There has been a big focus on Geotechnics this week. Designing the foundations has not been an easy ride, to say the least. Network Rail imposes restrictions on CFA piling in the land between the railways tracks and the proposed HS2 tunnel passing close under the north block dismisses the option of using piles here altogether. The final design calculations have been based on combination of raft, bored pile and CFA pile foundations, as shown in the elevation view below.
A three-storey basement has been designed under the north block to increase the founding depth so that the raft foundations lie in the stiffer London Clay layer. The opportunity to use this extra space for car parking and storage purposes has been fully explored, helping to minimise the vertical height of the north building.
As trains will pass under the development, there is a low probability but high impact risk of train derailment. Black swan alert. To treat this hazard, the columns within the width of the railway tracks have been designed to withstand train impact in the event of derailment, with the help of a lot of steel reinforcement.
To complement the trauma centre, a helipad was requested by the clients in our previous critical session. Planning permission is required for helipads used more than 28 days per year. This would inevitably cause backlash from local residents so it has been decided that, as the Royal London Hospital is so close and has a helipad running well within capacity, the helipad at this site will only be used in rare extreme events. The helipad will be located on the rooftop of the north block, with a lift straight down to the trauma unit in A&E.
The south block will house The Admin component (see Week 3), containing installations such as the doctors’ offices, educational facilities, goods delivery access and waste storage. Floor plans for the south building and the tower have been completed.
The clients were happy with the final design we presented at the final critical session and only a few very minor changes have to be made, leaving us well-placed to complete the final report and poster next week. Can’t wait…