Abstract: In order to treat the broken-rock high and steep slope of open-pit mine and improve the slope stability，the slurry flow of high pressure splitting grouting are obtained by calculating the stress field of hydraulic fracture，based on mechanism analysis of pre-stressed anchorage and high-pressure grouting.The pre-stressed anchoring technique of the hierarchical multi-time high pressure grouting combining with advantages of two techniques above is put forward.Then，the contrastive pull-off tests of anchoring shaped models formed by the ordinary anchor solid and multi-time layered high pressure grouting solid are made.The stress distribution data of anchoring bolt are collected and its stress transmission rule is analyzed.It is concluded that the hierarchical multi-time high pressure grouting technique improved the bearing capacity of the anchoring by 39.25%.Meanwhile，it can avoid from the stress concentration.Finally，FLAC3D is used to build a simulation model.Experiments that the same put-off force bears on four groups of different splitting width and four different heights are respectively made to contrast and analyze the distribution and transmission rule of the internal stress.The results showed that comparing with the ordinary anchorage，the hierarchical multi-time high pressure grouting can bear much more shearing strength.With the increase of splitting，the slurry vein length will be longer，the splitting width will be wider and the stress field of slurry vein will have a more significant effect.These result in better anchoring performance.

Key words: Broken-rock high and steep slope, Stability, Multi-time layered high pressure grouting, Pre-stressed anchorage, Pull-off test, Stress analysis, FLAC3D, Wedge model