Аңдатпа
Purpose. Development and substantiation of an injection-grouting technology for stabilising an aquifer during vertical shaft sinking in a serpentinite rock mass containing alkaline, magnesium-bearing groundwater that limits the effectiveness of conventional cement grouting. Methods. The study included an analysis of the geochemical conditions of water-bearing sublayer IV-4 at the 10th Anniversary of Kazakhstan’s Independence Mine and determination of the geochemical aggressiveness factor Kgc; laboratory testing of two two-component polyacrylate grouts on consolidated serpentinite specimens with a particle size of 0.5-3.0 mm in a water-saturated alkaline environment at pH = 10; microscopic analysis of the polymerisation process; uniaxial compression testing using a GCTS ULT-200 press; and finite element modelling in Rocscience RS3 for the rock mass before and after injection grouting. Findings. The geochemical conditions of the aquifer, characterised by pH = 9-11 and the presence of Mg2+ and HCO3⁻ ions and dissolved SiO2, limit the use of Portland cement because of magnesium-induced corrosion. The factor Kgc = 0.118 represents an 8.5-fold reduction in the load-bearing capacity of the serpentinite rock mass after water saturation. The strength of specimens prepared with the first polyacrylate grout reached 6.1 MPa at Kstr = 2.68, which was 61 times higher than that of specimens prepared with the second grout. Numerical modelling showed that the minimum SF increased from 0.50 to 0.67 and the maximum from 2.85 to 3.83, with a zone of improved stability forming around the shaft. Originality. The combined use of the Kgc and Kstr factors was substantiated for assessing geochemical effects and the effectiveness of serpentinite rock mass strengthening. The interaction of polyacrylate gel with Mg2+ ions was interpreted through the formation of (–COO)2Mg coordination complexes. Practical implications. An injection-grouting scheme was proposed for stabilising the aquifer through 25.0 m long boreholes drilled at an angle of 5°, forming a 0.75 m thick grouted rock zone around the shaft. The use of polyacrylate grout improves the stability of the water-saturated serpentinite rock mass, reduces the likelihood of groundwater inflow pathways, and provides safer conditions for vertical shaft sinking. The proposed technology can be used in mine shaft construction under similar mining-geological and hydrogeological conditions.