Shield Mechanism Of Vibrating Excavation Geotechnical Studies And Numerical Optimization Drag Reduction Law

Shield equipment is an important large-scale tunnel excavation and paving machine at this stage.It is widely used in various urban areas in China today.The application of rock and soil vibration excavation technology can effectively reduce the resistance and energy consumption of the shield machine.The dissertation focuses on the mechanism and laws of rock and earth excavation to reduce drag,adopts theoretical analysis and finite element numerical simulation methods,and combines shield deck dynamic test bench design and related excavation experiments to study the shield cutters and cutter heads.Numerical modeling technology of rock and soil vibration excavation process,law of vibration and soil erosion reduction of geotechnical shields,and optimization of parameters of cutterhead vibration excitation.The main work includes:(1)Analysis of Mechanism of Drag Reduction in Soil Vibration.By studying the trajectory of the vibration of shield cutters and cutterheads,the dynamic load analytical method in the soft soil excavation of shield cutters is deduced,and the soil vibratory excavation working mechanism is analyzed based on the physical properties of the soil and the dynamic and static strengths.(2)Research on Soil Drucker-Prager Constitutive Model Correction and Numerical Modeling and Solving Method of Rock and Soil Vibration Cutting.The suitable soil constitutive model was selected according to the shield vibration drilling and the geological and soil characteristics of Hangzhou.The soil physical properties parameters were obtained through rock and soil triaxial tests,and the Drucker-Prager constitutive model was corrected.The numerical FEM and DEM modeling were used.Soil analysis and comparison of Lagrange's and ALE's numerical methods for solving soils,and numerical simulation methods for numerical modeling and vibration digging of rock and soil vibration cutting.(3)Based on LS-DYNA,the numerical model of vibration digging for the shield cutter is established.The Drucker–Prager modified constitutive model and the continuous concrete cap model were selected for the Hangzhou geology,ie,the middle and lower reaches of the Yangtze River.The numerical models of the vibratory excavation of the shield cutters and hobs were established,and the loads were compared by vibration excitation and uniform speed.The change of energy consumption and the change of damage cracks in the concrete are studied.The influence of vibration parameters on the load and energy consumption of the excavation is studied.(4)The Establishment of Numerical Model for Excavation by Shield Cutters and Study on Optimization of Vibration Parameters.The numerical model of shield cutter plate excavation was established with the soil sample of Hangzhou Metro Line No.1.It was analyzed that different applied stimuli were applied in the direction of the cutterhead and in the direction of the cutterhead.The excitation parameters of the cutterhead were used to advance the resistance and cutting resistance of the cutterhead.The relationship between torque and driving power consumption and the law,and use of ANSYS / LS-DYNA optimization design process and tools(LS-OPT)to achieve the shield cutter disk vibration excavation in line with the excitation parameters of multi-objective optimization solution and analysis,single After the cutter optimization,the cutting resistance is reduced by 57.5%,the propulsion force in cutterhead cutting is reduced by 1%,and the torque is reduced by 17%.(5)Design and manufacture ?800 mm shield vibration excavation experimental platform.The experimental platform realized the active vibration excitation and excitation frequency and amplitude parameters of the cutter head in the circumferential direction and the advancing direction of the shield.Finally,the dynamics test experiment of the shield cutter disk vibration of the soil was carried out.The relevant experimental data and the numerical value of the paper Comparison of simulation results.The results show that the experimental results and the stable numerical range(propulsion force 0 to 7500 N,torque 0 to 5000 N×M)are consistent with the aforementioned theoretical analysis and numerical modeling simulation.In this dissertation,the application of vibratory excavation on shield cutters and cutterheads was studied to study the mechanism of drag reduction in rock and soil vibration.The optimal vibration parameter combination for shield cutterhead under specific conditions was designed by orthogonal test and optimization analysis.The oscillating vibration excavation experimental platform of ?800 mm with adjustable excitation parameters was manufactured.