Salzburg concentrated on moving forward Oct 2014

Shani Wallis, TunnelTalk
It is 20 years ago that collapse of NATM excavations on the Heathrow railway link in the UK in October 1994 rocked the tunnelling industry and while NATM was discussed in different aspects at the 63rd annual Salzburg Colloquium and its biennial Tunnel Day in October 2014, looking back at Heathrow was not one of them. The dialogue was on developing the contractual aspects of NATM in its classic form and refining its methods and techniques to both open-face and TBM driven headings. TunnelTalk attended the conference and reports on the proceedings of one of the most anticipated fixtures in the annual conference calendar.

October 2014 is the inauspicious anniversary of one of the most unforgivable occurrences in the tunnelling industry but reviewing cause and effect of the notorious Heathrow collapse in October 1994 was not on the agenda of the Salzburg Geocolloquium and its TunnelDay series when delegates from across Austria and the predominantly German speaking countries of Europe convened for the annual event. That was part of the last Tunnel Day programme in 2012 when the experiences of adopting NATM around the world were brought together for discussion. TunnelTalk was there and reported the proceedings (see References below).

Full face or sequential face excavation – that is the question
Full face or sequential face excavation – that is the question

This year, the conference programme, delivered to an always large colloquium delegation of 1,000 or more, included:

  • discussions about the challenges of managing large construction sites,
  • a construction related focus on risk management,
  • the pros and cons adopting full-face versus sequential face excavation for open-face NATM works,
  • site investigation and tests for TBM-specific ground characterization,
  • the protential of excavated material as a mineral resource rather than as a waste; and
  • the orientation of tunnel design for efficient maintenance and sustainability.

As always, there was active discussion and participation from the floor- the lecture auditorium assured to be full with only one tack of lectures rather than simultaneous sessions- and for non-German speaking attendees, the excellent simultaneous translation to English keeps everyone engaged. There is also the accompanying set of proceedings, which is something of a rarity at conferences these days. The papers are presented in German and English and published as Volume 7 of the monthly magazine Geomechanik und Tunnelbau - Geomechanics and Tunnelling published by Ernst & Sohn for the Austrian Society of Geomechanics.

In addition to the technical sessions, scheduled over three days, there was a packed exhibition area of industry exhibitors, and the anticipated set of social events included the Tunnel Day reception at the Castle overlooking Salzburg and the Chamber Music concert at the Residency Building, followed by the evening meal and revelry at the keller on the Geocolloquium Thursday evening.

Socialising management to avoid disputes in contracting
Socialising management to avoid disputes in contracting

Contracting practices

In his keynote presentation on Tunnel Day, Prof Water Purrer recalled a heated discussion at the 2010 Tunnel Day about where is NATM going, which identified that much of the discourse on the topic centred on contractual disputes. "Claim management had become something of a cold war," said Purrer, "which required a disarmament process," he said, "but who would start to disarm first?"

“Finding someone to blame for disputes is a technocratic approach to the issue," said Purrer. "A low price award, some say, is to blame but who is to blame for that – the contractor who offered the low price or the client who accepted it?” Purrer then quoted Einstein, who said “You can never find a solution by using the same thinking that caused the problem in the first place”, to suggest a social solution to avoiding and settling disputes. “Find cooperation and use this as a catalyst for mutual trust,” was his recommendation.

Socialising the process, he suggested, would require, among other things, reliability in the tendering process with procedures for bid evaluations established before tenders are submitted. He also suggested that value engineering should be given time, at least six months, to be fully appreciated and integrated into project designs.

As leader of a working group assigned to examine the state of contracting practices, Purrer said that a model for the contract negotiating process, from a more socialised point of view would be published before then end of the year for distribution and discussion.

Winner receive the prize from Prof Galler
Winner receive the prize from Prof Galler (right)

Prizes for innovation

An important part of the conference is presentation of the Tunnel Day prize for innovation, and this year, from eight entries, four prizes were awarded.

