Study on the effect of calcareous cementation on sand dune of desert

Abstract

Within the Badain Jaran Desert located in western Inner Mongolia, China, megadunes cover 60% of the entire area of the desert. Sand dunes have an average height of 200-300m and up to 460m in the southeast. The mechanism of formation of the megadunes is still not fully understood. Some researches advise that the patterns of mega-dunes are controlled by underlying rocky humps whilst some papers relate it to the morphology of underlying structures which may have been formed by tectonic movements. The importance of the underlying calcareous layers was seldom discussed. However, with the presence of calcareous layers, the overall stability of the sand dune would be higher. The effect on the slope stability with the presence of calcareous soils was further investigated with slope model. The relations between the height of the sand dune and the calcareous layers were analyzed in this study. The observations are supported by various evidences such as microscopic analysis and statistics. From the data and graphs collected through the findings, it was observed that 8% was the minimum content of calcium carbonate for calcareous cementation to happen. The slope stability with and without calcareous layers were checked with computer model. It was observed that the slopes with the presence of calcareous layer gave higher factor of safety at the critical slip surface.