Development laws of geological hazards along urban highway in Southwest China and countermeasures for prevention and control

China is a mountainous country with highly developed road geologic hazards, which pose a great threat to the construction and operation of highways, bridges, and tunnels and to the safety of people and property. This paper discussed the types, basic features, formation, and prevention conditions of road geologic hazards in China based on field research and study data collected thus far. The study considered an urban area of a city in southwest China as the center and a geological field investigation was performed over a total of 282 ​km on three important lifeline projects. The results show: Types of geologic hazards along the highways are mainly avalanches, debris flows, and landslides, respectively. Among them, the landslips are mainly distributed along the roads, with slip, dumping, and wrong break types as the main ones; the debris flows are widely distributed, mainly concentrated in the river valleys; and the unstable slopes are relatively few in number. Geological disasters are characterized by large-scale and concentrated triggering in time and space, and a single disaster can easily trigger other disasters, thus forming a chain of disasters. Neotectonic movement, seismic activity, topography, climatic conditions, stratigraphic lithology, and human activities are important factors leading to geologic hazards in the study area. This study is of great practical significance for reducing the occurrence of roadbed diseases and prolonging the service life of highways.