Frejus Exploratory tunnel site visit

Site visit to Frejus Exploratory tunnel:

40 ton crane at the main portal of the jobsite.

Segment Factory:

Segment mould with anchored gaskets installed and oiled.

Concrete casting of the key segment.

Connector socket and spacer for the reinforcement.

Forklifts for the segments handling.

Anchored gasket installation on the mould.

Longitudinal joint of the segment with guiding rod.

Invert precast segments.

Segments stockage area.

Underground TBM assembly cavern:

TBM's shield and cutterhead during assembly. 

Lifting device for the assembly of the TBM's shield components.

Overhead crane for the assembly of the backup.

Main bearing of the TBM.

Launching pit of the TBM.

Week 19: Some remarkable case histories

During this week we had the opportunity to gather some of the most interesting case studies of the carrier of Brian Fulcher (Ex Kenny Construction Company, USA). He introduced cases such as metro line extension in 72nd street NY and Rio Piedras in Puerto Rico, explaining the keys of the successes and defeats he faced during this challenging projects.

Brian Fulcher and the students after his lecture.

Going on this week, Berenice Moreau (CETU, France) held an outstanding lecture on segmental lining design for fire resistance. Starting from the analysis of the catastrophic fire events that took place in the late nineties all around europe, she went through the evolution of the laws and norms concerning the lining design to introduce the theories proposed and in use nowadays in order to bring safety inside the tunnel not only in terms of stability but mainly for the people passing through. 

Berenice Moreau and the students after her lecture.

Daniele Martinelli (Politecnico di Torino) presented a great lecture on abrasivity tests to be carried out in the laboratory for the assessment of the wear phenomenon of the tools during the excavation process. Even if there are some standard tests very well known and correlated to the cutting tools life, there is also a great research on going to find tests that are more and more representative of the true conditions to be found on site.

Some representers of Pini swiss engineers came to present the project of Ceneri Base Tunnel they worked on as designers in the last years. Davide Merlini as the chief manager of the project, presented its main aspects and peculiarities. Stefano Morandi talked about the geological features as the Site Supervisor in Sigerino adit. Mateo Falanesca presented the approach adopted for the design of rock excavation and finally Francesco Rossi explained the case of a portal through filling material below a highway under operation, a masterpiece of engineering.

Pini Engineers and the students after the lecture.

Finally, Giovanni Giacomin (Ghella Mechanised Excavation Manager) presented two great case histories. Starting from Maldonado sewage system in Argentina, a two tube system to cope with the constant floods of Buenos Aires city with a pumping station to the sea. Then he presented a fantastic project developed in Australia for the Brisbane Legacy Way, an outstanding performance in terms of quality security and logistics.

Giovanni Giacomin, his son and the students after his lecture.

Week 18: Visit to TUSC laboratory

To start with this 18th week of the T&TBMs MAS Course, Gustavo Bomben from FAVA company held a great lecture presenting their products, the technology and research behind them. The main focus was Gaskets and Connectors for segmental lining, they are pioneers in the market developing precise and smart solutions to guarantee a watertight and durable lining system.

Gustavo Bomben's lecture on Gaskets and Connectors for segmental lining

Later on, we went to Politecnico di Torino TUSC (Tunnelling and Underground Space Center) Laboratory where Daniele Martinelli and Cristina Oñate Salazar (PhD TUSC researchers) carried on some of the most common tests on soil conditioning to asses the proper dosage. As the tests used for this purpose are varied and come from other industries (concrete mainly), the ability of the operators and experience in the use of the conditioning agents is the key to obtain a proper conditioning of the soils.

Daniele Martinelli, Cristina Oñate Salazar and the students in the TUSC laboratory.

Marco Arato from Atlas Copco presented a complete lecture on mucking systems for mining and tunnelling. He went thoroughly through the main features of their available systems for the handling and transport of the excavated material. LHD (Load Haul Dump) vehicles and train systems are their most developed spoiling techniques.

