Abstract: In the area of geotechnical engineering practice, the deep excavation engineering requires complicated and comprehensive approach for a better solution. A deep excavation project, from the initial selectin of the method of support of excavation to the final implementation and construction of supporting structures, many factors could potentially affect its success. These factors include, but not limit to, feasibility of the supporting structures, construction safety of cost considerations, adjacent environmental conditions, subsurface conditions and construction equipment loadings. This paper presents an urban deep excavation supporting design in the soft soil area case history. Factors and challenges in the deep excavation supporting structure design is also introduced. The project was surrounded by the municipal streets, existing building structures and a gas station and the excavation support design utilized double-row soldier pile plus strengthening in the passive soil zone method as well as soldier pile lagging plus internal support method. The localized area reinforcement design and minor design adjustment due to the change of subsurface soil conditions are also introduced in the paper.

Key words: deep excavation engineering, soft soil area, support of excavation design, complex environment