Application of Constant Pressure Grouting with Non-condensable Material to Soft Coalbed Sealing
To solve the problems of bad sealing effect and low pre-drainage gas concentration of boreholes in soft coalbeds,the constant pressure grouting technology with inorganic non-condensable material is proposed.The seepage model of slurry in layer-through borehole is built with COMSOL Multiphysics simulation software,to explore the scope of loosening zone around drainage roadway and borehole,and to analyze the seepage capacity of slurry under different grouting pressures.Eventually,the sealing quality is investigated.Results show that the inorganic non-condensable material has low water separation,high permeability,suspension stability and good plugging performance.After the excavation of No.2164 drainage roadway and the borehole,stress concentration is easy to occur at the shoulder of roadway and the borehole bottom;and the reasonable initial sealing depth of borehole should exceed 6 m.The seepage range of slurry in the sandstone section is larger than that in the mudstone section,and the effective seepage radius of slurry gradually increases with the grouting pressure.Adopting the constant pressure grouting technology with the slurry,the average drainage concentration of boreholes in Puxi coal mine is 51.5%,and the average gas flowrate is 0.005 m3/min,which are 1.35 times and 1.67 times than those with the cement grouting method.
inorganic non-condensable materialcapsular bag sealinginitial sealing depthgrouting pressurefluid-solid coupling
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