Marco Arato's lecture on muck transport systems.

Week 17: TBM complementary facilities

Tommaso Grosso from Astaldi presented a set of case histories emphasising mainly on his last project at Warsaw metro. He described thoroughly the organisation of the jobsite in the urban area where space is very limited and the logistics are of main importance to avoid interferences and increase the productivity of the excavation process. Special attention was paid to the TBM assembly, launching, station crossing and arrival of the machine, that require tailor-made engineered solutions as these are critical processes.

Eng. Tommaso Grosso and the students after his great lecture.

Professor Daniele Peila presented the technology and design methodology of Conveyor belts for muck transport in TBM driven tunnels. He based his lecture on a recent real case for a 7 km tunnel below the Alps. Designing every component of the system for the peak production expected is a must in order to avoid advancement limitations. This is a complex system that enhance the mucking out processes for medium to long tunnels reducing interference with the jobs and the risk of accidents due to vehicle impact to workers that is the main source of injuries for all projects.

During this week we had also the presence of Michele Mangione (ARUP) talking about segmental lining design and some very interesting case histories from his worldwide experience. His dynamic approach was the key to merge his knowledge with our interests in topics such as cross passages construction.

Michele Mangione and the students after his lecture.

A fantastic lecture was given by Richard Schulkins (MAPEI) regarding soil conditioning and backfilling grouting. His great experience in job sites all around the world was clear from his practical approach to treat topics that should not be tackled theoretically but from the continuous analysis of the conditions in the machine during the advancement. Each of these topics should never be disregarded as even if they may seem complementary, they play a paramount role on a smooth and efficient excavation process.

Richard Schulkins and the students after his lecture.

Week 16: Hard Rock TBMs

This week was fully dedicated to Hard Rock TBMs and some site organisation concepts concerning the miscellaneous systems to be taken into consideration for a mechanised tunnelling jobsite.

Mr. Brian Khalighi (Robbins, Engineering Vice President), held a fantastic lecture on Hard Rock TBMs coming from one of the most pioneering companies in the field. He went through the evolution of the technology applied to excavate this type of ground from the days of the foundation of the Robbins company until the last case studies in the most challenging conditions. He introduced as well the main features of Open Shield, Single Shield and Double Shield Machines, treating paramount aspects such as:

• performance, 
• cutterhead and cutting tools,
• ground improvement,
• backup systems,
• muck removal and 
• long distance tunnels considerations.

Brian Khalighi and the students after his lecture on Hard rock TBMs

To close with this week Dr. Massimo Concilia (Pizzarotti), held a very interesting two day course on how to choose or adapt already owned TBMs for Hard Rock conditions from his wide experience in the construction field of mechanised tunnelling. Based on some key cases he pointed out the most important factors to be considered while driving TBM tunnels and remarked the importance of a tailor-made precise solution to avoid some of the worst consequences to happen during the project. In addition he discussed about the jobsite planning and organisation in terms of logistics to enhance the productivity and reduce as much as possible the interferences and downtimes.

Excerpt from Massimo Concilia lecture on Hard Rock TBMs design

Week 15: Numerical Modelling and Monitoring of TBMs Advancement

This week in T&TBMs Master was devoted to the study of TBM advancement with lessons held by experts coming one more time from Geodata Engineering S.p.A. First some simplified 2D numerical models were defined to simulate a TBM driven tunnel behaviour and then we analysed as well the real parameters obtained from the machine driving and monitoring system.

Once again, Vincenza Floria (Geodata) gave us a two day practical course on FLAC 8.0 to model the advancement of the machine. The approach adopted for the simulation was the application of a relaxation factor known as the stress reduction method by Panet and Guenot (1982), in order to allow some gradual convergence of the excavated section before the installation of the lining. An interesting task required to perform a parametric analysis to understand and verify the influence of some factors as ground or lining properties and natural state of stress on the model behaviour. From this basic use of the software I could understand that it is a very powerful tool that requires a deep knowledge of the governing background theories.