First prize was for a novel method for generating the conditioning agents for use with EPB TBMs. Submitted by Norbert Hörlein of PORR and Eugen Kleen of MC-Bauchemie, the system reduces the amount of chemicals used to produce conditioning foams of constant quality.

Second prize was awarded to Clemens Niemayer, Franz Deisl and Klaus Mitteregger of TIWAG-Tiroler Wasserkraft AG for a new two stage approach for engaging engineering companies. The concept comprises a base phase for evaluating proposal price, key personnel and procedures, and a second phase that explores value engineering ideas and innovations. The successful engineering company then shares the cost saving benefits of progressive ideas if these are managed well through the construction period. The objective is to provide a sensible and fair method for allocation of contracts to engineering service providers.

A joint third prize, was awarded. First to a partial face excavation reamer for accurate profiling of the inverts and crowns of open face excavations submitted by Wolfgang Poschacher of G Hinteregger & Sons Construction Company and Peter Huemer of Huemer GmbH Betonbohr- and cutting, and secondly to a mechanical method of eliminating hard physical work to improve occupational health and safety of the miners, submitted Jürgen Voringer of G. Hinteregger & Sons Construction Company, Kurt Joham of PORR and Albrecht Rombold of Rombold & Gfrohrer GmbH.

Entrants for the Tunnel Day Innovation Prize
Entrants for the Tunnel Day Innovation Prize

The four other entries were:

  • A new role of the testing institute as a consultant to a project from the tendering phase to capture innovative solutions and provide consistent quality assurance through the construction period;
  • A new hanger system for false ceiling panels;
  • A system of using the operation of the TBM itself as the source signal for seismic and geophysical investigations ahead of the face; and
  • A new system to repair water-bearing cracks in the final lining where previous remedial measure in a 25 year old tunnel with no waterproofing membrane had failed.

As part of the sessions, a presentation by Ing Köhler of PORR as leader of a JV for management of the 65.3km Doha Metro Green Line contract in Qatar addressed the topic of managing large construction sites. The contract includes 37km of twin running TBM-bored tunnels using six Herrenknecht TBMs, and with several of the 31 stations underground.

Prof Robert Galler of Leoben University introduced the R&D Dragon Project, which is supported by the European Commission and intended to develop new technologies for processing excavated material as a valuable mineral resource rather than a waste by-product. The presentation opened a full session of five additional presentations on the topic.

Prof Barla of Turino Univeristy presented the ADECO system of full face excavation
Prof Barla of Turino Univeristy presented the ADECO system of full face excavation

The session devoted to full face versus sequential face excavation included a paper by Schubert and Voringer that addressed the criteria for the selection of each and from the geotechnical and logistical points of view.

As part of the session devoted to TBM-specific site and geological investigation, Prof Markus Thewes of Bochum University described a testing scheme to assess the clogging tendency of material on TBM projects.

Life cycle costs, as well as the refurbishment of highway tunnels and the design of effective drainage systems for operating tunnels, were discussed in a session dedicated to tunnel design for optimum maintenance and sustainability - a topic that rarely receives the attention it deserves and requires. Papers in the session addressed the topic for long rail tunnels,in particular for the Semmering Baseline, Benner Baseline and Koralm tunnels.

In closing the conference on Friday afternoon, Prof Wulf Schubert, President of the Austrian Society of Geomechanics welcomed the full delegation back to Salzburg next year in October when the Geomechanics Colloquium will also host the ISRM regional symposium EUROCK 2015.

After another successful and enjoyable conference in Salzburg, TunnelTalk sends a warm Glückauf to the organisers and everyone we met and best wishes for meeting again next year.

Copies of the proceedings, and proceedings for previous Salzburg Colloquia, available from Ernst & Sohn.

Further details for EUROCK 2015

Website for the Austrian Society of Geomechanics


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