One North Quay: Case Study transcript

My name is John McDade. I’m the Senior Project Manager for Kilnbridge on this project, One North Quay, for Canary Wharf Contractors. My role is overseeing the complete reinforced concrete package.

The structure at One North Quay is an RC structure. The use will be as a life science building, 60% for laboratories. The original bulk excavation was to get the core cap built so that slip form could get away, get the props into the south, and that allowed us to bulk excavate to the south. As we advanced, that allowed us to get the concrete props into the north and progress the bulk excavation in the north as well.

When we started our bulk excavation, we came across a lot of problems in the ground, as you normally do. We ended up having to change our propping sequence, which had to be agreed with the designers.

My name is Geda. I’m a Temporary Design Engineer.
My name is Cristiana, and I’m a Senior Engineer with Conquip.

My role within Conquip is to design safe, efficient, and cost-effective temporary works solutions. This project was split into two elevations, north and south. I was the propping designer for the north elevation.

The main challenges on this side of the wall were mainly the deflections. We had the thick wall start moving quite a lot. Concrete had very restrictive deflections to work with. We had to move around props, work with the waling beam capacity, and manage all of that to achieve the maximum allowable deflections.

Conquip provided the temporary propping design that perfectly fits in with the project plan, construction sequence, and timings to ensure construction runs smoothly. The temporary propping system includes props, walers and ancillary items like gallows brackets, shear keys, and shear stops.

The other challenge is the raking nature of the props. We have massive uplift forces which we had to resist and transmit to the pile wall. That meant we had to slightly adjust our gallows brackets to receive those forces.

There was a requirement to have sufficient clearance around the core area. To achieve this, we developed a two-stage propping solution. The first stage enables the construction of the basement wall. Once this has been cast, stage two propping provides the required clearance for the core area to be constructed without obstruction.

The main challenge was to limit the deflection. There was a strict deflection requirement for this job. We used a double waler where necessary to achieve this.

In true collaboration with Conquip, we managed to get that over the line and it saved us a lot of time.

Our experience working with Conquip has been very positive. Even from the very start, before we awarded the project, they were very engaging and helped us with ideas and overcome challenges in incorporating the temporary works into the permanent works.

When the first whalers and props arrived, the project manager came down to site. They ran through everything with our team and were on call anytime we were installing props.

Kilnbridge was great from the beginning. Before starting the detailed design, we met, discussed expectations, and clarified all queries. It was very easy and efficient, allowing us to deliver a fast design with minimal design changes.