Abstract
The complex deformation behavior of landslides can be described by the three-stage deformation curve of geotechnical materials, providing an effective phenomenological tool for early warning and prediction. However, to date, the physical mechanism underlying the three-stage deformation of landslides remains unclear, hindering the development of accurate landslide prediction. This paper, based on D'Alembert's principle, restores the dynamic essence of the deformation process prior to landslide instability and establishes a dynamic model for landslide deformation by considering the strain-softening properties of geotechnical materials. This model can express the three-stage deformation characteristics of landslides under constant gravitational force. Through model analysis, the following findings are obtained: (1) The initial stage of landslide deformation can be divided into two sub-stages: initiation and deceleration; the constant-velocity deformation in traditional understanding is not truly constant in velocity, but rather an apparent result of slowly varying velocity; (2) The intrinsic condition for landslide instability under gravitational force is theoretically derived, namely that the driving stress generated by gravity must exceed the ultimate stress of the geotechnical material itself but remain below the peak strength, and this ultimate stress can be directly calculated from shear strength parameters; (3) The theoretical model clarifies that landslide mass and the brittle nature of geotechnical materials are intrinsic factors influencing landslide deformation behavior; (4) Inertial forces drive the landslide system to generate a positive feedback mechanism that controls the nonlinear accelerated deformation of landslides; (5) The strain-softening properties of materials and inertial forces jointly control the three-stage deformation behavior of landslides. The dynamic model for landslide deformation provides a new theoretical and methodological framework for calculating landslide deformation, revealing landslide occurrence mechanisms, and advancing time-forecasting efforts.
Full Text
Research on the Deformation Mechanism and Characteristics of Landslides
XU Qiang1, GUO Pengyu1
1State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059
Abstract
The complex deformation behavior of landslides can be described by the three-stage deformation curve of geomaterials, providing an effective phenomenological tool for early warning and prediction. However, the physical mechanism underlying this three-stage deformation remains unclear, hindering the development of accurate landslide forecasting. This paper reconstructs the dynamic essence of the pre-failure deformation process based on D'Alembert's principle and establishes a dynamic model for landslide deformation that incorporates the strain-softening properties of geomaterials. The model successfully reproduces the three-stage deformation characteristics of landslides under constant gravitational loading.
Model analysis reveals five key findings. First, the initial deformation stage can be subdivided into initiation and deceleration phases, where the traditionally recognized "constant velocity deformation" is not truly constant but rather an apparent phenomenon resulting from slowly varying velocity. Second, the intrinsic condition for landslide instability under gravity is theoretically derived: the driving stress generated by gravity must exceed the material's ultimate stress yet remain below its peak strength, with this ultimate stress being directly calculable from shear strength parameters. Third, the theoretical model demonstrates that landslide mass and the brittle characteristics of geomaterials are intrinsic factors governing deformation behavior. Fourth, inertial forces drive a positive feedback mechanism within the landslide system that controls nonlinear accelerated deformation. Finally, the strain-softening properties of materials and inertial forces jointly control the three-stage deformation behavior. This dynamic model provides a new theoretical and methodological framework for calculating landslide deformation, revealing landslide initiation mechanisms, and advancing time-of-failure prediction.
Keywords: Landslide; Three-stage deformation; Dynamic model; Inertial force; Strain softening