Partial Saturation and Seismicity on Steep Reclaimed Slopes

While traditional mine reclamation methods emphasize compaction to increase the strength of the materials and ensure stability of the restored slope, high compaction restricts the successful reforestation of reclaimed mine sites. The Forest Reclamation Approach (FRA), which uses low compaction in the uppermost 1.2–1.5 m of the surface has been shown to facilitate the establishment of healthy native forests. Stability analyses of three steep FRA slopes from the southern Appalachian region have shown that the long-term static stability is not compromised, and that the infinite slope method provides a rational method to evaluate the stability of steep FRA slopes. In this article, modifications of the infinite slope equation are utilized to (a) include the effects of matric suction due to unsaturated soil conditions and (b) evaluate the seismic performance of FRA slopes based on spectral accelerations. Monthly variation of the water content at three research sites demonstrated the seasonal stability variation of FRA slopes due to matric suction, while seismic analyses illustrated the conditions under which instability may occur.