interface element was used. Laid on the shield extrados, the role of this interface is to block the radial ground convergence and also to allow the tangential convergence by arch effect. Figure 9 shows the interface element after being activated. The volume loss because of the shield conicity is partially compensated by the possible migration of the grout upward the shield. This migration is simulated by a correction of the shield conicity, set so as to reproduce a vertical displacement recorded on the construction site (back analysis on surface and/or tunnel crown
Magdalena Habrat, Paulina Krakowska, Edyta Puskarczyk, Mariusz Jędrychowski and Paweł Madejski
 PANAHI H., KOBCHENKO M., RENARD F., MAZZINI A., SCHEIBERT J., DYSTHE D., JAMTVEIT B., MALTHE-SORENSSEN A., MEAKIN P., A 4D synchrotron X-ray toography study of the formation of hydrocarbon-migration pathways in heated organic- rich shale, SPE Journal, SPE 162939, 2013, 366-377.
 POPRAWA P., KIERSNOWSKI H., Potential for shale gas and tight gas exploration in Poland, Biuletyn PIG, 2008, 429, 145-152.
 POPRAWA P., Shale gas potential of the Lower Palaeozoic complex in the Baltic and Lublin-Podlasie basins (Poland
Soumia Bellil, Khelifa Abbeche and Ouassila Bahloul
the soil studied, which has a loose structure with many voids, facilitating the migration of fine particles from one level to another [ 5 ].
Reciprocally, compacting at 70 strokes makes the soil relatively dense and the destruction of intergranular bonds, and the movement of the fine particles becomes slow [ 11 ].
3.2 Influence of water content on the collapse potential C p
Table 5 also shows that the collapse potential C p decreases when the water content increases. These results are consistent with those obtained by Abbeche et al. [ 1 , 2 ] and
the results of measurements carried out on the motorway soil-steel bridge in Ostróda [ 8 ] (Poland). A wildlife migration route and a local road pass under the bridge. Since the bridge carries four roadways, each with two traffic lanes separated by a median strip, its width amounts to B g = 61.82 m and B d = 95.70 m at respectively the embankment crest and toe. This bridge structure holds a world record for shell span [ 8 ] (the previous record was held by the shell with L = 24 m built in Canada).
The shells of soil-steel structures are made of corrugated
The displacement-computing algorithm presented in this paper is based on the results of measurements of a bridge in Ostróda (Poland). A wildlife migration route and a local road pass under the bridge. There are four two-lane carriageways, separated by median strips, on the bridge. Hence, the width of the bridge is large, amounting to B g = 61.82 m at the crest and to B d = 95.70 m at the embankment toe. This bridge structure holds the world record for shell span length [ 1 ] (the previous record belonged to a 24-m-long shell built in