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

The invention relates to a method for testing a three-dimensional thermal expansion coefficient of a geotechnical material under a three-dimensional stress condition. The method comprises the following steps of: preparing a geotechnical material sample and a quartzite standard sample; respectively carrying out three-way pressurization on the geotechnical material sample and the quartzite standardsample through 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 systemto obtain three-way linear expansion amounts of the geotechnical material sample and the quartzite standard sample under a three-dimensional stress condition; and calculating the three-dimensional linear expansion coefficient of the geotechnical material sample under the three-dimensional stress condition by using a determination formula according to the three-dimensional linear expansion amountsof the geotechnical materi