a hydraulic system, a pore pressure coupling system and a main body loading system;

wherein the main body loading system is connected to the hydraulic system and the pore pressure coupling system, and is controlled through the hydraulic system to load a sample; and

the pore pressure coupling system is configured to provide water for a true three-dimensional high-temperature, high pore pressure and chemical coupling shear box of the main body loading system to complete a high-temperature, high pore pressure and chemical coupling of the sample;

wherein the main body loading system comprises a frame base;

wherein a rear end of the frame base is provided with a lateral horizontal support platform, and an annular frame is fixed to an upper surface of the frame base through a bolt;

a lower surface of an inner cavity of the annular frame is flush with an upper surface of the lateral horizontal support platform, and the lower surface of the inner cavity of the annular frame is provided with a slide rail extending to the lateral horizontal support platform;

a lateral floating frame is provided on the slide rail through a slider, and a normal dynamic and static combination loading cylinder is fixed in a through-hole in an upper portion of the annular frame;

a tangential disturbance loading cylinder is fixed in a through-hole in a front-side of the annular frame and a tangential hydrostatic loading cylinder is fixed in a through-hole in a rear-side of the annular frame;

the lateral floating frame is of an U-type integrated frame, and a lateral dynamic and static combination loading cylinder is fixed in a through-hole in a right end of the lateral floating frame, and a left end of the lateral dynamic and static combination loading cylinder is connected to a lateral right indenter;

a normal downward indenter is fixed in a vertical through-hole in a middle of the lateral floating frame, a lateral left indenter facing to the lateral right indenter is fixed to a left end of the lateral floating frame, and the high-temperature box is placed in the middle of the lateral floating frame, and the high-temperature box is provided with through-holes in a middle of six surfaces, such as a top, bottom, front, rear, left and right surface;

the normal downward indenter is passed through a through-hole at a bottom of the high-temperature box, the lateral left indenter is passed through a through-hole at the left surface of the high-temperature box, and the lateral right indenter is passed through a through-hole at the right surface of the high-temperature box;

a tangential rearward indenter of the tangential hydrostatic loading cylinder is passed through a through-hole at the front surface of the high-temperature box and a disturbance rod of the tangential disturbance loading cylinder is passed through a through-hole at the rear surface of the high-temperature box; and

the true three-dimensional high-temperature shear box is in the high-temperature box and is provided over the normal downward indenter inside the high-temperature box; and

a normal upward indenter is passed through a through-hole at the top surface of the high-temperature box and then provided on a top of the true three-dimensional high-temperature shear box.