Numerical Simulation of Crack Initiation and Propagation Evolution Law of Hydraulic Fracturing Holes in Coal Seams Considering Permeability Anisotropy and Damage

Hydraulic fracturing has been widely used in practical engineering as an essential means to prevent coal seam gas outburst, increase permeability and improve drainage efficiency. Accurate prediction of fracture propagation law is important basis for optimizing parameters achieve high-efficiency seams. In this paper, a new seepage–stress–damage coupling model considering anisotropy first established then study the evolution laws crack initiation pressure (σci), (σcd), AE behavior pore water with lateral coefficient (ξ) (λ) process hydraulic fracturing. Finally, influence initial on σci discussed, efficient method proposed. Research results indicate that: situ stress still plays leading role approach whether isotropic or anisotropic; non-uniform condition favorable growth compared uniform under condition; when direction maximum consistent principal (ξ = 0.5, λ < 0), seams are easily fractured; holes can be divided into three stages: stage, smooth expansion stage breakdown any ξ; more complex distribution, area release zone (GPRZ) increases, which very beneficial drainage. This provide technology improving efficiency using method.