CERN HL-LHC POINT 1, hiDCon

Flexible, temporary lining to reduce high bending and compressive forces in the shotcrete shell during the construction of the caverns US/UW17, an innovative solution with hiDCon elements

Difficult geology, swelling rock, anisotropic stress distribution

The Large Hadron Collider (LHC) project involves tunnel constructions with complex geometries. One example is HL-LHC Point 1, where a shaft leads into a service cavern (US/UW17), which in turn is connected to two tunnels.

The structure was constructed in a difficult geology with swellable marls and anisotropic stress distribution. During construction, high bending and compressive forces had to be expected in the shotcrete of the temporary cavern lining.

Innovative hiDCon variant with major advantages

To control and limit the expected high bending and compressive forces, a shotcrete lining with compressible hiDCon elements was proposed (see download below). With the hiDCon compression element variant the following advantages could be realised:

the stresses and bending moments in the shotcrete slab could be greatly reduced as controlled convergences were possible
the construction sequence could be significantly optimised (shortened)
the securing measures (anchors) could be greatly reduced
The construction costs could also be considerably reduced