## 6 Conclusions  
By establishing a calculation model for a high, steep slope, the relationships linking the displacement of the slope foot and the force on prestressed anchor cables with the strength reduction factor of a rock mass were investigated. On this basis, the restriction of displacement of a sliding mass in the slope by applying cable prestress and the changes in cable force under different prestresses were attained. Through comprehensive analysis, the reinforcement mechanism of prestressed anchor cables in a high and steep slope was acquired and the method for optimising the reinforcement scheme involving such prestressed anchor cables in the slope was proposed. The following main conclusions were drawn:  
1. With increasing cable prestress, the safety factor of the slope increased. However, cable prestress was not linearly correlated with the safety factor of the slope. After the prestress was increased to a certain value, the growth in the safety factor decreased until further increases in cable prestress exhibited no significant beneficial influence on the safety of the slope.  
Figure 13: Relationship between the displacement of the slope foot and the increment thereof in cables at the slope foot.  
2 Based on previous research, the reinforcement mechanism of prestressed anchor cables on a high, steep slope was as follows: on the one hand, the cables improved the stress state in rock and soil masses within the compression zone on the surface of the slope and slowed down the degradation of the mechanical properties of the slope rock and soil masses. More importantly, on the other hand, prestressed anchor cables can directly restrict the displacement of the soil so as to slow down the sliding of the slope, thus improving the slope stability.
3 To reduce the number of cables required, increase the ease of construction, and save money, it is suggested to remove the prestressed anchor cables from the upper part of the slope. Then, by increasing the cable prestress at the lower part of the slope and reducing the cable prestress in the middle part, the safety factor of the slope can reach codified requirements.
4 The incremental cable force was linearly correlated with the displacement of the slope foot. The slope stability can be comprehensively evaluated by monitoring the changes in cable force in the lower part of the slope and utilising data pertaining to slope displacement.  
Conceptualization, J.L. and L.J.; methodology, S.C.; validation, J.L., S.C. and L.J.; writing--original draft preparation, J.L.; writing--review and editing, F.Y.; visualization, F.Y.; supervision, L.J.; funding acquisition, S.C. and F.Y. All authors have read and agreed to the published version of the manuscript.  
The work was supported by the Science and Technology Project of Hubei Provincial Transport Department 'A remote monitoring and warning system for operation safety of highway slope in the western Hubei mountainous region' (2016-600-1-1) and the National Natural Science Foundation of China 'Regenerative evolution of fissures and multiple fissures network model of expansive soil' (No. 41702337).  
On behalf of my co-authors, I declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, \"Reinforcement mechanism and optimisation of reinforcement approach of a high and steep slope using prestressed anchor cables\".