MECHPLANT'S HEAVY duty 125t load capacity MP125 hydraulic strut was the main force in supporting the excavation of a large basement for a new hotel, nightclub and shopping development in the centre of Manchester.
The 13,000m2 Circus scheme is being built on an island site at the intersection of Oxford Street and Portland Street.
Retained listed facades and the surrounding roads had to be safeguarded throughout excavation of the 7m deep basement.
Mechplant, working with design and build contractor Shepherd, consultant Ove Arup & Partners and Amec Developments, designed a system to support the concrete capping beam to the basement wall, minimising disruption to construction of stairwells, lift-shafts, columns, drainage and services.
The system was also designed to be dismantled and removed from a confined space, once the ground-floor slab had been cast on top of the capping beam.
The support system, comprising 26 MP125 hydraulic struts installed around the 69m long and 41m wide excavation at 10m centres, had to sustain a maximum load of 138kN/m.Most of the struts were raked down from the capping beam to concrete thrust blocks cast at basement level.
Mechplant designed these to provide additional shear restraint needed at the capping beam because of the high shear forces generated in the struts. Two of the struts were installed horizontally across the capping beam to act as corner struts.