Study on determination of curtain closure grouting parameters offractured rock mass in karst mining area

In order to use curtain grouting to control the formation water damage of karst fissures in mining area,experimental tests were carried out the performance of cement slurries with different water-cement ratios,and the performance and variation of cement slurries with different water-cement ratios were obtained.The curtain grouting pressure and the diffusion radius of cement slurry were studied and calculated by theoretical analysis and numerical calculation.Combined with the hydro-geological conditions of the curtain wall construction area,the construction dimensions of the curtain wall,borehole spacing,grouting pressure and cement slurry selection process were determined comprehensively,which provided a scientific basis for curtain grouting control engineering design.Finally,the closure effect of curtain grouting wall was tested by water release test inside and outside the curtain wall.The closure effect achieved the design purpose and requirements.Therefore,the rationality of the selection of curtain grouting parameters was also verified.The results show that the cement slurry viscosity,stone rate and stone strength decrease with the increase of water-solid ratio,the setting time increases with the increase of water-solid ratio,and the rate of change decreases with the increase of water-cement ratio; the curtain wall thickness is 40 m,the borehole spacing is 20 m and the grouting end hole pressure is 4～6 MPa; the curtain grouting is used to compare the water level change curve inside and outside the curtain wall by water release test.It is by far the most direct means of curtain grouting effect test.