Research On The Breaking Mechanism Of Particle Water Jet Impact Rock

The exploration and development of deep hard stratum is faced with slow drilling speed,long production cycle and high cost of capital,which presents new challenges to drilling technology.Particle impact drilling rock hard steel on high speed spherical particle impact breaking rock is given priority to,at a high speed of hydraulic rock fragmentation and mechanical tooth broken rock is complementary,a new method for drilling rock some special strata section can be used for drilling,especially due to very high compressive strength,by hard formation drilling rate.Based on theoretical analysis,numerical simulation and experimental research,the dynamic response of rock under the impact of particle jet and its mechanism of damage evolution and destruction are investigated.With elastic-plastic mechanics,continuum mechanics,the basic law as the foundation,combined with the energy conservation equation and basic characteristics of the spherical wave,a mathematic model of the particle impact contact rock,deduces the spread of stress wave in rock medium wave equation,to determine the rock under the action of particle impact stress component,by embedding the tensile strength and shear strength as write rock failure criteria of rock particle degree of stress calculation,and through smooth particle hydrodynamic research method(SPH)and finite element method(FEM)coupling algorithm verification,get the rock under the action of impact dynamic response and failure form.On this basis,by using ANSYS/ls-dyna software,respectively established the numerical model and the jet impact rock particles impact drill rock numerical model,analyzed the particle diameter,incident Angle,incidence rate,confining pressure,rotating speed and nozzle Angle combination on the rock stress field distribution and the influence of rock damage forms.Respectively carried out the rock particles jet shock experiment and particle impact drill rotating rock experiment,indoor experiment results compared with the results of numerical simulation,and further reveals the dynamic response of rock under the effect of particle jet impact characteristics and broken mechanism.Research shows that: under the action of a single particle impact presents three kinds of rock stress state,the first compression after stretching,three to compressive stress,tensile stress state and rock main damage forms for tensile failure and shear failure,stretching-shear joint destruction;Rock unit under the effect of particle jet impact changed four stages,namely initial shock stage,stable constant shock stage,the erosion damage stage and elastic recovery phase,the failure modes are mainly shear failure and tensile failure,the failure of compression and shear-tensile failure;Particles under the action of impact drill rotating,rock mainly takes the form shear failure and tensile failure form,the Angle between the nozzle combination has great influence on rock fragmentation,and the rotation of the drill bit smaller effects on rock fragmentation effect;The numerical simulation results are consistent with the experimental results and can reflect the dynamic response characteristics of the rock under the action of particle jet.