Gas bearing shale absorption strain testing device and method under confining pressure bias pressure constant temperature environment

The invention discloses a gas bearing shale absorption strain testing device and a method under confining pressure bias pressure constant temperature environment and belongs to the field of rock engineering and unconventional natural gas engineering. The testing device comprises a triaxial pressure chamber, an axial pressure control system, a confining pressure control system, an upper end gas injection system, a lower end gas injection system, a vacuum pumping system, a constant temperature system and a data control collecting system. The gas bearing shale absorption strain testing method comprises firstly calibrating the sample deformation testing error caused by gases between samples and gaskets and the samples and thermoplastic pipes under the testing condition; then calibrating gas bearing shale swelling deformation caused by non-absorption gases under the testing condition; finally testing and calculating gas bearing shale real absorption deformation caused by absorption gases. The gas bearing shale absorption strain testing method has the advantages of separating gas bearing shale swelling strain caused by free state gases and absorption gases, achieving accurate measurement of real absorption strain, providing deviatoric stress and constant temperature environment for absorption testing and enabling tested swelling deformation to be accurate and confirm to engineering practice.