The characteristic of aeolian environment and its impact on engineering construction in The Gurbantonggut Desert, China

摘要

The Gurbantonggut Desert, located at the center of Junggar Basin, has an area of 48,800km~2, which is the biggest stable and semi-stable desert in China. There are abundant oil and natural gas resources in the underground of the desert. With the oil-gas resource exploitation more and more engineering projects have been built in the center of the desert, such as the desert highways, the oil fields and so on. However, aeolian environment in The Gurbantonggut Desert has a great impact on the engineering building and engineering safety. There are more than 20 gale days per year in the center of the desert, and the main directions for the effectively blown sand wind are NE and NW, and sometimes the strong SE winds occur in the east part of the desert. The effectively blown sand winds mainly appear between April and September, which counts 80% of windy times in the whole year. It is obvious that the huge transport potential formed by the strong wind force badly endangers the engineering construction. Primary shapes of sand dunes in the desert are longitudinal and dendritic dunes, which occupy 80% of total area of the stable and semi-stable desert. The sand particles of the desert are coarser, and the average grain size is 0.2～0.22mm and 0.15～0.17mm in the southern and the northern part of the desert respectively. The vegetation coverage is 15～50% and the microbial crust covers about 85% of the desert surface. In this case, most dunes are stable or semi-stable, only on the top of the dunes existing about 30m mobile or semi-mobile sand belts. That indicates that the fixed or semi-fixed sand surfaces are dominant in desert, which prevents blown sand from doing harm to the engineering construction. Meanwhile, with the engineering construction, the fixed or semi-fixed sand surfaces are easy to be destroyed in the desert, which threatens the engineering construction and safety greatly, In general, there are about 1m thick moist sand layers in the desert and the moisture content has great changes in time and space. The moist sand layer in the desert plays an important role on the ecological rehabilitation and the aeolian disaster control in engineering disturbance areas.