Establishment and application of drilling sealing model in the spherical grouting mode based on the loosing-circle theory

There are quite a few studies that have been done on borehole sealing theory both domestically and internationally. The existing researches usually consider drilling of the surroundings as a dense homogeneous elastic body which does not meet the characteristics of real drilling of the fractured body. Based on the loosing-circle theory and analyses of the surrounding rock stress field, cracks and seepage fields, combined with Newtonian fluid spherical grouting model, we deduced the dynamic relationship between the seepage coefficient and rock or grouting parameters of the drilling sealing fluid mode of spherical fissure grouting. In this experiment, mucus was injected in the simulated coal seam and the permeability coefficient of the sealing body was calculated by using the model. To verify the validity of the model, the calculated sealing body number was compared with the extreme negative pressure that the sealing body could withstand. The theoretical model revealed the drilling sealing fluid mechanism, provided a method for the quantitative calculation of the drilling sealing fluid effect by grouting mode and a reference for the subsequent research of sealing mechanism.