Elasto-plastic behaviour of frozen soil subjected to long-term low-level repeated loading, Part I: Experimental investigation

•A series of long-term repeated triaxial tests on frozen soils are conducted.•The amount and direction of accumulated strain of frozen soils are studied.•The influences of stress measures and strength on accumulation are investigated.•Variations in accumulated direction as the increasing loading cycles are significant.•The evolution and influence factors of elastic behaviour are presented.

The elasto-plastic behaviour of frozen soil subjected to long-term low-level repeated loading is frequently characterized by resilient modulus and accumulated strain, which are significant factors for construction in cold regions. This paper presents an experimental investigation and test results in which accumulated behaviour, including the amount and direction of accumulated strain, is shown to be significantly affected by the initial stress state, repeated stress amplitude and frozen soil strength. Variations in the accumulated direction with increasing numbers of repeated loading cycles cannot be neglected. The resilient modulus, including the shear and bulk components, increases with the accumulation of plastic strain and is clearly dependent on the initial mean stress. These innovative discoveries may help elucidate the properties of frozen soil influenced by long-term low-level vibrations. Furthermore, this work will provide important data for the development of a constitutive model of frozen soil under long-term low-level repeated loading.