Study On Measurement And Control System Of Triaxial Tester With High Confining Pressure

In the field of civil engineering,the stability and deformation of soils play a decisive role,especially in the external role,in the earthquake,waves and other vibration load will make the nature of soil samples change,greatly increased the construction safety hazards.In order to complete the seismic design,before the construction,the experimental simulation of building materials is very important to simulate the real stress conditions,the conventional case for the treatment of these soil samples in the laboratory through the triaxial instrument for analysis,to get material construction aspects of the various parameters.At present,the dynamic three-axis is a low confining pressure loading,usually less than 1Mpa pressure,by the Dalian University of Technology Institute of earthquake research commissioned to develop a 300-meter hydropower dam for the high-pressure three-axis test,the high-pressure triaxial test Instrument can achieve 3Mpa high confining pressure to study the 30 meters underwater dam foundation load conditions.The dynamic loading is to simulate the physical parameters in the earthquake case.The main contents of the study include the design of a reasonable and feasible test system.The influence of the inertial force on the dynamic loading of the high frequency small load is studied.In the liquefaction experiment,The problem of amplitude decay in dynamic loading control.In this paper,the specific work is as follows:First of all,for the high confining pressure triaxial instrument system,read the domestic and foreign literature,its background and development of a detailed understanding of the analysis of the dynamic triaxial instrument composition and working principle,and then the system problems further research.According to the needs of the project,the use of hydraulic servo loading,measurement and control system program confining with Siemens PLC,axial use of NI data acquisition card.The system is designed from the mechanical module,the hydraulic module and the electronic control module respectively.Finally,the design of the whole experimental device is completed and the assembly and debugging work is completed.Then in the course of scientific experiment,the large acceleration will produce a large inertial force when the dynamic loading,the inertial force will affect the control accuracy of the load,resulting in the experimental accuracy of the decline.In order to study the effect of inertial force on axial loading under high frequency and low load,the mathematical model of dynamic triaxial tester is established,and the influence of inertia force on experimental precision is analyzed.In the MATLAB / Simulink environment,the dynamic analysis of the system is carried out.The influence of the inertia force on the inertia force is studied under the condition of high frequency and low load.The method of iterative learning control is put forward,and the proposed control theory is carried out.Simulation analysis,the maximum error from 17 N to 5N.Finally,in the liquefaction experiment,the fuzzy control scheme and the fuzzy control have better adaptive ability and better dynamic performance for the loading object with nonlinear and parameter variability.According to the experiment,the design of the fuzzy rules is completed and the simulation and experimental verification are carried out.Compared with the conventional PID,the fuzzy PID can effectively solve the problem of amplitude attenuation in liquefaction experiments.