Securing of tunnel excavation ahead of progressing working-face using the grouting system GEOPUR – Kolektor centrum Ostrava site (underground utility tunnel construction)


Design for the tunnel construction required a min. 2 MPa bearing strength of overlaying rocks after grouting.
The proposed technology was based on grouting of overlaying rocks ahead of the working-face by polyurethane grouting system GEOPURâ into the distance of 3,5 m. In the given geological conditions (fluvial gravels of the River Ostravice) the technology proved to be a safe and economic solution. The use of polyurethane grouting resin systems GEOPURâ (types 082/1000, 082/600,082/350 and 082/90) enabled to perform the whole cycle of grouting works in 4 hours. 3,5m long grouting bars of small profile made possible their quick installation.
Proposed technology does not require any equipment of great size. Borings for grouting bar installation were drilled using a light hand drilling equipment; grouting works were performed using transportable pumps. Borings were drilled upwards in 8° angle. The technology enabled after the grouting to perform an excavation of 2,2m.
9-12 grouting bars were proposed depending on the local geological conditions for the given tunnel profile. GEOPURâ grouting resin of 082/90 type was used on the sides and 082/600 or 082/350LV in the upper parts of the profile.
Minimal compressive strength of the formed geo-composite reached in the upper part of the profile 4-6 MPa and 2-4 MPa on the sides. The strength of the rock was reached in 20 min after application.

Grouted gravel in the overlaying layers and working face of the tunnel