Mechanism Research On Grout Diffusion Of Vertical Shaft In Water-rich Strata

Grouting technology of water-rich strata has always been an oriented research topic in geotechnical engineering study. While existence of seepage field is one of the major factors of causing construction instability and large-scale geological hazard, construction in watery strata involves problems of jointed rock mass deformation behaviour in seepage field, as well as, fluid-structure interaction mechanism. In macroscopic view, fluid-structure interaction not only intensifies rock mass strength deterioration and surrounding rock mass stress field variation, but also changes rock mass seepage characteristics and seepage filed distribution. Since grouting technology can effectively reinforce surrounding rock, improve complex geological conditions, and solve underground water disaster problems, it has wide application prospect in engineering field.Base on Xizhuo Coal Mine Air Return Shaft Project, this paper focuses mechanism research on grout diffusion of vertical shaft in water-rich strata. Firstly, by applying damage mechanics and fracture mechanics theories, this research paper expounds damage effects of fractured rock mass under the action of fluid-solid coupling and crack damage evolution constitutive equation. While analysis rock mass fracture damage, due to the limitations of constitutive model built-in FLAC3D numerical simulation software, Visual Studio 2005 is used to compile dynamic link library in order to create a custom crack damage evolution constitutive model and importing it into FLAC3D for further study. Secondly, focusing on numerical simulation of vertical shaft wall after grouting to analysis the reason for rock mass fracture initiation, expansion, joint, and gradually buckling failure, this research paper compares different grouting pressure failure area and crack initiation expansion area. The numerical analysis shows that splitting had no significant effect in 1-3MPa grouting pressure which the amount of slurry injection is difficult to ensure, therefore, grouting effect is inconspicuous. When the grouting pressure increases to 4MPa, the surrounding rock fissures occur splitting, the slurry can be spread to surrounding rock depths, thus effectively strengthening the surrounding rock. And when the grouting pressure increased to 6MPa, surrounding rock appeared displacement and failure trends. Therefore, for such grouting, grouting pressure should be controlled in 5-6MPa. Thirdly, combining with a specific project study to analysis the diffusion mechanism of working face pre-grouting, this research paper study the effect on the stability of surrounding rock and grout diffusion.Describe the design process of shaft grouting amply. The results show that when grouting pressure in 3MPa, slurry is difficult to inject. When the grouting pressure increased to 6MPa, surrounding rock appeared instability and failure. Therefore, grouting pressure should control within 4-5MPa. Finally, combining with the practical examples to verify the results of numerical simulation, the calculation results show that the strength and stability all meet the design requirements, which verify the rationality of the results of numerical simulation.