Groundforce has introduced a new wireless remote condition monitoring system that simplifies real-time measurement of static loads and monitors potential movements in sensitive structural support applications.
The new wireless system, known as FlatMesh™ from Senceive, uses wireless nodes with the Groundforce load pins, which pass their signal from one to another, meaning that only one of the nodes needs to have clear contact with the 3G gateway module, in order for all readings to be taken. This means not all the load pins need to have direct line of sight with the 3G gateway module, as was the case previous monitoring systems.
One of the first projects to employ the Senceive system was a complex scheme forming part of a major redevelopment of the Royal College of Music (RCM) in South Kensington, including the construction of a new extension in the College’s central courtyard.
The location could hardly be more inaccessible or more sensitive to disturbance. The courtyard is hemmed in on all four sides by existing buildings: the RCM encloses three sides of the site; on the other side are buildings occupied by the Imperial College.
“We are building a 7m-deep basement to within one and a half metres of the existing buildings,” explains Gilbert-Ash project director Ciaran Begley.
Gilbert-Ash approached Groundforce for design help at the early tender stage and awarded it the £120,000 structural support contract having won the £22m main contract.
Groundforce supplied its Mega Brace hydraulic waling beam to support the concrete secant-piled retaining wall, bracing the excavation with M50, MP125, MP150 and MP250 modular hydraulic props.
Due to the complete absence of ground-level access, all the equipment had to be craned in over the RCM building, which was protected against possible damage with a crash deck supported by a scaffold structure.
A reinforced concrete capping beam was cast on top of the pile caps before excavation commenced; all the arisings from the excavation were removed on a special conveyor system that ran through the building to the street where it was loaded into trucks and carried away.
As the excavation progressed, the Groundforce equipment was craned in and installed. Two levels of support were required; the upper level was braced against the capping beam; the lower level against the Mega Brace waling beam.
Vertical support for the props was provided by conventional gallows brackets on the upper level, but the lower level gallows brackets were found to clash with the intermediate slab:” We therefore utilised the use of eye nuts to replace gallows brackets,” explains Groundforce sales engineer Nadir Salim. “These were drilled into the capping beam and restraint chains were slung down and attached onto the Mega Brace”.
It was essential that the loading on the support structure were continuously monitored throughout the excavation process, Senceive’s FlatMesh™ system monitored the loads impinging on the hydraulic struts, alerting the construction team to any changes that could mean unwanted movement in the ground or surrounding structures.
As it was, the design and execution of the basement construction went without a hitch.
“Groundforce were really, really fantastic. They helped us from the pre-qualification stage right through to completion of the basement. The piling and propping were top priority from day one,” says Ciaran Begley. “We were also grateful to Groundforce for their meticulous planning,” adds Ciaran. “Every piece of kit arrived exactly when they said it would which made life so much easier as we only have a very small lay-down area and any delay or unexpected delivery could have caused problems”