The 'thermal semi-conductor' effect of crushed rocks

Coarse rock layers are widespread in periglacial environments and can lower the temperature of underlying ground. We show that the cooling effect of closed and sloping rock layers is in the form of Rayleigh-Benard convection, while that of open and inclined rock layers is via the 'chimney effect' and wind-forced convection. Cooling has been observed in numerical simulations, laboratory models and field mock-up experiments. Coarse rocks were widely used in the construction of the Qinghai-Xizang Railroad and temperature monitoring of their performance indicates that they do have a cooling effect on embankments. The advantages of utilising such materials are many, including high efficiency, ease of installation, environmental friendliness and relatively low cost. It is recommended that they be used in engineering projects in sensitive permafrost areas as a cooling agent and/or a countermeasure against possible global warming. Copyright (C) 2007 John Wiley & Sons, Ltd.