Study on Stability Analysis of Soil-Rock-Mixture Slopes under Freeze-Thaw Erosion in Greater Khingan Mountains

Abstract

Abstract Under the action of freeze-thaw erosion, slopes in permafrost regions frequently suffer from geological disasters. The unique properties of soil-rock-mixture slopes further complicate this freeze-thaw stability problem. To study the effects of freeze-thaw erosion on the stability of soil-rock-mixture slopes, several indoor tests were first carried out on the specimens collected from the target bare slope at the K105+750~K105+850 section of the Ali River to the Kubuchun Forest Farm along National Highway 332 in permafrost regions of Greater Khingan Mountains, and then, according to the test results, damage theory, strength reduction method, Python script, and ABAQUS numerical analysis software, the slippage and safety factor of the bare slope under freeze-thaw cycles were obtained, and finally, the damage degree of freeze-thaw erosion to the bare slope was quantified. To improve the stability of bare slope in the freeze-thaw environment, the composite ecological slope protection measures of arched skeleton + three-dimensional net + grass planting were finally selected, and its feasibility is verified with the help of on-site monitoring and numerical simulation; then, the long-term freeze-thaw stability of the slope after revetment was studied. Key findings indicated that (1) the threshold between soil and rock in the target slope was 5 mm, the soil-to-rock mass and volume ratios of the slope were 55.04% : 44.96% and 69.38% : 30.62%, respectively. (2) After the 150 freeze-thaw cycles, the peak strength and elastic modulus of the specimens decreased 59.7% and 79.50%, respectively. (3) Meanwhile, the freeze-thaw damage was 0.79. (4) The slope safety factor was inversely proportional to the number of freeze-thaw cycles. The target bare slope was unstable after 150 freeze-thaw cycles, and the safety stability reduction rate was 41%. (5) Compared with the bare slope, the shallow horizontal slip of the slope after revetment decreased from 1.528 m to 4.971 cm, and the slope safety factor increased from 0.997 to 4.501, which shows that the slope protection measures are initially feasible. In addition, the numerical analysis results are consistent with the field monitoring data, and the error between the two is ≤2.01%, which proves the rationality of the numerical model established in this paper and provides data support for subsequent research.