟和现场的实体试验对致冷机理进行了验证.碎石层己在青藏铁路建设中得到广泛应用,并被证明起到了冷却路基的作用.这一措施效果显著、施工简便、环境友好且成本相对较低,可用于多种冻土工程,以适应全球变暖的影响.

Crushed rock layers are distributed widely in periglacial environment. Numerous reports indicated that the crushed rock has the function of decreasing ground temperature underneath. This article suggests that for the closed inclined crushed rock the cooling mechanism is mainly based on the Rayleigh-Benard convection, and for the open inclined crushed rock the cooling mechanisms include chimney effect and forced convection caused by wind. A model experiment, a numerical simulation and an in-situ embankment experiment have been conducted to demonstrate the above hypotheses. The crushed rock layers have been comprehensively used in the construction of the Qinghai-Tibet Railway. It has been proved that this new method is effective for cooling the roadbed, with the characteristics of environmental friend, relative cost-efficient and easy to use. It can be applied to various permafrost engineering projects facing global warming.