HARDING PRIZE COMPETITION 2024 | BTS


Left, figure 9:


Examples of 3D models of (left) TSC adit and shaft base, (right) segmental tunnel


PHOTO CREDIT (TOP): ADDA-BIM


In the HPC onshore works, multiple strike cubes


per pour have typically been relied upon to understand the strength gain within a concrete pour over time. As they are more exposed to external influences, strike cubes can behave variably compared to the concrete pours they are taken from, which would be significantly greater in volume and thickness, and therefore thermally act differently. For use on the TSC, to improve quality assurance,


reliability, and to reduce the required time before striking of formwork, a constant in-situ monitoring system (maturity modelling) is being developed by BB with support from myself and the Jacobs materials team. This system also provides safety benefits as it reduces the need for workers to prepare and retrieve strike cubes.


As the SCL surface is rough, it creates high restraint


between at the interface of the PW concrete as it cures. This can lead to non-compliant cracking which would need repair. When designing the TSC PW, the latest crack control


guidance has been followed in accordance with CIRIA C766.12


control reinforcement (which may only be partially required for structural purposes) with limiting that likelihood of non-conformances. Following my participation in a training session


with the author of CIRIA C766, I investigated means of reducing early thermal cracking that was occurring within the onshore tunnels. This led to the installation of a debonding layer onto the SCL (see Figure 10).


May 2024 | 19 This has required balancing the provision of crack


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41