地下水的动态变化是诱发土质滑坡发生的重要因素。以三峡库区典型厚层土质滑坡——谭家湾滑坡为例,利用多年积累的全球导航卫星系统(GNSS)地表位移、地下水及降雨监测数据,结合多次现场调查,研究降雨条件下导致地下水水位动态变化诱发土质滑坡的变形机制。研究结果表明:谭家湾滑坡变形集中在中前部与左侧,且与降雨事件密切相关,前期降雨量决定坡体变形对前期单次强降雨的响应程度;此外,地下水位与降雨入渗有显著时空相关性,水位上升速率受前期和期间降雨强度影响;坡体变形的趋势受到水位动态变化的控制,同时坡体稳定性也受地下水位峰值持续时间的制约;降雨入渗后引起地下水动态迁移有2条路径,其中经路径AB形成的动水压力结合地形条件,促使了Ⅰ-1滑体的变形。研究成果可为降雨条件下土质滑坡变形机理、早期识别及预警等研究提供理论依据。

[Objective] Dynamic groundwater changes represent one of the key controlling factors in the initiation of soil landslides. Investigating their response characteristics and mechanisms under rainfall is crucial for understanding landslide stability and evolutionary processes. [Methods] Taking the typical thick soil landslide—Tanjiawan landslide—in the Three Gorges Reservoir area as the research subject, this study systematically analysed the influence mechanism of groundwater level dynamics under rainfall by relying on multi-year continuous high-precision GNSS surface displacement data, automated groundwater level monitoring data, regional rainfall records, and information obtained from repeated field geological surveys on landslide geological structure, sliding mass structure characteristics, and groundwater recharge and discharge conditions. [Results] Deformation of the Tanjiawan landslide was concentrated in the mid-front and left-side areas and was closely related to rainfall events. Antecedent cumulative rainfall, to a certain extent, determined the slope's deformation response to a subsequent single heavy rainfall event. When cumulative rainfall was sufficient, even moderate single rainfall intensity may induce significant deformation. Groundwater level changes and rainfall infiltration showed distinct spatiotemporal correlation. The rate of water level rise was influenced by rainfall infiltration conditions and jointly controlled by both the antecedent effect and the concurrent effect of rainfall intensity. After rainfall infiltration, dynamic groundwater migration followed two main paths: one along route AB rapidly converged on the frontal area, generating strong hydrodynamic pressure; the other migrated slowly within the sliding mass, producing a cumulative effect on overall water content and pore water pressure. The hydrodynamic pressure generated along route AB, when coupled with local topographic conditions, directly drove deformation of the I-1 sliding mass, triggering local accelerated deformation or even failure. [Conclusions] Slope deformation trends are significantly controlled by dynamic groundwater changes, whereas slope stability is, to a certain extent, constrained by the duration of peak groundwater level. Prolonged high water levels markedly reduce slope stability. Moreover, monitoring data shows a certain lag between groundwater level rise and slope deformation rate, a characteristic that provides important reference value for early identification and early warning of thick soil landslides. This study provides a theoretical basis for research on the deformation mechanism, early identification, and early warning of soil landslides under rainfall conditions.