Abstract: Soil particles in cold regions are deposited and arranged along the dominant direction due to gravity, forming transversely isotropic frozen soils. Without considering the effect of the deposition angle between the deposition direction and the load direction, the deformation characteristics and bearing capacity of the actual geotechnical engineering in cold regions may be misestimated. However, the effect of deposition angle on the mechanical properties of frozen soil has not been explored in the existing literature. In response to this problem, the uniaxial compressive tests under different temperature conditions were carried out in this paper to examine the effect of deposition angle on the mechanical behaviors of frozen soil. With the developed sample preparation mould, frozen soil samples with four different deposition angles δ (δ = 0º, 30º, 60º and 90º) were prepared. Uniaxial compression tests on these frozen soil samples were carried out at four different temperature conditions T (T = −5, −10, −15 ℃ and −20 ℃). The significant effects of T and δ  on deformation mode, failure behaviors and uniaxial compressive strength of frozen soil are analyzed. The uniaxial compressive stress-strain curves of frozen soil at certain T and δ are normalized, and the slope variation rule of the softened section is also analyzed. According to the above analysis, the deformation modes of the frozen soil under the effect of T andδ  are divided into three deformation modes, i.e., I, II and III. According to the test results, it can be observed that as T decreases and δ  tends to 60º, the deformation mode of frozen soil tends to transition from deformation mode I to deformation mode III, and the failure model tends to transition from the expansion failure mode with the X-shaped shear band to the single shear plane failure mode with a smaller failure range. The uniaxial compressive strength of frozen soil increases with the decrease of T, and shows a trend of first decreasing and then increasing with the increase of δ .

Key words: transversely isotropy, deposition angle, frozen soil, uniaxial compression test, mechanical properties