Method for testing three-dimensional thermal expansion stress of geotechnical material under three-dimensional stress condition

The invention relates to a method for testing three-dimensional thermal expansion stress of a geotechnical material under a three-dimensional stress condition. The method comprises the following stepsof: preparing a geotechnical material sample and a quartzite standard sample; respectively carrying out three-way pressurization on the geotechnical material sample and the quartzite standard samplethrough a real-time high-temperature true triaxial test system; respectively heating the geotechnical material sample and the quartzite standard sample through a high-temperature control system to obtain three-way linear expansion stress variations of the geotechnical material sample and the quartzite standard sample under a three-dimensional stress condition; and calculating the three-dimensionallinear expansion stress of the geotechnical material sample under the three-dimensional stress condition by using a determination formula according to the three-dimensional linear expansion stress variations of the geotechnica