Theoretical analysis of the critical impact velocity of aeolian saltating grains to rupture microbiotic crusts
关于跃移沙破坏生物结皮时的临界速度的理论分析

The rupture of a microbiotic crust under the impact of a single saltating grain was theoretically studied using the classical theories of elastic thin plate and plastic mechanics. A quantitative relation between the critical impact velocity of saltating grain and the characteristics of microbiotic crust was obtained. The effects of microorganisms were taken into account through the values of Young's modulus, Possion ratio and the yield stress of microbiotic crust, which are mainly determined by component species, numbers, and development stages etc. The current study indicates that a rigid and weak microbiotic crust is more easily broken down by saltating grains than a soft and strong one. The formula we obtained will be helpful to evaluate the relationship between the microbiotic crust and the motions of wind-driven grains.