Study Of Coal Rock Fracture Characteristics Of Water Jet Perforation Under The Action Of Circumferential Pressure

For the applicability of water jet punching and pressure relief permeation technology and the effect of coal seam permeation enhancement,a combination of analysis,numerical simulation and mechanical experiments was used to study the characteristics of rupture after breaking and perforation to reveal the development law,factors and action law.Analyzing the process of breaking by using display dynamics software,the fracture pattern,development state was investigated.with or without perimeter pressure,the mechanism of pore formation,horizontal,vertical fissures extending into a fissure network by the percussion was elucidated;the pressure profited further fissure development,and the range increased when the pressure was loaded.Based on the results,simulation experiments were designed to analyze the different formation effects,morphology and fissure development characteristics of raw and coal type under the same parameters;the depth and size of high-strength raw coal are lower than type,but the kinetic energy is easier to spread on the surface,resulting in further fissure extension;the pores continue to deepen when the jet is not submerged.When it is submerged,the pores cannot expand,forming wedge-shaped pores;under impact damage,the bottom of the hole expands,forming an ellipsoidal-like shape.Similar material experiments were carried out,and the full-field strain and acoustic emission systems were used to analyze the deformation pattern and development characteristics under stress.The structure of the water jet-formed coal body was changed.The fissures were continuously expanded.A model of elliptical-like pore was established,analyzing deformation characteristics,the amount and the deformation relationship;the amount of coal was positively correlated with the maximum main displacement at the top.The more coal exiting,the more fully the fissures were developed.A numerical model under load is constructed to analyze the damage characteristics of the pore-forming body,revealing the differences under uniaxial and biaxial loads.Figure 40;Table 13;Reference 59...