Design and Practice of Deep Foundation Pits for Large Storage Ponds in Complex Environments

Storage ponds (storm detention ponds) are an important part of sponge city construction, and the construction process involves deep and large pit excavation in a complex and sensitive environment. Combined with a large storage pond pit engineering design and practice process, in this study, the complex environment of the design of the large storage pond pit method has been explored, using the field measurement data to test the support design of the deformation control effect and to summarize the practice of the key, difficult points of treatment measures. The results show that the procedure adopted in this project is a successful practice for using the pit characteristics, and the special treatment carried out for addressing the difficult points can effectively control the deformation, thus achieving waterproofing and deformation requirements of large-capacity water storage ponds. The design of the support is very effective in controlling the duration and deformation. The cover-cut excavation method, in combination with the support system, is highly effective in deformation control, whereas the open-cut excavation method is more likely to shorten the duration. However, there is an uncertainty in the deformation control during the removal of temporary structures in this method. The deformation characteristics of the pit enclosure and the surrounding ground surface are within the design requirements. The horizontal displacement of the wall and the surrounding settlement are mainly developed during the stage of dismantling the temporary support structure after excavating the first basement level and during the construction of the first and second slabs. The other stages benefit from the strong integrity of the support system, which can efficiently control the deformation. The treatment measures, support types, and component connection methods summarized in this article can provide a reference for the construction of similar underground storage ponds.