The corrosiveness of artificial soil may lead to the collapse of eco-engineering projects on rock slopes in mining areas

Abstract

Large-scale highways, railways and mining infrastructures have created a large amount of denuded steep rocky slopes, causing ecological and environmental problems. Artificial soil and metal mesh are the key components for eco-engineering on rocky slopes to restore slope ecosystems. However, artificial soil significantly differs from natural soil in composition and electrochemistry, which may accelerate the corrosion of metal mesh. In this study, three eco-engineering projects for rocky slope protection in an abandoned opencast quarry were chosen to conduct our experiments, in which ecological restoration measures have been conducted for 3 years, 6 years, and 10 years and corresponding soil samples of artificial soil and metal mesh were collected, and the electrochemical properties of artificial soil and the life span of metal mesh at different slope conditions were examined. The results showed that the electrochemistry of artificial soil was significantly different from that of natural soil since their soil compositions were extremely different. The corrosion of metal mesh at the lower slope position was the strongest and the soil corrosivity of artificial soil was stronger than that of natural soil. Moreover, artificial soil had low resistivity and a moderate degree of stray current, with the oxidation-reduction potential being oxidative. The results from PCA analysis further confirmed the above-mentioned results. The results in this study suggested that metal mesh rocky slopes should be closely monitored around the 10-year mark after its application, especially at the lower slope position, to prevent soil collapse and ecosystem degradation. Overall, our study has provided new insights into the eco-engineering of rocky slopes and implications on how to avoid environmental risks induced by metal mesh failures.