Study on the Humidification Deformation Characteristics of Undisturbed Loess under Cyclic Loading

A series of dynamic triaxial tests were carried out for the undisturbed loess samples to investigate the deformation characteristics under cyclic loading during the process of humidification. The results indicated that the dynamic stress-strain relationship under different humidification water content and confining pressure conform to the Hardin Drnevich hyperbolic model. The dynamic strain increases with the humidification water content increasing. The curves of dynamic strain and humidification water content are approximately linear when the dynamic stress is small, and the curves are concave when the dynamic stress is large. The dynamic strain increases linearly first and then tend to flatten with the number of vibrations increasing. There is a critical vibration times N_cr on the curve of dynamic strain and vibration times, which is the limit of the curve increasing linearly and tending to be flat. The cumulative dynamic strain of undisturbed loess increases with the humidification water content increasing. The main reason for the cumulative dynamic strain increasing is that the soluble salts between soil particles are dissolved by water, and the loess soil structure is damaged. The process of humidification has little effect on the amount of energy dissipated in the same vibration cycle. With the humidification water content and dynamic stress increasing, the distance between the two vertices of the hysteretic loop is lengthened, and its area is gradually increasing. This study had certain guiding significance for controlling the humidification deformation of undisturbed loess foundation under cyclic loading.