Tri-axial mechanical test apparatus and method for simulating the process of freezing high-pressure water into ice

A tri-axial mechanical test apparatus for simulating a process of freezing high-pressure water into ice, wherein said apparatus comprises:

• a main body loading system;
• a freezing system, and
• a sample test system,
• wherein the main body loading system comprises:
• a flange;
• a pressure-bearing shell;
• an axial pressure piston;
• a sample base;
• a liquid inflow loading pipe;
• an exhaust pipe;
• and
• an insulating layer,
• wherein the flange, the pressure-bearing shell and the axial pressure piston are constituted to a loading main body,
• wherein the flange is in a stepped shape, snap-fitted to a bottom of the pressure-bearing shell, and connected to the pressure-bearing shell by hexagonal socket-head bolts,
• wherein the insulating layer is provided at outer sides of the flange and the pressure-bearing shell,
• wherein the axial pressure piston extends through a center hole at a top of the pressure-bearing shell into the loading main body,
• wherein the sample base is disposed on the flange, and is sealed with the flange via a seal ring,
• wherein the liquid inflow loading pipe and the exhaust pipe are connected to holes in the flange through the insulating layer and communicated with a confining pressure loading space inside the pressure-bearing shell,
• wherein the freezing system comprises:
• a circumferential freezing liquid circulation channel;
• a circumferential freezing liquid inflow pipe;
• a circumferential freezing liquid outflow pipe;
• a base freezing liquid circulation channel;
• a base freezing liquid inflow pipe;
• a base freezing liquid outflow pipe;
• and
• a dissoluble shell,
• wherein the circumferential freezing liquid circulation channel is disposed inside an outer wall of the pressure-bearing shell, a top end thereof is connected with the circumferential freezing liquid outflow pipe, and a bottom end thereof is connected with the circumferential freezing liquid inflow pipe,
• wherein the base freezing liquid circulation channel is disposed at a bottom end of the sample base,
• wherein the base freezing liquid inflow pipe and the base freezing liquid outflow pipe are disposed inside the flange, respectively, and communicated with the base freezing liquid circulation channel,
• wherein the dissoluble shell is disposed above the sample base in a same axial line as the axial pressure piston, and an inner surface thereof tightly abuts against an outer surface of a latex film,
• wherein the dissoluble shell is in a solid state initially, gradually dissolved by a hydraulic solvent during a test process, and loses a lateral confinement efficacy after a sample turns into a solid state completely,
• wherein the sample test system comprises:
• the sample;
• a pressing head;
• a latex film;
• a serial of axial optical fiber sensors;
• and
• a serial of circumferential optical fiber sensors,
• wherein the pressing head is disposed at a bottom end of the axial pressure piston,
• wherein the sample is disposed between the pressing head and the sample base,
• wherein the latex film is wrapped on an outer side of the sample and sealed with outer sides of the pressing head and the sample base at a top end and a bottom end thereof by first seal rings, respectively,
• wherein the latex film is configured to isolate the sample from the hydraulic solvent after the dissoluble shell is dissolved to ensure that the sample cannot contact the hydraulic solvent, and
• wherein the serial of axial optical fiber sensors and the serial of circumferential optical fiber sensors are preset at a central axial line and a central circumferential line of the sample, respectively, and are led out through the sample base and the flange.