Research On The Damaging And Fracturing Characteristics Of Coal Medium By Pulsated Waterpower Hammering With High Pressure

Enlarging the gas discharging range is essential to improve the gas drainage ratio of high gas and low permeability coal seam. Seam pulse water injection technology is a new kind of exploitation of Coal-Bed Methane(CBM) technique, which is proposed based on conventional water injection technology, and the technology through the effect on the coal wall stress caused by periodic changes, and coal body contraction-expansion-contraction deformation, damage cumulative fatigue effect, changing the water injection sphere of influence and exhausting C BM, so it is important to reduce low permeability coal mine safety.In the paper by means of numerical simulation and field experiment of combining theoretical analysis, carried out a systematic research on coal seam pulse water injection technology.First of all, in the basis of previous studies analyzed the propagation of pulse water injection pressure in coal. Analysis of the impact of fluctuating pressure loads of coal body, combined with the fracture mechanics and damage mechanics theory, the deformation law of pore, fractureand other defects with the strength of coal and coal in the pulsating load damage analysis,and analysis water and gas displacement mechanism of the process of coal seam water.Secondly, using ANSYS power module of pulse water injection process in the whole should change rule of displacement force. Seen from the simulation results, in order to achieve optimal water fracturing effect, it should be under the premise of running to meet the equipment to maximize the amplitude pulsating loads, load difference and frequency;Again, anslysis of seepage and stress in coal seam water injection process coupling process, introducing the concept of effective stress in porous media to describe the force between particles of coal framework, obtains the coal body seepage field-coupled rules of stress, seepage using ANSYS module to simulate the coal seam water injection, two developed the software using Fish language, optimized post-processing function, also analyzes the influence of different factors on the effect of coal seam injection. Seen from the simulation results, in order to achieve better results coal injection, water injection must guarantee a certain time and injection pressure. Pulsating pressure load s on the media damage, and crack formation increases the effective area of water, and significantly enhances the scope.Finally, Physical simulation test of hydraulic fracturing of coal is designed, and the hydraulic fracturing test of three coal samples is carried out. Preliminary experimental results show that: water media produces irreversible damage, the greater the distance water holes, the smaller the amount of damage; at the same payload type, load the greater the greater the amount of damage; Pan three coal samples pulsats water than high static pressure water injection 80 %, and it describes the advantages of pulsating water injection technology, and verifies the correctness of the numerical simulation.