Effective thermal conductivity of thermokarst lake ice in Beiluhe Basin, Qinghai-Tibet Plateau

Effective thermal conductivity (ETC) of thermokarst lake ice (TLI) is a key factor in simulating the ice processes in permafrost regions of Qinghai-Tibet Plateau (QTP). Typical TLI blocks sampled from central QTP were prepared to measure their ETC in vertical and horizontal directions at various temperatures. The ETC values of TLI are ranging between 1.60 and 2.10W/(mK). The ETC values in both directions are very close, and change obviously along the ice depth. The ETC of TLI increases monotonously with decreasing ice temperature between 0 and 25°C. Both the theoretical modeling and experimental results demonstrate the effects of gas pore structures on ETC of TLI. The temperature-averaged ETC decreases gradually as the porosity increases. A simple linear combination of two structural models is proposed for predicting the ETC against the porosity by introducing an empirical coefficient. This coefficient is controlled by the gas pore size, content, shape and configuration.