Steep slopes, characterized by their high gradient and limited soil and water resources, pose significant challenges to plant colonization. Consequently, the ecological restoration of steep slopes is one of the major challenges in the field of mine site rehabilitation. This study evaluated the impact of slope conditions on the restoration effectiveness during the early stages of ecological restoration. Two ecological restoration slopes with different slope conditions, excavated slope and filled slope, were selected, and restored by hanging net and soil spraying measures. The unrepaired slope was used as the control. The results showed that ecological restoration has a significant effect for soil and water conservation; runoff and sediment were reduced by 61.38% and 99.28%, respectively, and infiltration increased by 104.26%, compared to untreated slopes. Furthermore, ecological restoration could effectively reduce runoff erosion dynamics and soil erodibility, and alter the runoff–sediment relationship on slopes, thereby substantially influencing the yield processes of runoff and sediment of the slopes. Notably, the reduction effect of ecological restoration measures on runoff and sediment was more significant on excavated slopes than on filled slopes. The runoff and sediment yield of excavated slopes were 19.06% and 53.77% lower than that of filled slopes, respectively. From a soil and water conservation perspective, the ecological restoration measures of hanging net and soil spraying were more suitable for application to steep excavated rock slopes. However, further research is needed to evaluate its applicability to filled slopes.

Freeze‐thaw interface in unsaturated coarse‐grained soil (CGS) is a weak plane which can cause slope failures in cold regions. This study presents a series of large‐scale direct shear tests on freeze‐thaw interface in CGS through a temperature control system. The tested soil was taken from a high slope in the Qinghai‐Tibet Plateau. It was remolded with three dry densities (1.9, 2.0, and 2.15 g/cm³) and three moisture contents (9.0%, 11.5%, and 14.0%). With testing results, direct shear curves mainly performed as hardening deformation, and they were affected considerably by specimen conditions. The shear strength increased with both the increasing dry density and normal stress, but it was opposite with moisture content changed. The cohesion and internal friction angle increased with the increase in dry density but decreased with the moisture content. The particle movement and water migration of freeze‐thaw interface in CGS during the test were significant, and they had close relations with the shear properties of specimens. And, an empirical model was produced to express the effect of pore ice on the shear strength of interface during the shear test. The tests and analysis in this study may provide useful references for CGS slope stability analysis in high cold regions.

The research on the key factors of surface subsidence in paste backfilling mining of thick coal seam in deep mine is a complex system engineering, which involves mining, backfilling, support, subsidence, safety, and other aspects. At present, there is no systematic research on the key factors of surface subsidence in paste backfilling mining of thick coal seam more than 6 meters in a deep mine. In this paper, field research, laboratory experiments, theoretical analysis, and other research methods are used to carry out the research about 3# coal seam under buildings in the Lu’an area. The main conclusions are as follows: through the construction of the fuzzy extension model of surface subsidence in paste backfilling mining, five types of surface subsidence are obtained, including overburden structure, roof subsidence before backfilling, nonbackfilling account, the strength of filling body, and backfilling technology. It is the key factor to control the surface subsidence; the optimization measures are given to provide a reference for the reasonable design of paste backfilling mining in other working faces. The research conclusion has a certain reference value for solving a series of problems such as coal resources under buildings, solid waste disposal, controlling strata and surface movement, improving the recovery rate of mine resources, and extending the service life of mine.

In rock slopes with a three-section landslide, the locking section is the key control factor. This study conducted double-sided freeze–thaw tests on a scale model of a rock slope with a three-section landslide in a cold region. We monitored the changes in frost heave force, strain, and fracture during the water–ice phase change and investigated the effect of the trailing edge tensile crack length on the frost heave fracture of the locking section. A crack frost heave model was proposed based on rock and fracture mechanics to explore the mechanism of slope crack freeze–thaw weathering. According to the results, the slope shoulder froze first, with the freezing front progressing from the slope shoulder to the interior of the rock mass. The fracture failure in the three-section rock slopes was mostly caused by the frost heave of the trailing-edge tensile cracks. The largest frost heave force and locking section deformation occurred when the temperature of the top of the trailing edge tensile crack decreased from −3.5 °C to −6 °C (whereas that of the bottom of the crack dropped from 0 °C to −2.6 °C). Additionally, the results demonstrate that the frost heave force is positively correlated with the length of the trailing edge tension crack, and shear marks are virtually absent on the tensile fracture surface.