Abstract:The valley disaster chain has recently attracted the attention of academics, which is also a huge challenge in the construction and operation of the Sichuan-Tibet railway transportation corridor. This research gives the definition and components of the valley disaster chains. By review valley disaster chain events that have occurred, the characteristics of the valley disaster chain were summarized, and their evolution models were summarized. The key factors that affecting the valley disaster chain were also discussed. Then, the risk assessment system, prevention, and control countermeasures of the valley disaster chain were proposed. The conclusions were obtained as follows: 1) The valley disaster chain is composed of potential disasters, primary disasters, secondary disasters (or series), and disaster-bearing bodies. Their typical characteristics were summarized as time continuity, spatial continuity, causality, and chain evolution. Based on the primary disasters, the valley disaster chain can be divided into 3 categories and 11 sub-categories, including the landslide disaster chains, the debris flow disaster chains, and the glacial lake disaster chains, which can be formed by a combination of three key processes (collapse/landslide-clastic flow/debris flow, landslide/debris flow blocking the river, and dammed/glacial lake outburst). 2) The formation of the valley disaster chain includes two modes. One is that the physical and mechanical properties of the primary disaster mass changed during movement to form secondary disasters, the other is that the primary disaster body changes the boundary of the secondary disaster body that induces secondary disasters. 3) The risk assessment of the valley disaster chain should pay attention to both the initiation mechanism of the primary disaster and the chain generation mechanism of the secondary disasters. It is suggested to strengthen the identification accuracy of the source of the potential disaster, develop the scientific understanding of the disaster transformation process, and quantify the disaster transformation mechanisms and critical conditions, establish a numerical simulation and evaluation method for the valley disaster chain, and carry out the evolution process and risk assessment of the valley disaster chain under future scenarios; 4) The prevention and control of the valley disaster chain is still in its infancy and should be improved based on the scientific understanding of the disaster chain. A comprehensive system for early identification, monitoring and early warning, simulation evaluation, emergency response, engineering governance, emergency avoidance, and risk management of the valley disaster chain is needed in the future.