Sonic logging at Crossrail.

Testconsult's foundation testing department are currently working on their fourth Crossrail site at Paddington Station in Central London. Testconsult are sub-contracted by Cementation Skanska to carry out sonic logging on a range of deep piled foundations and diaphragm walls up to 65 metre depth across the whole project.

Testconsult's involvement started in 2011 at Pudding Lane, next to the Olympic Park. Moving onto Limmo Peninsula (Docklands) at one of five tunnel boring machine entrances, it has now progressed through to the station construction phase of Europe's largest construction project.

Testconsult foundation testing department is using the latest SCXT sonic logging equipment, produced by Testconsult Equipment and powered by ultra fast rugged portable computers, which now enable technicians to log a four tube pile profile in around 15 minutes. The advances equate to more testing during a shift and a faster, more efficient testing service for clients.

Sonic logging is the preferred method for assessing diaphragm wall units, as testing can be carried out on buried units and multiple profiles enable any anomalies that exist to be pinpointed for suitable remedial work if required. Unlike integrity testing, there is no depth limitation - only the depth of tubes cast into the unit and the length of the transducer cables. Results are not influenced by soil damping, so analysis of the foundation base is also possible.