Soletanche Polska uses compensation grouting for first time

Compensation grouting is not a commonly used technology in Poland as tunnels usually pass under roads rather than buildings but on the new Lódz line the technique was employed to ensure the TBM’s safe passage under historic residential areas.

The construction of the new underground railway network, which will connect the two stations Lódz Kaliska and Lódz Fabryczna, is particularly complex as the alignment travels across the city, including under residential areas.

Soletanche Polska needed to stabilise the ground and reduce settlement of houses directly above the tunnel under construction so, for the first time, the company used compensation grouting.

After preparation, including drilling boreholes, injection rods installation, and testing pre-injection phase, the Soletanche Polska team proceeded with the final phase of active grouting, which was carried out while the TBM was operating. If subsidence occurred, grout was injected to stabilise the soil.

Computerised control allowed real-time observation of parameters, pressure checks and preparation of daily reports.