关于跃移沙破坏生物结皮时的临界速度的理论分析

利用经典的弹性薄板与塑性理论探讨了生物结皮在单颗跃移沙粒碰撞作用下的破坏问 题,建立了一个联结跃移沙粒的临界撞击速度和结皮性质的解析关系式. 种类、数量、发展 阶段等生物效应主要通过结皮的杨氏模量、Possion比、屈服应力等宏观参量引入. 结果表 明,刚度大、强度低的生物结皮更容易被跃移沙粒所破坏. 给出的关系式将有助于进一 步研究风沙运动和结皮之间的相互作用.

Theoretical analysis of the critical impact velocity of aeolian saltating grains to rupture microbiotic crusts

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.