Monitoring and performance of deep basement excavation at Royal Sussex County Hospital, Brighton

The Royal Sussex County Hospital development is to include the construction of numerous hospital buildings and will be developed in three phases. This paper reports on the works related to the Phase 1 development of this project. This phase of development comprises the construction of a contiguous bored pile retaining wall to support a 2 to 4 level basement followed by construction of an up to 10 storey superstructure. Due to the topographical nature of the site, a two level basement at the south and four level basement at the north is to be constructed, with a maximum excavation depth of 19.5 m. The ground conditions at the site comprise Made Ground underlain by White Chalk Subgroup. The results reported in this paper are data gained from an on-going project. At the time of writing this paper, the basement excavation has been completed to formation level in the northwestern corner, along the western wall and in the southwestern corner of the site. Although the full basement excavation is not completed, the current data gained indicates that a single level temporary prop is sufficient to limit the impact on the existing buildings. The wall movements and load cell monitoring recorded indicate that the ground response is stiffer than the design values used in the design assumption.