Development and application of tri-axial creep-seepage-adsorption and desorption experimental device for coal

A tri-axial creep-seepage-adsorption and desorption experimental device has been developed to study seep- age law and gas adsorption and desorption characteristics in the process of loaded gas bearing coal rheology. It is com- posed of testing main machine,servo-controlled loading system,triaxial compression chamber,pore pressure control system,adsorption and desorption system,temperature control system,deformation monitoring system and safe guard system. The maximum axial pressure is 500 kN,and the maximum confining pressure is 50 MPa. The heating tempera- ture can reach as high as 90 ℃ ;and the dimensions of tested cylinder samples are ϕ50 mm×100 mm. The advantages of the device are as follows:① It can be used to test the porosity and mechanical parameters of coal and to carry out the gas adsorption desorption and creep-seepage experiments of loaded gas-bearing coal and other experiments as well. The device,in addition,is powerful in function,stable in performance and accurate in testing. ② It can also be fitted to conduct creep-seepage experiments for long time because of adopting the ball screw loading mode. And the maximum loading time can be more than two months. ③ The device is equiped with high and low temperature control system. And it can be used to keep the constant temperature at the gas inlet,gas outlet and the triaxial compression chamber, which can effectively avoid the messurement error caused by temperature variation. Experiments of coal porosity tes- ting,gas desorption characteristics and creep-seepage lawof loaded coal are conducted using this device. These conclu- sions validate the functional diversity,accuracy and reliability in testing on the device.