<p>Frequent human engineering activities on the Qinghai-Tibet Plateau have resulted in widespread shallow landslides that pose serious threats to infrastructure and safety. This study investigates the distribution and failure mechanism of shallow landslides in Jiacha County, taking the Zhaxuecun landslide, which occurred on October 24, 2022, as a representative case. The landslide, with a volume of approximately 6.27 × 10⁴ m³, is a typical shallow landslide in the middle reaches of the Yarlung Zangbo River. Through field investigations, in-situ tests, laboratory experiments, and numerical simulations, the material composition, structural characteristics, degradation of mechanical properties, and failure mechanism were systematically analyzed. Historical deformation identified from Google Earth Pro imagery indicated that slope instability began after highway excavation. In-situ permeability tests showed a high permeability coefficient (297.06&#xa0;m/day) within the landslide. Direct shear tests demonstrated a marked decrease in the shear strength of gravelly soil under saturated conditions, and rebound tests indicated weak anisotropy between bedding and vertical planes. The long-term effects of water and freeze-thaw cycles promoted the formation of fissures and infiltration channels, accelerating slope failure. Numerical simulations revealed the evolution of velocity and energy during sliding. Combined with meteorological data, it is inferred that the deformation of the Zhaxuecun landslide was jointly influenced by excavation, freeze-thaw cycles, and snowmelt. The landslide evolution can be divided into four stages: excavation-induced deformation, long-term freeze-thaw degradation, critical stability formation, and sliding failure. These findings provide insights into the deformation mechanisms of shallow landslides along the Yarlung Zangbo River.</p>