To investigate the unloading mechanical properties of deeply buried silty soil in dam foundation cover layers, a series of consolidated drained triaxial compression tests along multi-stage loading-unloading path were performed on both undisturbed samples (including horizontally and vertically oriented samples) and remolded samples. The test results demonstrate that: (1) the vertically oriented soil samples exhibit strain softening under low confining pressures (100, 200, and 400 kPa), transitioning to strain hardening at high confining pressures (800 and 1600 kPa). In contrast, the horizontally oriented specimens consistently exhibit strain softening across all confining pressures, whereas the remolded samples display strain hardening under all confining conditions; (2) the strength of vertically oriented soil specimens is significantly higher than that of horizontally oriented specimens, ranging from 1.18 to 1.43 times greater. Remolded samples, however, remolded samples are slightly weaker than horizontally oriented specimens under low confining pressures (100, 200, and 400 kPa), while at high confining pressures (800 and 1600 kPa), their strength approaches that of horizontally oriented specimens; (3) the deeply buried silty soil also exhibits pronounced unloading-induced volume contraction characteristics, which increase with the initial axial strain at the beginning of unloading and diminish as confining pressure increases; (4) the unloading modulus is obviously higher than the initial loading modulus, with the ratio of the unloading modulus to the initial loading modulus ranging from 1.4 to 3.6. This ratio increases with increasing confining pressure but decreases with increasing axial strain at the onset of unloading.