Influences of ecobar spacing distance on flow and sand reduction of iron tailings slopes

Iron tailings ponds have been confined to large emissions and low utilization rates in recent years. A large area of exposed surface and slope can be found in the rest of the iron tailings ponds, leading to soil erosion and slope landslides. This study aims to clarify the erosion control mechanism of ecological bar barriers in slope ecological restoration. The slopes of the tailing pond were taken from the Zhangxuan Iron Mining District, Hebei Province, China. Artificial rainfall simulation was adopted to evaluate the flow and sand reduction of ecological bar barriers at different intervals. The test parameters were set as the slopes of 25° and 30° with the ecological rod spacing of 0.40-1.00 m in the rainfall intensity of 30-90 mm/h. The results show that: 1) The initial production time of ecological rod blocking increased by 0.44%-57.76% and 1.08%-39.14%, respectively, at different intervals, compared with the bare slopes, indicating the decrease with the increase of the ecological rod intervals, slopes, and rainfall intensity; The flow was reduced by -2.79%-80.68%, and 12.67%-76.45% with the increase of rainfall intensity. The trend was enhanced at the rain intensity of 30 mm/h with the shortening of the ecological bar interval. There was no outstanding variation in the rain intensity of 60 and 90 mm/h; The runoff flow rates were reduced by 20.78%-55.12%, and 20.16%-41.57%, respectively, with the increase of slope. While the 0.67 m interval was performed the best in the flow rate reduction of the slope; 2) The sand reduction was -127.47%-71.57% and -287.19%-62.01%, respectively. Furthermore, the sand reduction effect was weaker than the flow; 3) The cumulative volume of runoff and erosion decreased with the shortening of the ecobar interval under the rainfall intensity of 30 mm/h. There were no outstanding changes under the rainfall intensities of 60 and 90 mm/h. The cumulative erosion volume of slope 30° was much larger than that of slope 25° under the rainfall intensity of 90 mm/h; 4) Pearson correlation analysis was implemented on the indicators of streamflow and sand production. The ecological rod blocking was dominated to reduce the streamflow and cut the flow velocity on the slope. The dominant influencing factors on streamflow and sand production were the rainfall intensity, followed by the slope; 5) The ecological rod spacing of 0.40 m was recommended for the slopes with 25° and 30°, and the rainfall intensities of 30 and 90 mm/h. At the same time, 1.00 m ecological rod spacing was suitable for 60 mm/h rainfall intensity. The finding can provide a strong reference to apply the ecobar blocking in the ecological restoration of iron tailing slopes.