The characteristics of geostructures of urban underground space in coastal bedrock area of Qingdao

It is urgent to develop the underground space efficiently and reasonably for the large-scale urban construction in Qingdao City, Shandong, China. The clear understanding of the geostructural characteristics of underground space in the city and providing a more scientific and reliable basis for rational planning and development of the urban underground space are important to meet the needs of urban sustainable development. Based on the data of urban geological survey and geoengineering investigation, this paper summarizes the regional structure, geomorphology, fractures, rock and soil structure and geoengineering conditions and introduces the geostructural characteristics of the underground space in detail for the city. Results show that the bedrocks strictly controlled the rock and soil structure and affects the distribution of quaternary sediments in Qingdao. The local rock masses can be divided into four types, and the Quaternary cap strata can be divided into 12 layers. The geo-structural model of Qingdao constructed by available data shows that the top buried depth of the middle-lower crust is about 12 km, and the key upper layer of the underground space development ranges from 0 to 60 m. The 3D geoengineering model of the key layer of the surface shows clearly the geoengineering structures, which is conducive to improving the overall understanding of the geological background of Qingdao and providing a scientific basis for the subsequent underground space development and construction.