Design And Performance Research Of High-pressure Foam Apparatus For Rock Fragmentation

The mining of coal resources in deep strata have posed new challenges to rock roadway excavation.The drilling and blasting method has the defects of low degree of mechanization,low safety factor and poor controllability.The tools of the tunnel boring machines are severely worn and cannot achieve economical cutting.Hard rock roadway excavation has become a bottleneck restricting the efficiency of coal resource mining in our country.Based on the fact that the tensile strength of the rock is much smaller than the compressive strength,the technique of high pressure foam bursting is put forward in this thesis.This thesis uses the method of mechanism design,theoretical analysis,simulation and experimental verification to systematically carry out the research on the key issues of the high pressure foam apparatus for rock fragmentation.The advantages of foam as a fracturing medium are analyzed based on the defects of the existing hydraulic rock breaking technology and the characteristics of the foam medium.According to the working process of the fracturing apparatus and the characteristics of the foam medium,two high-pressure foam apparatuses for rock fragmentation are designed,namely the impact type and the instant injection type.Based on the dynamics and fluid mechanics theory,the mathematical model of fracturing pressure of the apparatus is derived.The influence of the main structural parameters on the performance of the apparatus is researched,which provides a theoretical basis for the design of the apparatus parameters.The rock breaking effects of the two apparatuses are compared,and the final design plan is determined.In order to improve the sealing ability of the apparatus' s sealing system,the theoretical model of the deformation of the packer rubber during the sealing process is established,which is based on the theory of rubber's deformation and elastic mechanics.The relationship between the deformed state and the force of the packer rubber is explored.The sealing process of the drill hole is simulated by ABAQUS and the influence of the sealing load,inclination angle of end face and rubber hardness on the sealing performance of the packer rubber is analyzed,which is used to determine the optimal design parameters of the packer rubber.The structural parameters of the instant injection high pressure foam apparatus for rock fragmentation are designed in detail.Meanwhile,the rock breaking mechanism of the apparatus is researched.Based on the working process of the high-pressure foam apparatus,a high-pressure foam test system for rock fragmentation is designed,which is composed of high-pressure foam generation system,high-pressure foam apparatus,signal acquisition system and power control system.Based on the theory of similar matching of material,three kinds of rock samples with different hardness are prepared,whose mechanical properties are measured.The variation trend of system pressure during fracturing and the influence of fracturing medium,medium injection mode,mechanical properties of rock samples,system pressure on rock breaking performance of fracturing apparatus are studied by high-pressure foam test system for rock fragmentation.This thesis has 55 pictures,15 tables and 110 references.