Excerpt of a parametric analysis exercise done with FLAC 8.0

Finally Giampiero Carrieri (Geodata) held an outstanding lecture on TBM monitoring, not only regarding the machine driving parameters but also of the interaction between the excavation and the already existing structures. He focused on the importance of a well defined monitoring plan to take into consideration as a key tool for the Risk Management Plan, properly defining thresholds and countermeasures to be taken. His approach for the introduction of the topic was based on the presentation of several case histories from his most relevant projects.

Giampiero Carrieri and the students after his lecture on TBM Monitoring

Week 14: Facing Geological Particularities with Closed Shield Machines

This week in T&TBMs MAS Course was dedicated to the analysis of some particular geological situations that require attention when driving a TBM tunnel as well as to the study of EPB and Hidroshield Closed Shield mode machines. 

We had the privilege of receiving a lecture from Prof. Dr. Paul Marinos (NTUA, Greece) entitled Geological Constraints and Geotechnical Issues in Mechanised Tunnelling. He went through several situations that may be encountered when driving a mechanised tunnel from his wide experience as karstic voids, unpredicted hard/weak rock zones, squeezing ground or high pressure water presence. He provided also the main factors that need to be taken into consideration for the right choice of the machine, presenting many case histories to emphasise that each machine must be carefully selected.

Paul Marinos and the Master's students after his lecture.

After getting a clear idea about the choice of the machine, Alessandro Cresto (Herrenknecht) held an outstanding lecture to explain us thoroughly the EPB and HS Closed Shield TBM main features and technological aspects. In a three day intensive course he focused mainly in topics as:

• field of applicability and potentialities of each type of machine 
• main components design and materials
• components wear and maintenance operations
• special reparations
• support pressure
• backfilling grouting
• guidance systems

A strong background was provided by him presenting some very interesting and impressing case studies from his personal experience in one of the leading TBM construction companies, giving us also a general overview of the trends of the market.

Alessandro Cresto and the students after his lecture on EPB and HS.

Week 13: Closed Shields and Face Stability Design

To begin with this week, Prof. Dr. -Ing. Markus Thewes (Ruhr-Universität Bochum) held a fantastic lecture on Slurry Shield TBM technology. From his consistent research background and his wide experience on the application of this type of machines he covered deeply the most important issues to be taken into consideration. The slurry circuit, separation plants, bentonite suspensions, face support and difficult project conditions were the key points.

Markus Thewes and the Master's students after his lecture on Slurry shields.

Moreno Pescara from Geodata Engineering SpA, gave us a three day intensive course on Segmental Lining design. He went thoroughly through every detail regarding the design, verification, production, transport and assembly of the segments forming a precast concrete ring used in shielded TBMs. He emphasised in the importance of a proper Backfilling Grouting to control the induced settlements and to ensure the correct functioning of this lining system.

Extract of the lecture of Moreno Pescara on Segmental Lining Design.

Finally this week we had the honour to presence a great lecture from Georgios Anagnostou (ETH Zurich, Swiss Federal Institute of Technology) regarding Face Stability Analysis and Design. He went dynamically through the calculation method based on the silo theory and developed by him and his research group to asses the required pressure at the face. Special attention was paid to its application to closed shield machines, certainly this was one of a kind learning experience.

Georgios Anagnostou and the students after his lecture on Face Stability.

Week 12: Getting into Mechanised Tunnelling

Starting with the second modulus of the Master Course, Professor Peila held an introductory lecture on the overall aspects of mechanised tunnelling. He provided us with a clear picture of the developed technology and its main features in order to be prepared for the following lectures from specialists on the topic.

