A bomb shelter refers to a cave used to defend against enemy air strikes and reduce losses. It is usually used to store food and military supplies. Storage rooms are mostly in the basement, which is easy to hide. According to the classification of structural forms, civil air defense engineering can be divided into tunnel engineering, tunnel engineering, piling engineering and tunnel engineering. Tunnel engineering Tunnel engineering is a kind of underground excavation engineering, in which most of the ground bodies are located below the lowest entrance and exit, and most of them are built on the flat ground. Mine engineering is an underground excavation engineering with most of the ground higher than the lowest entrance and exit, which is mostly built in mountainous areas or hilly areas.

Accumulation engineering Accumulation engineering refers to the engineering in which most buildings are located above the original surface and covered by backfill. Excavation Engineering Excavation engineering is a project constructed by cut and cover, and most buildings are located below the original surface, including single buildings and ancillary buildings. Generally, there is no directly connected building on the upper part of a single building project; There is a physical building on the upper part of the affiliated project, also called the air defense basement. Early civil air defense projects were mainly tunnel projects. Since 1980s, the civil air defense construction has carried out a strategic change in guiding ideology, emphasizing the combination of peacetime and wartime to serve the economic construction and urban construction. Most of the new civil air defense projects are excavated, with good location and high quality. At the same time, the decoration level of some civil air defense projects is generally higher than that of ground buildings, so as to attract people to the underground and provide people with a relatively comfortable environment.

Classification of wartime functions According to different wartime functions, civil air defense communication engineering can be divided into command communication engineering, medical rescue engineering, air defense professional team engineering, shelter engineering and other auxiliary engineering. Commander communication engineering Communication command engineering refers to all levels of civil air defense command institutions and their supporting projects such as communication, power supply and water supply. Medical rescue engineering medical team is the general name of underground central hospital, underground emergency hospital and medical rescue station that provides medical team in wartime; The specialized civil air defense team for air raid prevention refers to the professional teams of civil air defense rescue, fire fighting, chemical defense, communication, transportation, public security and other corresponding auxiliary projects at all levels;

Personnel shelter project refers to party, government and military organs, organizations, enterprises and institutions at all levels, residential shelter projects and their ancillary projects, and refers to underground hospitals, various warehouses, production sites, evacuation motor roads, communication channels, areas, supplies and nuclear monitoring stations. According to the usual purposes, civil air defense projects are divided into underground hotels (guest houses), underground shopping malls (shops), underground restaurants (restaurants, grocery stores, bars and cafes) and underground cultural and artistic activities (including dance halls, cinemas, exhibition halls, video halls, karaoke halls, shooting ranges, playgrounds, billiards rooms and swimming pools). ), underground classroom, office, hall (.