OWNER:
Midlands Partnership NHS Foundation Trust (MPFT)
ENGINEER:
Couch Consulting Engineers
GENERAL CONTRACTOR:
Key Construction (Birmingham, GB)
MAIN FIGURES:
c.750 Vibro Stone Columns
Project Details
Haywood Hospital operated by the Midlands Partnership NHS Foundation Trust (MPFT) were replacing the existing outpatients building because the building contained Reinforced Autoclaved Aerated Concrete (RAAC) within its roof. There is currently a national programme is underway to remove RAAC from all NHS buildings. The new building will include sustainable energy sources and more efficient construction methods to meet net zero carbon targets.
Ground Conditions
Made ground typical of colliery waste was across the entire site, from depths of between 0.2m and 2.5m (0.4m to 2.2m thickness). The material generally comprised dark grey and brown sandy clayey gravel/gravelly clayey sand. The gravel comprised fine to coarse angular to subrounded mudstone, siltstone, sandstone and coal, with localised brick and clinker. Additional upfilling was required to the west of the site to create a continuous working platform for the Vibro Rig.
Solution
The presence of uncontrolled made ground and loose sands made impossible any construction without unacceptable residual and differential settlement. The Structural Engineer opted for a raft foundation to further minimise settlements by spreading the load over a large area. Due to dense layers of made ground a Pre-auger rig was used to assist with the installation of the Vibro Stone Columns (VSCs). A total of c.750 VSCs were installed to depths between 1.5m and 4.1m in a little over 2 weeks.
