The effect of wind pressure on surface erosion of soft rocks in arid regions

Abstract

The wind acts as a land-shaping agent in desert and coastal regions, with more significant effects on soft, porous rocks than on massive rock formations. Air-suspended particles degrade rock surfaces, form cavities, and produce drift channels; however, abrasions that have been formed without the impacts of suspended particles are occasionally observed on very soft rock surfaces in areas exposed directly to the wind. The effect of wind without abrasive particles on soft and porous rock samples was examined using a newly designed wind tunnel. Samples were exposed to various wind speeds of 6–9 m/s to determine the most efficient wind speed. Ignimbrite, mudstone and sandstone specimens, all of which possess high porosity and low strength, were tested in the wind tunnel under a constant air temperature for 1 year. During that time, changes in sample weight were measured at weekly intervals. The specimens started to decrease in weight after losing surface moisture, with the highest weight loss observed in the samples with high porosity and low strength. Air pressure from the wind caused tension on rock surfaces. Surface strain measurements were carried out to determine the effects of wind pressure on weight loss. The maximum strain (250 μ) was recorded on mudstone samples with high porosity and low strength. A good relationship was detected between surficial strain and weight loss. The air pressures on the sample surfaces caused by the wind forces were measured with a new sensor. The air pressure values measured on the surface oscillated between −56 and 133 Pa.