Temperature-controllable large-size geotechnique true triaxial multi-field coupling test system and test method

A test method based on a temperature-controllable large-size geotechnique true triaxial multi-field coupling test system that comprises:

• a host loading mechanism;
• a deformable large-size soil box;
• an independent three-dimensional loading unit;
• a refrigeration, water and salt supplementation unit;
• and
• a soil-water-ice-salt change monitoring unit;
• the deformable large-size soil box being arranged on the host loading mechanism;
• the independent three-dimensional loading unit, the refrigeration, water and salt supplementation unit, and the soil-water-ice-salt change monitoring unit being all connected with the deformable large-size soil box to respectively correspondingly apply stress to the deformable large-size soil box, supplement refrigeration as well as water and salt, and monitor soil-water-ice-salt changes;
• the host loading mechanism comprising a carrier base, a vertical loading framework, and a horizontal loading framework;
• the carrier base comprising a carrier table located below the vertical loading framework and a rail seat extending in a horizontal direction of the carrier table;
• the horizontal loading framework comprising a workbench, a lateral reaction frame, and a moving lifting wheel being disposed below the workbench;
• the lateral reaction frame being disposed on the workbench through a lateral pressure vertical column;
• and the deformable large-size soil box being disposed on the workbench and being surrounded by the lateral reaction frame;
• the deformable large-size soil box comprising a bottom plate, soil box side plates, a soil box horizontal deformation limiting device and a normal loading plate;
• a water supply and drainage trough being arranged on an upper surface of the bottom plate;
• a water permeation plate being arranged on the water supply and drainage trough;
• a lateral sliding device being also arranged on an outer side of each of the soil box side plates;
• a lateral oil cylinder being fixedly provided on the lateral reaction frame;
• the lateral oil cylinder passing through the lateral reaction frame and being connected with the lateral sliding device;
• and the lateral oil cylinder sliding along the lateral sliding device in a deformation process of the deformable large-size soil box;
• the test method comprising:
• pulling out the workbench, and assembling the deformable large-size soil box;
• filling the deformable large-size soil box with soil layer by layer, arranging monitoring sensors included in a water-ice-salt change monitoring module of soil-water-ice-salt change monitoring unit in an environmental soil region of the soil, completing filling of soil test samples, and arranging the water-ice-salt change monitoring module and a soil structure change monitoring module included in the soil-water-ice-salt change monitoring unit;
• resetting the workbench to the carrier table, arranging a hollow square fender included in a normal power loading module of the independent three-dimensional loading unit, and arranging the normal loading plate in the hollow square fender;
• connecting the refrigeration, water and salt supplementation unit, connecting a refrigeration equipment included in the refrigeration, water and salt supplementation unit to a cooling pipe included in a refrigeration module of the refrigeration, water and salt supplementation unit in the normal loading plate through a circulating pipe to realize apply a temperature load to a top of the soil test sample, and arranging a water and salt supplementation module included in the refrigeration, water and salt supplementation unit at a bottom of the bottom plate to apply water and salt to a bottom of the soil;
• and
• arranging a horizontal power loading module included in the independent three-dimensional loading unit and the normal power loading module to load three stresses in unequal directions.