[Objective] Against the backdrop of global climate warming and frequent heavy rainfall events, the risk of landslide disasters in high-altitude mountainous areas is increasing due to the combined effects of highly sensitive geological environments and engineering disturbances. However, a systematic understanding of landslide triggering mechanisms and evolutionary processes remains lacking. [Methods] To investigate the deformation response characteristics of high-altitude landslides under rainfall, this study focuses on a typical landslide disturbed by road construction at an altitude of 4, 700 m in Longzi County, Shannan, Tibet. An integrated monitoring system fusing distributed fiber-optic sensing with multi-parameter in-situ monitoring was constructed to obtain meteorological parameters, shallow soil temperature, moisture content, and strain data, as well as deep soil strain data from June 14 to September 30, 2024. [Results] The results indicate that: (1) During rainfall events, the shallow soil exhibits a hydro-thermal-mechanical coupled response mode characterized by rainfall infiltration triggering abrupt changes in moisture content and temperature variations, which subsequently lead to strain compression and gradual rebound recovery. Furthermore, under alternating wet and dry conditions, deformation is intensified by the water-conducting effect of fissures; (2) The deep potential sliding surface (Sliding Surface II) shows significant hysteresis in response to rainfall, displaying a strain accumulation effect under hydraulic disturbance. Its evolution follows a typical path where heavy rainfall infiltration induces a lagged deformation response, followed by stress concentration that culminates in a sudden deformation surge; (3) The summer cyclic process involving heavy rain, continuous rain, drought, and re-rainfall constitutes a highly sensitive window for landslide deformation, during which dynamic monitoring and early warning responses should be strengthened. [Conclusion] The fiber-optic intelligent monitoring system for high-altitude landslides established in this study provides key data support and methodological references for risk identification, mechanism analysis, and engineering prevention and control of landslide disasters in the Qinghai-Tibet Plateau and similar hazardous mountainous areas.
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