Three-dimensional water-absorption swelling multifunctional experimental machine and method for chemical swelling rocks

A three-dimensional water-absorption swelling multifunctional experimental machine for chemical swelling rocks, characterized in that it comprises a triaxial high-temperature and high-pressure reaction chamber, wherein the triaxial high-temperature and high-pressure reaction chamber is respectively connected to a confining pressure loading controller, a water pressure loading controller, a temperature controller, an axial pressure loading controller, a pH value monitor and a data acquisition and analyzer;

• the triaxial high-temperature and high-pressure reaction chamber comprises an upper end cover and a lower end cover which are detachable at upper and lower ends;
• an internal cavity and an external cavity are provided between the upper end cover and the lower end cover;
• the external cavity is sleeved outside the internal cavity;
• a sealing liner sleeve is provided between the internal cavity and the external cavity;
• an upper convex body and a lower convex body protruding toward one side of the external cavity are provided at upper and lower ends of the sealing liner sleeve;
• an oil cavity is provided between the upper convex body and the lower convex body;
• and force transmission pads are provided between the upper convex body and the upper end cover and between the lower convex body and the lower end cover;
• a rock sample is provided in the internal cavity, and a water-permeable pressure hoop is arranged outside the rock sample, the outer wall of the water-permeable pressure hoop is in close contact with the sealing liner sleeve, and the sealing liner sleeve is connected to a circumferential stress-strain sensor via a displacement structure;
• an upper pressure head is arranged above the rock sample, a water outlet pipe connected to the rock sample is arranged in the upper pressure head, a lower pressure head is arranged below the rock sample, a water inlet pipe connected to the rock sample is arranged in the lower pressure head, and an axial pressure loading screw pressure head is detachably connected to the top of the upper pressure head;
• the water-permeable pressure hoop comprises a plurality sections of hoop bodies with joints, and the hoop bodies are respectively provided with axial water-passing grooves and radial water-passing holes;
• the displacement structure comprises a compression cavity, holes are provided at both ends of the compression cavity, a displacement rod is provided in the compression cavity, both ends of the displacement rod extend out of the holes, one end of the displacement rod is in close contact with the sealing liner sleeve, and the other end is connected to the circumferential stress-strain sensor via a connecting plate, a portion of the displacement rod located in the compression cavity is provided with a convex body and a force adjustment spring, the convex body is located on the side close to the sealing liner sleeve, the force adjustment spring is sleeved on the non-convex body portion of the displacement rod, and the outer diameter of the convex body is greater than the radial dimension of the hole.