Surface subsidence control technology of multi-bed separation grouting

In order to enhance the injection ratio to meet the surface subsidence controlling requirements without obvious thick-and-hard strata in overburden for generating large-scale bed separation, the multi-bed separation grouting method is proposed in this paper. The scale model test is used to study the spatiotemporal evolution of overburden due to multi-bed separation grouting. The field measurements is proven that multi-bed separation grouting can successfully mitigate overburden failure and subsidence by increasing the boreholes number, and multi-bed separation grouting has successfully applied in Huaibei mining area. Filling masses with different diffusion radii are commonly formed in the different bed separation, which can effectively support the overlying. The surface subsidence reduction ratio can reach 79.92%. The formula for injection quantity calculation can accurately predict the overburden grouting with an accuracy rate of over 91%, providing the beneficial guidance for the overburden grouting engineering and the reference for the prediction of subsidence reduction rate. This research presents an effective and cost-efficient approach for addressing the surface subsidence, and expands the application scope of overburden grouting is expanded.