Research On The Combustible Ice Triaxial Test Machine And The Method Of Measuring The Deformation Of The Specimen

Combustible ice is regarded as a kind of clean energy to alleviate global energy exhaustion and climate warming.The development and utilization of combustible ice can meet the increasing energy demand in China.However,combustible ice can only be stable under low temperature and high pressure,and its stability is low.In the process of exploitation,it is easy to cause decomposition,which will lead to serious geological disasters and environmental problems.It is very important for safe and economical development and utilization of the new energy to deeply understand the mechanical properties of combustible ice.Triaxial testing machine is an equipment for studying the strength and deformation characteristics of rock and soil.With the deepening of the research on hydrate,Triaxial testing machine is also applied in the research on the mechanical properties of hydrate.In the triaxial test,LVDT or hall effect sensor is usually used to measure the deformation characteristics of rock and soil,which is easy to interfere with the sample and affect the authenticity of the results.Combined with the characteristics of the rock Triaxial testing machine and according to the functions and requirements of the combustible ice Triaxial testing machine,the following work is completed in this paper:Research on mechanical module of testing machine.In order to achieve the purpose of calculating the deformation of the sample by image processing technology,the pressure chamber is designed.Due to the decomposition and combustion of combustible ice under atmospheric pressure,the traditional sample preparation method is not suitable for combustible ice.In order to ensure the in-situ state of combustible ice,the core pressure maintaining cutting transfer device is studied.Hydraulic servo loading method is selected to complete the axial displacement and force loading,and the core components in the axial loading system are selected and calculated.The mathematical model of each part of the axial compression loading system was built and the transfer function was established.MATLAB/Simulink was used to simulate the system,and PID controller was used to correct the system.The loading system realized the requirements of stability and speediness.To measure the deformation of the sample,the image measurement technology is introduced,and the parts of the image measurement system are designed.The position of the corner point is located based on the sub-pixel corner point detection principle.The corner point is taken as a node according to the finite element method.The strength and tightness of the pressure chamber were simulated.The strength of the pressure chamber was checked by using the Workbench finite element software,and the analysis showed that the main chamber met the requirements of strength and stiffness.By using ABAQUS finite element analysis on the sealing performance of static and dynamic seals of the pressure chamber,it can be known that the sealing performance of the pressure chamber meets the requirements.The research results in this paper provide reference for the development of combustible ice Triaxial testing machine and theoretical support for the calculation of sample deformation by image processing system.