Main difficulties and lessons learnt during the TBM excavation in shales in the North portal of Pajares tunnels

Aguado, María Belarmina Díaz; Muro, J. García de; Rodríguez, Roberto

doi:10.1201/b16955-96

Cited by 2 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The geology of the Pajares variant tunnels was well-described by Alonso and Rubio [41], who analyzed the area marked in Figure 2. This particular stretch of the tunnel, called the San Emiliano formation, presented singular stability problems [42,43]. The Bolaños tunnel has a 10 m diameter and is a twin tunnel, though we analyzed only one of them in this study.…”

Section: Case Studiesmentioning

confidence: 99%

“…The risks of entrapment and gas emissions were other potential setbacks that did not occur, despite that they were prone to occur in the actual geological conditions found, and therefore, they must be counted in the assessment of the project [42,43]. The potential entrapment, with an average of 30 days, would have a total fixed cost of EUR 900,000.…”

Section: Pajares Variant Lot 3 Tunnelmentioning

confidence: 99%

See 1 more Smart Citation

Directional Core Drilling as an Approach to Reduce Uncertainty in Tunneling Construction

Rodríguez,

Fernández,

Bascompta

et al. 2023

Applied Sciences

View full text Add to dashboard Cite

The definition of a rock mass’s characteristics is crucial in underground construction to avoid delays and cost overruns. This study proposes a system to quantify the economic uncertainty related to a lack of knowledge of a rock mass in the tunnel construction stage, either for tunnel boring machines or for drill and blast excavation techniques. Using a back-analysis of three actual tunnels completed in Spain (Burata, Lot 3 of the Pajares variant, and Bolaños), the study assessed the directional core drilling technique (DCD) for this purpose, comparing it with conventional boreholes. In this regard, the DCD approach reduced the uncertainty by between EUR 6.7 and EUR 12.7 for every EUR 1, while the total cost of the drilling campaign remained within a widely accepted proportion of the construction budget. Overall, the uncertainty was reduced by approximately EUR 6000 per meter of the tunnel.

show abstract

Section: Case Studiesmentioning

confidence: 99%

Section: Pajares Variant Lot 3 Tunnelmentioning

confidence: 99%

Directional Core Drilling as an Approach to Reduce Uncertainty in Tunneling Construction

Rodríguez,

Fernández,

Bascompta

et al. 2023

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…The connection to the existing segments were carried out with steel connectors (Figure 5b), -Demolition of the central segments and completion of the steel collar (see (Figure 5b), -Excavation of the cross passage with conventional tunnelling according to NATM, From a geological point of view the San Emiliano formation is a complex carboniferous formation, mainly constituted by shales and black slates but also composed of sandstone, limestone and some thin non-exploitable coal seams folded with an estimated value of RMR from 20 to 70 [5]. During the construction sequence, the values of encountered RMR were, in fact, between 35 and 55 [6], which lead to an in-depth revision of the geotechnical parameters [4] employed for TBM lining and cross passages as shown in Table 1.…”

Section: Fig 2 3d Simulation Of Tbm Cross Passages With Structural mentioning

confidence: 99%

“…The general overestimation of the ground parameters in the Pajares Tunnel [4] during tender design produced local entrapment of the TBM [6] and the Client decided to increase TBM lining from the 0.5 m proposed in the tender design to 0.6 m. This increment of the lining depth also affected the cross passages, which needed a structural redesign during the first excavation process [7]. Table 2 collects the first lining changes carried out during the construction stage; moreover, to avoid squeezing effects on cross passage tunnels, the secondary lining…”

Section: Fig 2 3d Simulation Of Tbm Cross Passages With Structural mentioning

confidence: 99%

Cross passages between TBM tunnels: The experience in Spanish high‐speed railway tunnels

Iasiello

Torralbo

Caldentey

2019

Geomechanics and Tunnelling

View full text Add to dashboard Cite

This paper describes, by means of two practical examples, the different approaches employed to design and build cross passages between segmental lined tunnels for high speed railway lines in Spain. The increment of principal stresses at the cross passages leads to the need of an additional support system for the tunnel lining. The chosen solution for this support system depends mainly on the ground conditions, the tunnel overburden and contractor's local experience. The first example is related to the Pajares Tunnels bored in the San Emiliano formation and the second one collects the experiences of the Guadarrama tunnels bored in very hard gneiss and granite rocks. The aim of this paper is to establish some key aspects to be considered when choosing the cross passage design and the corresponding excavation process.

show abstract

Main difficulties and lessons learnt during the TBM excavation in shales in the North portal of Pajares tunnels

Cited by 2 publications

References 0 publications

Directional Core Drilling as an Approach to Reduce Uncertainty in Tunneling Construction

Directional Core Drilling as an Approach to Reduce Uncertainty in Tunneling Construction

Cross passages between TBM tunnels: The experience in Spanish high‐speed railway tunnels

Contact Info

Product

Resources

About