This manuscript is Part 1 of two companion papers that explore a multidisciplinary approach to predict velocity and stability of a large landslide located in the Central Italian Alps: the Ruinon landslide. The area is of high geological interest due to the presence of numerous shallow and deep gravitational instability processes that affect valley flanks, mainly driven by unfavorable morphological conditions and geomechanical properties of rock masses. In this manuscript, a 3D finite element model (FEM) was implemented in order to analyze the stress–strain distribution along the Ruinon rock-slope. Goals are to define the relation between morphological factors, mechanical parameters and the development of irreversible strains. The model was defined based on morphological features and mechanical properties detected along the slope, as well as on piezometric data from the landslide monitoring system. In a first step of the analysis, a static simulation was carried out under dry conditions. Then, a validation process was performed by comparing numerical outputs with geomorphological field observations. Finally, a parametric analysis was carried out where different piezometric level scenarios were evaluated in order to assess the influence of both mechanical parameters and pore pressure on the distribution of high sliding susceptibility areas. By overlaying satellite images with the model outputs, results were shown to accurately reproduce the extent of the slope areas subject to active gravitational instability. Parametric analyses showed a clear relationship between the input factors and the magnitude of strain, while the extension of areas subject to irreversible deformation did not change significantly. Stress distribution and stress–strain relations defined in this article are subsequently introduced in a thermo-hydro-mechanical (THM) numerical model presented in Part 2 of this work, where the evolution of the Ruinon landside is simulated.

本手稿是两篇姊妹篇论文的第 1 部分，这两篇姊妹篇探讨了预测意大利中部阿尔卑斯山大型滑坡（Ruinon 滑坡）速度和稳定性的多学科方法。该地区具有很高的地质意义，因为存在许多影响山谷侧面的浅层和深层重力不稳定过程，主要是由不利的形态条件和岩体地质力学特性驱动的。在本手稿中，采用了 3D 有限元模型 (FEM) 来分析 Ruinon 岩石斜坡上的应力-应变分布。目标是定义形态因素、机械参数和不可逆应变发展之间的关系。该模型是根据沿斜坡检测到的形态特征和力学特性定义的，以及来自滑坡监测系统的测压数据。在分析的第一步中，在干燥条件下进行静态模拟。然后，通过将数值输出与地貌现场观测进行比较来执行验证过程。最后，进行了参数分析，评估了不同的测压水平情景，以评估力学参数和孔隙压力对高滑动敏感性区域分布的影响。通过将卫星图像与模型输出叠加，结果显示可以准确地再现受主动重力不稳定影响的斜坡区域的范围。参数分析显示输入因素和应变大小之间存在明确的关系，而不可逆变形区域的延伸则没有明显变化。本文定义的应力分布和应力-应变关系随后被引入到本工作第 2 部分中提出的热-水-机械 (THM) 数值模型中，该模型模拟了 Ruinon 陆侧的演化。