Located at the end of the mall connecting Buckingham Palace with Trafalgar Square, the Admiralty Arch is one of London’s most iconic buildings. The structure incorporates three archways with roadways that provide vehicle and pedestrian access to the area. As part of redevelopment efforts to convert this Grade 1 listed building into a Waldorf Astoria Hotel, residences, and private members club WSP was engaged to provide structural and geotechnical engineering for two new basements, housing a ballroom, spa, and swimming pool. The project presented significant design challenges to accommodate two underground tunnels amid the clay soil, as well as requiring that the roads remain open to traffic throughout construction.
Because the basements are located above two London underground tunnels, the team designed a box-in-box system to provide acoustic isolation, performing a ground movement assessment and understand the soil composition. The team also conducted iterative modeling and analysis. To ensure that the site remained open throughout construction, the team implemented a phased top-down construction methodology and created 3D models for each construction phase. WSP’s use of open modeling and simulation applications facilitated effective collaboration and visual communication across the multiple design disciplines, which helped streamline the obtaining of statutory approvals.
By implementing modeling and analysis, WSP saved 25% in structural design time, enabling the team to complete the design phase one month ahead of schedule. The team was able to control tunnel movement and provide the required tension piles to balance the loads effectively and prevent tunnel deformation.
WSP relied on Bentley’s PLAXIS for geotechnical engineering to conduct finite element analysis and predict movements and forces along the tunnels. Using Bentley’s RAM to perform iterative modeling allowed WSP to determine the most efficient solution for the basement slabs and raft foundations. The structural modeling and analysis software helped achieve the most economical design within the tight deadlines. Leveraging Bentley’s flexible, interoperable applications WSP was able to clearly communicate and coordinate design process and intent, as well as effectively implement a phased top-down construction methodology.
Project Playbook: PLAXIS, RAM