【正文】 ld be met: Cracks in the ground floor of building structures to deal with prevention and treatment. Analysis: (1) Design factors: emphasis on the general design of underground construction works vertical wall panels of the reinforced structure and intensity, the level of neglect of horizontal reinforcement cracking strength. Crosssection of the wall structure due to the particle stress is nonuniform shrinkage stress and thermal stress of concrete efforts to achieve the ultimate tensile strength, caused by the plastic deformation and fracture。s cold climate, so in large cities, the development of underground mercial center of the city of Montreal has a few underground mercial center even as a construction area of 810,000 square meters, forming an underground city. In addition, industrialized countries also paid attention to the protection of underground construction to play the traditional style of the city to improve the urban environment, urban space, etc. to expand the positive role played by. For example, the city of Nagoya, Japan in conjunction with urban roads alteration, in the ground layout of the mercial street and parking lot, stay out of the ground in addition to the necessary pedestrians, carriageway, in the central part of the park into a largescale city center. Other factors, such as Tokyo, Osaka and other places are also provided with the underground business street. Another example is the University of the United States a number of historical buildings and structures in order to preserve the unity of style and ease tension in the land, the construction of a number of underground construction, such as library, gymnasium, teaching Museum (Figure 2), achieving good results. These facts reflect the tiefbau increasingly wide range of applications. Underground construction of the type of underground construction can be classified according to the functions of military, civil, air works, industry, transport and munications, storage and other buildings, and underground utilities. For example: in the construction of military fortifications can be used for shooting, observation of construction, shelter construction, etc.), in civil construction, including residential buildings, public buildings, a variety of civil air defense engineering, industrial construction, transportation and munication construction, warehouse construction, as well as the types of underground utilities, such as underground water plant, solid or liquid waste 5 treatment plant, pipeline and other corridors. Several features of both largescale underground construction known as the underground plex. Tiefbau classified according to construction method, there are two types of open excavation and mining. Open excavation pletely backfilled after construction, the above did not build any buildings, known as singlebuilt underground construction。 in the mountains, rock fissures should be based on the volume of water and gushing location, organization of the underground drainage system construction and attention to surface water flow and the excretion of mountain torrents. ② to ensure the necessary protection. Although the underground construction itself with varying degrees of protection against all kinds of weapons, but the air defense of the military construction and engineering, but also the protection levels in accordance with the provisions of the various effects of different weapons, to conduct a prehensive protection of the design, layout of the various protection facilities, building structures and protection facilities, as well as a variety of holes, I have the appropriate protection, we should focus on building entrances and exits to ensure the security of the site. ③ the creation of an appropriate internal environment. Underground space in the internal environment, including air temperature, humidity, cleanliness, noise intensity, the illumination lights, interior colors and so on. Appropriate depends mainly on improving the quality of air in the ventilation design to ensure。 doped admixtures, such as poor quality. As a result of modity highstrength grade concrete, cement, and water consumption, and hydration heat caused by high temperature, when the environmental temperature significantly decreased the role of the temperature difference, the new casting of the linear expansion coefficient of concrete! c = 10 106 / ℃ , when the contraction in the cooling caused by tensile stress increases. Concrete wall surface area larger than the shrinkage stress generated internally binding, the formation of shrinkage, shrinkage, temperature difference between the integrated stress, ultimate tensile strength greater than concrete and cracks。 13 (6) the use of thinlayer approach for irrigation, to ensure that the uniform density of concrete, to take the conservation of heat storage method, in order to reduce the temperature difference between inside and outside elements, and strictly control the cooling rate of ℃ / d, for the concrete conditions of the creation of stress relaxation, is to prevent shrinkage cracks in concrete structures, one of the main measures。s own utility system and the status of directburied 15 pipeline to make it to the layout and use of multifunction integrated pipeline corridor direction. To this end, calls for unity under the guidance of the overall urban planning, the development of urban underground space development and utilization of prehensive planning, and the same on the ground to unify urban development planning. 16 地下建筑結(jié)構(gòu) 建造在巖層或土層中的建筑。地下建筑也有缺點(diǎn)，如 建筑成本高，施工復(fù)雜等。估計(jì)中國目前仍有