Sector: Rail
Scope: Thermal integrity profiling: 74 x 60m bearing piles of 1.2-2.4m diameter and 116 diaphragm wall panels (including corner panels and T-shaped panels)
CemOptics – Northern Line Extension
CemOptics – Northern Line Extension
Construction of the new Battersea Junction Station, part of the Northern Line Extension project, involved two large excavations for the station and track crossover tunnels. These were formed using diaphragm walls with central bearing piles.
The structures encountered challenging ground conditions for both digging and concreting. To verify that the finished concrete was of the required quality, CemOptics was used to carry out thermal integrity profiling (TIP) on all the piles and 50% of the diaphragm wall panels. The bearing piles ranged from 1.5m to 2.4m in diameter the diaphragm wall panels included both corner and T shaped panels.
Over 50km of fibre optic cable were installed across the 190 elements tested. Multiple lengths of fibre were attached to the embedded reinforcement using cable ties. The position of the cables was based on the geometry of the element being measured.
The first panels tested also included cross hole sonic logging (CSL) tubes so that a comparison could be made between CemOptics and traditional techniques. CemOptics clearly demonstrated its advantages, showing it could also identify anomalies within the cover zone and changes in ground conditions.
Since proving itself on this prestigious geotechnical project CemOptics has been included in the Institution of Civil Engineer’s specification for piling and embedded retaining walls and has gained recognition as a valuable addition to the industry.
