| With the promotion of bridge,high-way and railroad engineering construction in China,the volume of construction of tunneling shaft has increased accordingly,and the umbrella drilling equipment is the current major equipment for completing shaft tunneling by drill and blast method.As the front-end actuator of the drilling device,the working parameters of hydraulic rock drills has great impact to the drilling performance in terms of drilling efficiency,the drilling speed and the fatigue life of the drill tool,etc.So in order to promote the rock breaking capability of the drilling,this thesis investigates the rock breaking characteristics of the rock drill by targeting the hydraulic rock drill drilling system.Firstly,the analysis of geotechnical and drilling tool impact theory was carried out,and the numerical analysis model of piston-drilling rod-drilling bit-rock was established based on finite element theory and three-dimensional model;secondly,the analysis of rock crushing process and drilling system performance characteristics was carried out to explore the influence of different drilling parameters on drilling performance;based on the results of dynamic response analysis of drilling rod under multiple working conditions,the fatigue life of drilling rod under different working conditions was obtained.Finally,drilling parameter-drilling performance Kriging proxy model is established by Latin hypercube sampling,the optimal drilling parameters were obtained by solving the agent model under the constraints using the improved sparrow algorithm.The main research of this thesis is as follows:(1)Establish a three-dimensional numerical model of the rock drill drilling system.Based on the working principle of rock drill impact rotary rock breaking,the theoretical introduction and analysis are carried out from two perspectives of rock mechanical properties and drilling tool impact process.The main strength and elastic-plasticity theories of rocks are introduced,and a suitable intrinsic structure model is selected as the granite material intrinsic structure;the piston impact process and drill bit breaking force are analyzed,the mechanism of rock breaking by ball tooth tools is explored,and a numerical analysis model of rock breaking by impact is established based on the threedimensional model of the impact system and the finite element theory.(2)The rock breaking process and rock breaking characteristics of the rock drill are analyzed.Based on the three-dimensional numerical model,the stress changes and damage changes of rock surface and special location units during rock breaking process are analyzed.The four drilling performance indexes of rock breaking work,rock breaking speed,rock drilling reaction force and drilling displacement are introduced,and the influence of different drilling parameters and working conditions on the drilling performance indexes is investigated by changing the piston impact speed,drilling rod rotation speed,drilling pressure of drilling system and the magnitude of ground stress.(3)To carry out kinetic and fatigue life analysis of rock drilling rods under multiple working conditions.Constrained modal analysis of gouge drill pipe is carried out according to the modal analysis theory to determine the low-order inherent frequency of drill pipe,which provides reference for avoiding resonance phenomenon in actual construction.To address the problem of complex stresses and failure of gouge drill pipes in the actual drilling process,the kinetic analysis of the drilling process under multiple working conditions is carried out to investigate the stress distribution of drill pipes under different working conditions,and the fatigue life of gouge drill pipes under different working conditions is obtained based on the results of the drill pipe stress analysis combined with the fatigue accumulation damage theory.(4)The drilling parameters-drilling performance Kriging proxy model was established to optimize the drilling parameters.The Latin hypercube sampling is used for experimental design,and the Kriging proxy model of drilling parameters and drilling performance with compound accuracy requirements is established;in order to make the drilling parameters optimization results accurate,the improved sparrow algorithm is proposed,and the basic sparrow algorithm is improved by introducing Tent chaos mapping,positive-cosine algorithm and Lévy flight strategy with multiple strategies,and the feasibility of the algorithm is verified by solving the test function.Considering the uncertainty of ground stress magnitude in the drilling process,the ground stress is used as a fuzzy variable to establish a constraint model for drilling performance optimization.Finally,the improved sparrow algorithm is used to solve the Kriging model of drilling performance under the constraints and obtain the drilling parameters that satisfy the conditions,which provides theoretical guidance for practical engineering applications. |
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