BTS March 2022 Meeting - Design and construction of a cavern in Downtown Los Angeles

Описание: 𝗦𝗽𝗲𝗮𝗸𝗲𝗿 : Carlos Herranz (Tunnel Design Manager - Mott MacDonald)

Los Angeles Metro is constructing a light rail corridor beneath Downtown Los Angeles—The Regional Connector Transit Corridor (RCTC). To provide operational flexibility, RCTC required a track crossover adjacent to one of the stations. Right of way constraints required the crossover be constructed at relatively shallow depth using Sequential Excavation Methods (SEM), resulting in what is believed to be the largest mined cross section in Los Angeles. Challenges faced for the SEM cavern design and construction included strict limits for tunnelling induced displacements in surrounding structures and high seismic design loads with 2,500 year return periods. This presentation describes the design approach of the SEM cavern, with an emphasis on the seismic analysis, as well as the actual conditions faced during construction.

The lecture presents some small steps forwards in developing sustainable sprayed concrete tunnels, not just purely focused on the concrete material technology that is often the only item under scrutiny, but a more holistic view covering concept design, spraying equipment and smart digital tools. The lecture also highlights the needed behaviours to support the adoption of more low carbon solutions, where in the speakers view, the active involvement with all stakeholders to drive change is a pre-requisite, but certainly with strong direction and leadership from client teams who inevitably benefit in the long run.

The lecture will illustrate by example how we currently compare to another “advanced” tunnelling nation such as Norway who have stepped ahead in this more sustainable tunnelling quest.

Disclaimer : All opinions and views expressed by the speakers, including those participating in the Q&A, are their own and do not necessarily represent the views of the British Tunnelling Society or the Institution of Civil Engineers.