An analysis of soil detachment capacity under freeze-thaw conditions using the Taguchi method

Soil detachment is one of the most important processes of soil erosion, as it is of great significance for the prevention and treatment of soil erosion in areas subject to seasonal freeze-thaw. However, little research on soil detachment capacity (SDC) during the thawing period has been carried out and this process remains unclear. In order to elucidate the effects of slope, flow discharge and freeze-thaw factors on SDC, the indoor artificial freezing-thawing method was applied in combination with scour to simulate the soil detachment process. Signal-to-noise (S/N) ratio analysis was also used to evaluate the experimental results by applying the Taguchi method. The results showed that SDC increased with the increased of slope and flow discharge. As the number of freeze-thaw cycles and moisture increased, SDC initially decreased and then increased. A maximum soil detachment value was achieved at 12° slope and when moisture was 12%, flow discharge was 1.2 L/min, and there were ten freeze-thaw cycles. Statistical analysis with the help of Taguchi method showed that the percentage contribution of the different factors to SDC occurred in order, slope (76.02% at p = 0.002) > flow discharge (13.39% at p = 0.019) > soil moisture (6.92% at p = 0.047) > the number of freeze-thaw cycles (3.67% at p = 0.106), while factors related to hydrodynamic conditions exert a greater influence than those related to freeze-thaw. Finally, the Taguchi and orthogonal analysis methods showed the similar predictive results R2 = 0.98 and R2 = 0.97 respectively. However, the Taguchi method was more accurate than the orthogonal analysis methods due to less relative error 8.98% and 15.11% respectively. These results provided a scientific reference for the study of the mechanisms of soil erosion as well as for the applicability of the Taguchi method.