TBM experiences from the Koralm railway tunnel (Austria) and re-use of TBM muck. Gerhard HARER

Transcription

1 TBM experiences from the Koralm railway tunnel (Austria) and re-use of TBM muck Gerhard HARER

2 2 Project overview Koralm railway Part of the Baltic-Adriatic Core Network Corridor, which is one of the most important transeuropean traffic axes. Client Ref.: baltic-adriatic.eu

3 3 Project overview Koralm tunnel 32,9 km 2 tubes, 2 ventilation shafts, 1 emergency stop 1/3 NATM, 2/3 TBM Ref.: ÖBB, 2015

4 4 Project overview Koralm tunnel - Geological framework E KAT1 Tertiary sediments KAT2 Crystalline basement KAT3 W Tertiary sediments 32,9 km Exploratory tunnels Ref.: Harer/ÖBB, 2014

5 5 Excursus: Selection of the appropriate excavation method The selection of the appropriate excavation method is one of the most crucial decisions for a tunnel project. It is influenced from a plenty of parameter, such as: Geological conditions Excavation lengths and cross section Construction program Logistic demands and accessibility Environmental aspects Dumping demands and the re-use of mucking material...

6 6 2 TBM lots KAT2 & KAT3 Ref. Infothek.bmvit.gv.at KAT2: TBM-DS km KAT3: TBM-S (EPB) 10.5 km

7 7 Lining concept Single shell lining In general drained Pressure-tight for sediment section KAT3 Option for inner lining Ref.:Harer/ÖBB, 2014

8 8 High-performance hard-rock TBM KAT2 Technical data*: DN = 9.93 m Cutter dia Spacing 80 mm Driving power 4,900 kw Contact force 20,000kN Torque nom. 7,800 knm Torque max. 30,000 knm *) according to technical offer JV KAT2 Ref.: ÖBB, 2013

9 9 TBM performance KAT2 Start of TBM excavation 2012/2013 Already excavated 12.4 km (S) km (N) Best daily performance 45.7 m Best weekly performance 210 m Recent weekly average performance 100 m Excavation rate Status: 03/ /2013 Development of excavation rates (South tube, schematic) 2014 fault zone 2015 Construction time

10 10 TBM performance KAT2 Geological conditions are not significantly different compared to prognosis The technical performance of the JV is outstanding However, a time lag between planned and actual advance occurred So what is the reason of the loss of time?

11 11 TBM performance KAT2 Singularities: A collapse within a predicted major fault zone caused severe time loss and required additional measures Crumbling/friable rockmass and insufficient annular bedding required additional injection measures (which negatively affected logistics) to avoid additional load and deformation of the tunnel lining Ref.: Harer/ÖBB, 2014

12 12 TBM performance KAT2 Decrease in penetration: Penetration decreases locally from 4-6 mm/rev. down to 1 2 mm/rev. Locally increased rock stress is the most probable reason for local decrease of penetration (Büchi, 2014) However, This theory is controversially discussed How to predict realistically abnormal stress conditions?

13 13 TBM performance KAT2 Cutter disk damages: Outbreaks in heading face cause extraordinary high damage of disc cutters The original cutter wear decreases from roughly m3 cutting volume/disc down to 100m3 cutting volume/disc

14 14 TBM performance KAT2 Conveyor belt damages: Locally friable and crumbling conditions cause coarse, swordshaped blocks (passing the primary crusher and cutting the conveyor belt) Increase of primary crushing negatively influences the re-use of mucking material normal mucking material sword-shaped mucking material

15 15 TBM performance KAT2

16 16 TBM performance KAT2 TBM defects: TBM possesses unexpected high requirement of maintenance and repair Main bearing and main bearing seal Cutter head welding Motors Fire

17 17 TBM performance KAT3 South tube excavated by means of NATM TBM excavation started in N-tube in late 2015 Already excavated 2.2 km Ref.: metz-partner.at, 2015

18 18 Re-use of mucking material (KAT2)

