the device body is provided therein with a working chamber;

the specimen fixing mechanism comprises two specimen fixing heads that are arranged opposite in the working chamber; and corresponding positions of the two specimen fixing heads are respectively provided with specimen fixing parts;

the shear testing system further comprises a power conversion assembly and a triaxial cell;

the device body comprises a device base, support rods provided on the device base, and a device cover provided on top ends of the support rods;

the working chamber is a space between the device base and the device cover;

the device body is provided with a first mounting position and a second mounting position that are respectively corresponding to the two specimen fixing heads; the two specimen fixing heads comprise an upper specimen fixing head and a lower specimen fixing head that are arranged above and below; and the lower specimen fixing head is fixedly connected to the device base;

the first mounting position of the device body is corresponding to the upper specimen fixing head, and only the first mounting position is provided with the power conversion assembly; and

the power conversion assembly comprises a torque output component, a power input component, a transmission mechanism, and an axial pressure mechanism;

the torque output component is annular in shape; and the torque output component is rotatably provided on the device body, fixedly connected to the corresponding upper specimen fixing head, and able to drive the upper specimen fixing head to rotate relative to the lower specimen fixing head;

the power input component is coaxial with the torque output component and linearly movable;

the transmission mechanism is in transmission connection with the torque output component and the power input component, and is able to convert a linear motion of the power input component into a rotational motion of the torque output component;

the transmission mechanism comprises a gear ring located on a top surface of the torque output component and surrounding the power input component, gear racks located on the power input component and distributed along a centerline of a motion trajectory of the power input component, and shaft gears rotatably provided on the device body and engaged with the gear ring and the gear racks, respectively;

the axial pressure mechanism comprises a pressure shaft slidably provided inside the power input component; an inner end of the pressure shaft sequentially passes through an inner end of the power input component, the torque output component, and the upper specimen fixing head connected to the torque output component, and extends to the specimen fixing part of the upper specimen fixing head; and an outer end of the pressure shaft is provided with a sliding groove;

the axial pressure mechanism further comprises a piston that is slidably provided in the sliding groove of the pressure shaft and forms a pressure chamber with the sliding groove; the pressure chamber is filled with a pressure medium; and the pressure medium is configured to generate a pressure to make an outer end surface of the piston flush with an outer end surface of the power input component; and

an inner chamber of the triaxial cell forms a triaxial pressure chamber; the triaxial cell is provided with a pressure rod through-hole for a pressure rod to penetrate into the triaxial pressure chamber; the triaxial pressure chamber is provided therein with a heating element; the device body is located in the triaxial pressure chamber; and there is at least one power input component corresponding to the pressure rod through-hole.