Research On Structural Optimization Design Of Multi-scale Rock Direct Shear Apparatus

With the rapid development of global economy,the number of high-rise and super high-rise buildings,super large bridges,subway construction and maintenance,water conservancy project construction and other projects is increasing year by year.In order to ensure the safety and stability of buildings,it is necessary to carry out shear strength direct shear test on engineering rock structure samples.In the study of rock mass mechanics,the method of combining direct shear test with engineering geological survey is often used to obtain the shear strength of rock mass discontinuity.In order to improve the reliability of direct shear test data,it is necessary to optimize the design of rock direct shear equipment.This paper mainly carries out static and modal analysis on the main frame and important parts of 1000 k N rock direct shear apparatus.According to the results of static and dynamic analysis,the vertical hydraulic base and left column are determined as the optimization objects.The structure of the vertical hydraulic base and left column is optimized,and the static properties and quality of the main frame before and after optimization are analyzed.The hydraulic system of the equipment is simulated,focusing on the vertical and horizontal hydraulic loading system.The simulation results are analyzed and the hydraulic loading system is optimized.The main contents of this paper are as follows:(1)The three-dimensional model of the main frame of the equipment is established,and its finite element model is further established.Through mechanical analysis and theoretical calculation,the constraint conditions and stress conditions of the main frame are determined.The static analysis and modal analysis of the main frame of the equipment are carried out,and the displacement,stress distribution nephogram,top ten vibration modes,natural frequencies and other parameters of the main frame are obtained.Through the analysis of the main frame structure needs to optimize the part,determine the vertical hydraulic base and left column as the optimization object,lay the foundation for the optimization design of the main frame.(2)The response surface-based optimization method is used to optimize the size of the main frame.After optimization,the static characteristics of the main frame are improved,the maximum deformation of the main frame is reduced by 7.4%,the mass is reduced by 1.2%,and the mechanical performance of the main frame is improved and lightweight.By comparing the static and dynamic performance of the1000 k N rock direct shear instrument before and after optimization,the effectiveness of the optimized design is verified.(3)AMESim software is used to simulate the hydraulic system,and the characteristics of vertical and horizontal loading hydraulic system are analyzed comprehensively.By optimizing the closed-loop control parameters of the vertical and horizontal loading hydraulic system,the vibration value of the actual output force of the vertical hydraulic cylinder is reduced by 51.4%,the horizontal hydraulic cylinder can achieve the accuracy of position control,and the piston speed is controlled below48 mm /min,which improves the stability and loading accuracy of the hydraulic loading system,and better meets the requirements of the shear strength test of rock discontinuity.