Status and engineering problems of utilization of deep underground space in urban coastal soft soil areas

With the continuous construction and development of cities nowadays, the utilization of medium and shallow underground space has reached a certain scale in many areas and even saturated in some metropolises. Rational development of deep underground space has become an effective way to alleviate the pressure of urban space. The literature review reveals that the development of deep underground space is still at a primary stage, mainly for large-scale traffic facilities and municipal service facilities. According to the further analysis, logistics and storage facilities and special projects should also be considered. Additionally, the majority exploring deep underground space development are the world-class cities, most of which locate in coastal soft soil areas where many engineering problems might be encountered during the construction because of the unique physical and mechanical properties of the soil. Taking Shanghai as an example, based on its typical soil layer and three related cases, several engineering problems are discussed, including confined water in rush, quicksand and piping, soil deformation, ground subsidence, and gas escape. By sorting out the above contents, the development status and engineering problems of deep underground space utilization in coastal soft soil areas are summarized, providing a reference for large-scale development in the future.