Research On Heating System And Hydraulic Servo System Of Integral Rock Mechanics Testing Machine

Rock mechanics testing machine plays an important role in shale gas mining,nuclear waste processing,oil and gas exploration and research of the change of the physical properties of the earth during earthquake.Nowadays,the hydraulic-servo rock mechanics testing machine can draw the ?-? curve of the rock sample when cracking,the chamber can pressurize the rock sample and heat it,but,a machine can draw the ?-?curve,simulate the high temperature under deep underground and be used to observe the crack by CT the same time still can't be found.Then,in this thesis,an integral heating structure rock mechanics testing machine was developed,it's chamber can pressurize and heat the rock sample,during loading,it rotate around its central axis and cooperate with the CT the same time,then the crack in the rock was observed.According to the proposed integral heating structure program,the thesis had design the structure,hydraulic system and heating system,then the heating control system modeling,and calculated the temperature field.Finally,the machine was processed,assembled and debugged,triaxial test and heating test was carried out in the end.The integral structure machine presented in this thesis,rotating by putting on a turntable,use the pressure chamber to act as the reaction frame to avoid blocking the high energy ray,this structure can protect the turntable from the dynamic load.The thesis proposed a heating program that several heating rod was put in the sample base to simulate the high temperature in deep underground,which makes the machine structure compact.In order to increase the rigidity of the machine,the servo cylinder and the pressure chamber was made of one,the axial force was measured by pressure sensor indirectly,and minimizing the elastic parts.However,in the integral structure,the heat from the chamber will transfer to the hydraulic servo cylinder and accurate turntable,then bring difficulty to control the machine.Based on the related theory of heat transfer,the heat transfer boundary conditions of the pressure chamber in several conditions are calculated,such as without heat insulation,with heat insulation,natural convection and forced convection,then,the computational domain was meshed by using ICEM CFD,and the temperature field was calculated by Fluent.Finally,a heat insulation scheme with less influence on the hydraulic system and turntable was determined.Finally,triaxial loading test and heating test was carried out,the ?-? curve was draw.Experiment shows the axial pressure of the machine reach 240MPa,the confining pressure can stabilized at 20MPa,the rigidity of the machine is 0.19GN/m.The heating experiment can reach 200? and control accuracy is ± 0.5 ?,the machine satisfy the rock mechanics testing requirement.