Pile Cap and Foundation Beam Detection

5th September, 2018

Our client had purchased a former industrial / business unit with the aim of converting it to a residential property. The client planned to strip the building down to its superstructure and add an additional two storeys. In order to facilitate the design, they required accurate mapping of pile caps and structural ground beams. This information was required to ensure that the current building foundations were sufficient to support the new renovation design.

The building was still in use at the time of survey. The ground floor consisted of two distinct sections. The eastern half was being used as a storage warehouse that had an exposed concrete floor. Our survey team made a monumental effort to clear floor space of boxes and crates to ensure maximum data collection and survey coverage.

The western half of the building was used as an office space. This half had a raised tile floor that prevented data collection. LandScope selected a number of key structural columns and removed the floor tiles that surrounded them. These areas were targeted as floor beams and pipe caps were expected to be present. It was assumed that the information from the eastern half, along with the targeted data from the western half would allow for sufficient interpolation of the pile cap and structural beam layout for the entire business unit.

LandScope deployed two GPR systems for data collection. The first consisted of an UTSI GroundVue3 8 channel 1GHz array. This system is designed for rapid data collection over a large surface area. The second system consisted of a SIR3000 GPR unit with a single 900MHz antenna. This system has a small antenna footprint and was used to collect data in areas of limited space.

The 900MHz and 1GHz antenna frequency range were selected as they provide a sufficient resolution to accurately map reinforcement bars within the floor slab whilst providing enough depth penetration to locate potential pile caps and structural beams below the concrete floor slab.

Once collected, the GPR data was transferred to LandScope’s head office and post processed for detailed  analysis and feature extraction.

GPR analysis showed structural beams to be constructed of concrete with a greater density of reinforcing spacing than seen elsewhere within the floor.

The extent of, and depth to, top of pile caps was successfully determined around multiple structural columns.

Quorum Consulting – Riverview House