ABSTRACT
In the area of the layers of the ophiolitic sequence, the tunnel has a height of overburden between approx. 300 and 530 m. The layers to be expected are schistous serpentinite (se.s), serpentinite (se) and to a minor extent schists, cherts and basic lavas. The schistous serpentinite has a distinct schistosity with limited shear strength, which forms the dominant discontinuity, resulting in anisotropic strength and deformability of the se.s. Material properties of the se.s vary. Sections with lower and higher strength are observed. The se reveals basically the same characteristics as the se.s, however, it has no distinct schistosity, and the properties are slightly more favorable. In both layers, shear zones with properties of a cohesive soil have to be expected on 15 to 20% of the length. As a rule, the thickness of the shear zones varies between 1 to 3 m, with a maximum thickness of 15 to 20 m. In the area of
ABSTRACT: In course of the new highspeed railway line from Athens to Thessaloniki, the approx. 9 km long Kallidromo tunnel is to be constructed with two single-track tubes. After completion of approx. 2 1.5 km on either side, the works had to be interrupted in 2002. Difficult heading and failures of the support had to be dealt with in squeezing ground. Design for the remaining tunnel sections was re-done. For the tunnel sections in squeezing ground, a yielding support with a slotted shotcrete membrane and a special type of yielding anchors is foreseen in the new design.
