Research And Application Of The True Triaxial Coal Stone Coupling Test System

In recent years,great progress has been made in the research on the true Triaxial test equipment at home and abroad,which has played an important role in the development of rock-soil mechanics.This project is a collaboration with Heilongjiang University of science and technology,Based on the true Triaxial rock mechanics testing technology and the coal and gas outburst test technology,a set of true Triaxial Coal Stone Coupling test device is designed,It is used to simulate the influence of coal mine on the dynamic disaster of coal mine under the three direction unequal principal stress,high gas pressure and high temperature,Coal and gas outburst test can also be carried out separately.This paper is mainly from the following aspects:First,according to the functional requirements and parameters,a set of 4MN true triaxial coal stone coupling device is designed,Complete the design of the working principle,including the design of hydraulic pressure control principle,which can meet the functional design requirements in theory,So that it can realize the synchronous loading in three directions in principle,not only has the higher synchronization precision,but also needs to have the better load stability.The device can realize uniaxial biaxial loading and three axis loading.The heating system can be used to heat the box to provide a test temperature environment.The pneumatic system is filled with a gas with a maximum pressure of 8MPa.Secondly,complete the specific design of the structure,Combined with the true triaxial rock mechanics testing technology and coal and gas outburst test technology,I need to design a high rigidity hydraulic loading true triaxial test device.The parts have good technology,the key components such as the finite element analysis,the strength and stiffness to meet the design requirements.The design of a synchronous cylinder and control system can realize the synchronization of force and displacement in the same direction,The device can realize stable loading and unloading by adopting double valve parallel connection.The method of static pressure unloading is used todesign to reduce the blank angle effect.Thirdly,a test system is designed,It can realize the real-time data acquisition and processing in the whole test process.Including the measurement of stress and strain,temperature and air pressure.For the reason of the structure,the test data of the real three axis test machine is more difficult to use.Pressure and compression are indirect measurement.Temperature and pressure are measured by direct measurement.The measurement of the strain of the specimen is carried out by the combination of the one point measurement method and the internal micro strain measurement method.The global strain is obtained indirectly by compression.The local strain of the specimen was measured by installing the extensometer inside the specimen.The acoustic emission system is used to collect the acoustic emission signal during the test,The acoustic emission positioning principle is used to locate the position of the acoustic emission source in the test piece,and the acoustic emission signal is received by eight sensors installed in the two heads.Finally,the value of pressure and displacement is obtained by indirect measurement,Through the establishment of mathematical model,the result of uncertainty evaluation is introduced.