Axial loading system and loading method

The invention provides an axial loading system and a loading method and belongs to the technical field of geotechnical engineering. A first piston and a second piston are arranged in a pipe barrel, a swelling agent is arranged between the first piston and the second piston, the pipe barrel is arranged between a loaded body and a pressure sensor, the second piston is in contact with the loaded body, the loaded body is in contact with a rigid frame body, the first piston is in contact with the pressure sensor, and the pressure sensor is in contact with the rigid frame body. The loading method comprises the following steps that: the pressure sensor is arranged on the rigid frame body; the first piston is arranged in the bottom of the pipe barrel, and the pipe barrel is arranged on the pressure sensor; the swelling agent is filled into the pipe barrel, and a plastic film covers the swelling agent after the swelling agent is tamped to be smooth; the second piston is put in the pipe barrel, and the loaded body is arranged on the upper surface of the second piston; along with the swelling of the volume of the swelling agent, the swelling agent can axially push the first piston and the second piston, and the pressure sensor can be used for recording a value of swelling pressure applied to the loaded body and transferring the value to a statical strain indicator.