Szczegóły publikacji
Opis bibliograficzny
Application of the NATM method in the road tunneling works in difficult geological conditions – the Carpathian flysch / Zbigniew NIEDBALSKI, Piotr MAŁKOWSKI, Tadeusz MAJCHERCZYK // Tunnelling and Underground Space Technology ; ISSN 0886-7798. — 2018 — vol. 74, s. 41–59. — Bibliogr. s. 59, Abstr. — Publikacja dostępna online od: 2018-01-11
Autorzy (3)
Słowa kluczowe
Dane bibliometryczne
| ID BaDAP | 111594 |
|---|---|
| Data dodania do BaDAP | 2018-02-02 |
| Tekst źródłowy | URL |
| DOI | 10.1016/j.tust.2018.01.003 |
| Rok publikacji | 2018 |
| Typ publikacji | artykuł w czasopiśmie |
| Otwarty dostęp |  |
| Czasopismo/seria | Tunnelling and Underground Space Technology |
Abstract
The paper presents the characteristics of geological, geotechnical and construction conditions in the Laliki tunnel in Carpathian flysch. Until now, it is the only tunnel constructed there; yet, another one is underway, and several more are in the design stage in Poland and Slovakia. Therefore, the experience gained during construction of this tunnel using NATM method are extremely important from the point of view of further tunneling works. The analysis has shown that the flysch formation met in Laliki is different from e.g. in Greece which is better known from tunneling. The changes in geological and engineering conditions along the tunnel, mainly in dip of rock layers, approximately between 70 and 85°, and a varying lithology, led to diversification of the quality of the rock mass and its different evaluation on the design and tunnel execution stages. Changes observed in the rock mass quality have forced the contractor to apply a primary support with a higher load-bearing capacity, i.e. using micropile umbrella system, which was not planned before. The determined RMR, GSI and KF (Polish classification of the Carpathian flysch) rock mass quality indices shown significant discrepancies that proves high subjectivity of the methods in the condition of flysch formation. Simultaneously, the analysis has shown that KF classification can be applied in flysch rock mass successfully, together with RMR and GSI classifications. The paper also analyzes selected monitoring elements covering convergence measurements of the primary support and the surface subsidence. So called Squeezing Index SI, designed by Singh (based on Barton solution), was used to set the critical deformations. Also warning levels of tunnel stability loss proposed by Sakurai were implemented to predict the potential flysch rock mass deformations. The analysis shows the good correspondence between the rock mass propensity to deform and the applied support, however the support was not adjusted adequately to the ground conditions at some sections. It become apparent that in flysch the rock mass evaluation is not yet researched well and resolved. As a consequence of the wrong evaluation is a pronounced displacement contour and a need of additional support. The results of surface subsidence indicate that the high dip of the strata and the shallow tunnel depth (here – up to 35 m) are the major factors of the asymmetrical shape of the trough and the long-term deformations (6 years), even in the sections where the rock mass quality was evaluated high. The claystone content and steep dip of the strata are critical in this aspect, because they both lead to the shear displacements. The observations and experience gained during Laliki tunnel drivage are the basis for the designs of new tunnels in flysch rock mass in this part of Europe.