# Research Progress in Methods for the Analysis of the Internal Stability of Landslide Dam Soils
###### Abstract  
In this paper, the research progress made in the methods used for assessing the internal stability of landslide dam soils was reviewed. Influence factors such as the gradation of soil and the stress state in the soil in different analysis methods were discussed, as these can provide a reference for the development of more accurate methods to analyze the internal stability of landslide dam soils. It focuses on the evaluation of internal stability based on the characteristic particle size and fine particle content, hydraulic conditions such as the critical hydraulic gradient and critical seepage velocity, and the stress state such as lateral confinement, isotropic compression, and triaxial compression. The characteristic particle size and fine particle content are parameters commonly used to distinguish the types of seepage failure. The critical hydraulic gradient or seepage failure velocity are necessary for a further assessment of the occurrence of seepage failure. The stress state in the soil is a significant influence factor for the internal stability of natural deposited soils. Although various analysis methods are available, the applicability of each method is limited and an analysis method for complex stress states is lacking. Therefore, the further validation and development of existing methods are necessary for landslide dam soils.  
Keywords:landslide dam soils; internal stability; critical hydraulic gradient; seepage failure; stress states +
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high. Some studies have shown that internal erosion caused by seepage is one of the main reasons for landslide dam failures [17; 18; 19; 20]. Therefore, neglecting the issue of internal erosion in landslide dams makes it difficult to understand the true causes of dam breaches or instability, especially when internal erosion is accompanied by overtopping.  
Although existing research on the internal erosion of soils provides a theoretical foundation for understanding the process, most studies do not consider the impact of stress on the internal stability of the soils. In practice, the stress in landslide dams is primarily caused by their own weight, and the stress states in different parts of the dam are different. Ignoring the impact of stress conditions on internal stability may lead to a misunderstanding of the mechanisms of landslide dam instability [21].  
In this paper, influence factors such as the gradation of soil and the stress state in the soil using different analysis methods were discussed, as these can provide a reference for the development of more accurate methods to analyze the internal stability of landslide dam soils. The influence factors, that is, the characteristic particle size, fine particle content, hydraulic conditions such as the critical hydraulic gradient and critical seepage velocity, and the stress state such as lateral confinement, isotropic compression, and triaxial compression, in the assessment of internal stability are summarized. This can provide a reference for the further validation and development of existing methods to assess the internal stability of landslide dam soils.