不同砾石盖度戈壁床面动力学特征研究

利用野外车载移动式风洞，对莫高窟顶不同砾石盖度戈壁床面的动力学特征进行了实地模拟实验。结果表明：砾石盖度直接决定戈壁床面的粗糙元数量和分布状况，进而影响近地表风速廓线、摩阻速度、床面粗糙度和剪切力；随着风洞进口指示风速的增加，摩阻速度呈线性递增，而动力学粗糙度在波动中呈下降趋势；相同高度，随着砾石盖度的增加，近地表风速逐渐降低，而摩阻速度、动力学粗糙度和剪切力呈线性增加；当床面盖度增加至35%时，动力学粗糙度达到0.30 cm，摩阻速度相应提高到0.93 cm/s，床面剪切力增加至1.11 N/cm。

Study on Dynamic Properties of Gobi Surface with Different Gravel Coverage

In order to understand the dynamic properties of Gobi surface, some wind tunnel experiments were conducted on the Gobi surface with different gravel coverage on the top of the Mogao Grottoes in Dunhuang, Gansu Province, China. The study results showed that gravel coverage of Gobi surface affected directly the amount and distribution of roughness elements, such as the wind speed profile, friction velocity, roughness degree and shear stress. Friction velocity was increased in a linear way with the increase of wind speed in the wind tunnel, but the dynamic roughness was decreased in a fluctuation way. Wind speed near Gobi surface was gradually decreased with the increase of gravel coverage, but the friction velocity, dynamic roughness and shear stress were increased in a linear way. When the gravel coverage was increased to 35%, the dynamic roughness, friction velocity and shear stress on the Gobi surface were 0.30 cm, 0.93 cm/s and 1.11 N/cm respectively. The results in this paper can be used to guide the design of sand control structures both in our study area and other Gobi regions where it suffers from windblown sand.