Abstract: The surrounding environment and geological conditions at the proposed project site are complex. The project is adjacent to a subway and an existing deep excavation site. Furthermore, there are ultra-deep foundation excavations with large-span length and large slenderness ratio of the supporting structure sections between two adjacent excavations. The deformation control of the current deep excavation is restrictive, and the technical difficulty is significant. These requirements posed a severe challenge to the foundation excavation supporting designers. The selection of supporting structures is crucial for the success of deep excavation design and construction. This article takes a deep excavation support design of the China Merchants Bank Global Headquarters Building as an example to study the innovative application of the multi-layer strut-type internal support in the supporting design of the ultra-deep excavation with large-span length and large slenderness ratio of the supporting structures. The successful application of this design not only resolves the stiffness problem of the large span length and large slenderness ratio of the supporting structure as well as the transmission and balance of lateral soil pressures, but also effectively controls the deformation of the deep excavation, ensuring the safety of the excavation supporting structure and the surrounding environment.

Key words: Ultra-Deep Excavations, Span Length, Slenderness Ratio, Soil Pressure Transfer and Balance, Supporting Structure Stiffness, Multi-Layer Strut-Type Internal Support