Comparative tests on failure mechanisms of slopes with different geotechnical strengths in open-pit mines

In open-pit mining projects, the geotechnical conditions of stope slopes are complex, and the stability and failure modes of slopes with different geotechnical strengths are different, making daily maintenance of open-pit mines more difficult. However, there are few and immature research results on the geotechnical strength of open-pit mine slopes, especially there is a lack of relevant research on the failure mechanisms of slopes with different geotechnical strengths in open-pit mines. To this end, the bottom friction test method is used to analyze the deformation and failure process of open-pit mine slopes under different rock and soil strength conditions. Based on the measuring point image tracking technology and unit strain analysis program, the slope displacement and strain characteristics were obtained respectively, and the stability and failure mechanism of the slope under different geotechnical strength conditions were studied. The results show: ① As the rock and soil strength parameters increase, the failure mode of the slope gradually changes from shallow failure to deep failure. Its upper edge gradually moves away from the top of the slope, and the volume of the landslide gradually increases. ② The slope deformation can be divided into three stages: the first stage is the uniform deformation stage, and the displacement of the measuring points is small; the second stage is the local deformation stage, the displacement of some measuring points accelerates and increases, and the internal slip surface of the model gradually forms; the third stage is the local deformation stage. The stage is the destruction stage, and the displacement of the measuring points crosses and continues to increase. ③ There are differences in the strain characteristics and effect index in the upper, middle and lower parts of the slip surface of slopes with different rock and soil strengths. The deformation and failure modes of clay, mudstone and sandstone model slopes are “slip-traction-shallow slip”, “slip-squeeze-graded slip slip” and “slip-squeeze-deep push” respectively.The research results can provide reference and guidance for the engineering design and safety evaluation of open-pit mine slopes.