Shear stress caused by artificial raindrop impact at the soil surface

The purpose of this research is to develop methods of determination of the stress-strain state of the soil due to the drop impact of the artificial rain to increase the accuracy and simplify the research of drop and rain erosion, field and laboratory testing of sprinkler equipment. The calculation of the shear stresses arising at the point of impact drops of art ificial rain on soil, the role of these stresses in the mechanism for the development of drop and rain erosion, the expediency this value for testing irrigation equipment. For impacts of drop with a diameter of 1.73 mm on the basis of the magnitude of the shear stress was 158.44 ± 7.32 kPa (significance level p < 0.001) to 281.76 ± 11.18 kPa (p < 0.001) in the fall drops with a height from 1.0 до 2.5 m, respectively. For the case of hitting the ground drops with a diameter of 2.73 mm shear stress was 196.51 ± 5.72 kPa (p < 0.001) to 339.71 ± 33.35 kPa (p < 0.001) in the fall drops with a height from 1.0 to 2.5 m, respectively. The values of shear stress τ significantly correlated with the values of the drop height h (for drops with a diameter dd = 1.73 mm correlation coefficient r = 0.963 ± 0.029, p < 0.001; for dd = 2.73 mm r = 0.977 ± 0.014, p < 0.001). The median time of impact of drop 1.73 mm by soil was (5.95 ± 0.57) ∙ 10–5 sec., for the drop with a diameter 2.73 mm the time was (6.53 ± 0.67) ∙ 10–5 sec. Weber numbers We for the drop with the diameter of 1.73 mm were 459...1156, for the drop with the diameter of 2.73 mm – 728...1829.