Strength criterion for intact loess under high-temperature action

Geothermal heating and cooling is a new type of building energy-saving technology that utilizes surface geothermal energy, which causes temperature changes in the surrounding geotechnical bodies when it works, and affects the strength characteristics of loess when it is applied in loess areas. To investigate the change in the strength of intact loess under the effect of temperature, this study uses loess in the Xi'an area of China as the main research object and conducts consolidated undrained triaxial shear tests on intact loess at four different temperatures (5 ℃, 20 ℃, 50 ℃ and 70 ℃) to analyze the change law of shear strength of intact loess specimens under varying temperatures. The results show that the stress‒strain curves of loess specimens show strain softening under the effect of different temperatures, while the stress‒strain curves of remodeled loess show strain hardening, and the strength of loess gradually decreases with increasing temperature under the same confining pressure. Based on the binary medium modeling of a geotechnical body, the shear sharing ratio is modified by considering the effect of temperature and confining pressure. The variation in the shear sharing ratio with temperature \(T\), confining pressure \(\sigma\), parameter m, and structural yield strength \(\sigma_{s}\) is investigated. The strength criterion of intact loess is modified to establish a strength criterion applicable to intact loess under high temperatures, and the strength criterion is verified by indoor test data, which show that the strength criterion has good applicability to intact loess under high-temperature conditions.