干旱区生态环境知识资源中心

In the northwest of China, loess is widely distributed, and the climate is mainly arid and semiarid. The use of loess as an alternative earthen final cover material is promising. However, the understanding on the performance of a compacted loess final cover is far from adequate. This paper will focus on the research on moisture and gas flow properties of loess as a cover material. Firstly, the distribution of loess and the climate condition in northwest China are reviewed. Then the multi-scale study program, including soil element tests, soil column tests and a full-scale testing facility at Xi'an landfill, is presented. The current findings from the laboratory and field study on the moisture and gas flow properties of the compacted loess are discussed with an emphasis on the scale effect. At last, the paper presents a preliminary numerical evaluation of the loess cover performance with respect to limiting water percolation and gas emission. The study demonstrates that the compacted loess final cover underlain by a gravel layer, having a considerable water storage capacity and relatively low conductivity for water and gas flow, is likely to perform well in the northwest China.