Study on curtain grouting parameters of vertical shaft in Dengying formation of southern Guizhou with thick aquifer

The dolomite of the Dengying formation on the roof of the Sinian phosphorite layer in southern Guizhou is directly filled with water, and the hydrogeological conditions are complex, which are the main factors restricting mine construction. Ground pre-grouting technology is an effective means of preventing water in shafts. It has been successfully applied in coal mines, iron mines, lead-zinc mines and other mines. In view of the complexity of the hydrological conditions of the dissolution dolomite aquifer water diversion network, existing shafts cannot be copied the design parameters of grouting curtain. In order to obtain a reasonable design method for curtain grouting parameters of the dolomite aquifer in the Sinian Dengying formation in southern Guizhou, this paper used a variety of research methods such as theoretical analysis, laboratory tests, industrial tests, and engineering analogy to conduct analysis on the dissolution fissures of the dolomite aquifer. The characteristics of water network and the diffusion law of clay cement slurry were systematically analyzed, and the injectability of the pre-injected clay cement slurry on the surface of the Dengying group aquifer and its influencing factors were summarized and evaluated; Compared with the detection of grouting effect and other factors, the curtain grouting parameters of vertical shafts in the Dengying formation of southern Qiannan have been studied in depth, combined with similar engineering cases to determine the pre-grouting parameter design for the dissolution-type Dengying formation dolomite. The results show that the clay cement slurry is injectable in the aquifer of Dengying formation,the spacing between holes should be 4.0～4.5 m, and the range of grouting parameters such as the specific gravity range of the finished clay cement slurry, the height of the grouting section of stable formations of 70～100 m, and the height of 30～50 m of the grouting section of broken formations are recommended. The grouting termination criteria must also meet the design grouting volume and grouting final pressure requirements. The research results can provide a useful reference for the design of shaft water hazard prevention and control schemes for vertical shafts in dolomite aquifer of Dengying formation in southern Guizhou.