19 19 Mucking material flow (KAT2) Total excavation 8,6 Mio. to Concrete 1,5 Mio. to Open sections 2,9 Mio. to The re-use of 60 % of the excavated material is part of the project! Dumping 3,0 Mio. to External recycling 1,2 Mio. to (removal by rail)

20 20 Typical petrology for aggregate production Ref. Posch & Tauer, 2016

21 21 Typical petrology for aggregate production Ref. Posch & Tauer, 2016

22 22 Requirement of extensive site logistics (KAT2) Ref. Posch & Tauer, 2016

23 23 Principal facilities (KAT2) Primary crusher on the TBM Conveyor belts (horiz. & vert.) Pre-screening Secondary screening (option.) Gravel and sand plant Aggregates deposits Rail loading facilities Feeder line Open sections and dumping grounds Ref. Posch & Tauer, 2016

24 24 Aggregate production (KAT2) Up to now (03/2016) 550,000 t successfully produced Ref. Posch & Tauer, 2016

25 25 Aggregate production (KAT2) Processing rate: Highly volatile Rate (products : input) at present appears to be slightly lower than predicted However, rate tends to increase (since improvement measures have been successfully established) Ref. Posch & Tauer, 2016

26 26 Re-use of TBM muck concluding remarks: Material processing must be properly designed in advance However, only a few reliable/coherent data from former projects are available Petrological & geochemical conditions as well as the degree of fracturing are highly influencing the output rate Furthermore cutter head design and TBM operation may influence the grain size distribution of muck It s a specialist s job Best available technology, material and interface management, triage at the face and partnership are required

27 27 Re-use of TBM muck concluding remarks: No shortages in supply occurred Excellent products were achievable (C35/45 up to C50/60) However, the average output rate in the past appears to be slightly lower than predicted The project was honored with an award from the Federal Ministry of Agriculture, Forestry, Environment and Water Ref.: oewav.at

28 28 Concluding remarks TBM drives: Investigation and design, which considers specific ground parameter and behavior is essential for TBM-, excavationand support design Competent staff on site, good workmanship and partnership are absolutely necessary (both contractor and consumer) To consider only net penetration rates or daily performance is misleading The occurrence of singularities has to be respected Flexibility is very limited in comparison to NATM/drill&blast, in particular in case of special situations Logistics directly influences the advance rates

29 29 Concluding remarks TBM drives: We are exactly in time and budget (Harer, Oslo 2014) As per the information of ÖBB this is still valid, since a proper overall risk assessment has been made and risk mitigation measures were planned in advance. However, the system limits might be reached soon. Different perceptions of contractors and owner regarding deviations and spheres will cause contractual claim negotiations.

30 30 Concluding remarks TBM drives: The selection of the appropriate excavation method (and a suitable TBM system) is one of the most crucial decisions Since the geological risk belongs to the owner it is also his responsibility to define appropriate minimum criteria It is also in the responsibility of the TBM suppliers not to arouse false hopes It seems that properly evaluated ground parameter do not fully flow in the TBM design Further research and improvement is requested Communication across the interfaces customer consultant contractor supplier has to be improved

31 31 Concluding remarks TBM drives: For the lot KAT2 Continuous investigation in advance of heading is performed (TSWD, if required probe drilling) to reduce uncertainties The complex interplay between logistics and TBM excavation was underestimated A state-of-the-art excavation with NATM/drill&blast would have caused considerable additional works and expenses (addl. ventilation shafts, widening of diameter,.) The average daily advance with TBM (in average 13 m/calendar day) is better compared to NATM/drill&blast and comparable or larger than in comparable projects

32 32 Concluding remarks TBM drives: The advantages of TBMs in the author s opinion arise esp. in: Uniform tunnel shapes (constant diameter, no niches etc.) Long tunnels (taking into account construction time, logistics, ventilation, environment,.. 10 km?) Smaller diameters Homogenous geological/geotechnical conditions Soft ground tunnels with little overburden

33 Thank you very much for your attention!