We had the honour of receiving a lecture by Prof. Dr. Kalman Kovári in which he adopted a practical approach to introduce us the aspects to take into account for different tunnel design cases. This interactive lecture was absolutely fruitful to apply and expose the concepts and ideas that we learnt in the past. From his wide experience he proposed some case studies to enhance our critical thinking of the possible solutions to overcome complicated conditions.

Prof. Kalman Kovári and the group of students after his lecture.

Prof. Dr. Nuh Bilgin (Istanbul Technical University) held an outstanding two day course on Cutting Tools and Excavability prediction for Mechanised Tunnelling. He went through the different tool types and its field of applicability, considering also their particular wear phenomena. Main attention was laid to the performance prediction in terms of Net Cutting Rate considering several numerical examples from true cases.

Prof. Dr. Bilgin and Master's students after his lecture on Cutting Tools.

To conclude with this first week of the second modulus, Eric Leca (Arcadis and ITA Executive Council Member) gave us a very interesting lecture on Tunnelling Induced Settlements. Starting from the governing theories with concepts such as the Volume Loss and its sources, he presented the factors to be taken into consideration for a proper tunnel driving in urban areas where the constraints are maximum. A valuable discussion of the monitoring results obtained in some case studies was the way to apply the concepts learnt, resulting in an exciting discussion.

Prof. Eric Leca and the students after his lecture on Tunnelling Induced Settlements.

Week 9 & 10: End of the First Modulus

We reached the end of the first modulus of T&TBMs MAS course with combination of some theoretical principles as lining structural design or risk management with several very interesting case studies.

To start with, Mirko Corigliano from ENEL Italy, covered the main aspects of Seismic design for underground structures. In most of the cases underground structures behaves properly against seismic actions due to its link to the ground and the damping effect of seismic waves with depth. It is important to consider anyway, when applicable, the seismic actions for the structural design of the lining elements in order to avoid undesired consequences such as loss of human lives or functionality.

Engineers Adriano Fava and Francesco Comba from Alpina S.p.A introduced a fantastic case study of a traffic tunnel undergoing the King's castle in Rabat, Morocco. An extremely delicate situation to minimise settlements in order to avoid any damage to this historical buildings lying on weak rocks. It is a great example of precise design and application of ground improvement and monitoring techniques.

Adriano Fava, Francesco Comba and the students after their case history lecture.

Eng. Andrea Pettinaroli held a case history lecture on Artificial Ground Freezing in Warsaw Metro. When underpassing an existing traffic tunnel a face collapse occurred even with a jet grouted arch of pipes due to the presence of a monogranular sand layer under the watertable in proximity of Vistula River. The solution applied to overcome this critical section was the use of Freezing technique, combining open and closed circuit technology they maintained the ground at around -30 °C, reaching this way the completion of a very critical section of the project.

Eng. Andrea Pettinaroli and the students of the Master after his case study lecture.

Harald Wagner (ITA AITES – EXCO Member, Consulting Engineer, Bangkok & Vienna) gave us a very interesting lecture regarding on the impact of Urbanising and the wide range of tunnelling applicability to cope with the raising demand in terms of infrastructure. He presented several case studies from his vast professional experience. 

Fabrizio Barpi from Politecnico di Torino held a fantastic two day course on structural design of composite linings, particularly focusing on the combination of shotcrete with steel ribs. He introduced the main background concepts of the structural theories to then explain thoroughly the procedure proposed by Carranza-Torres (2000). The idea is to use the equivalent section approach to distribute the forces and bending moments on each component of the section to then calculate their capacity diagrams in order to verify the safety conditions.

Fabrizio Barpi and the Master's students after his lecture on lining design.

We had the pleasure of receiving a lecture from Søren Degn Eskesen (ITA President and COWI Tunnel Chief Specialist) oriented to risk management methods. He emphasised on the importance of a thorough definition of every possible hazard to be encountered in a tunnelling project in order to have predefined countermeasures to tackle them as soon as possible and reduce their associated risk.

Søren Degn Eskesen and the students after his lecture on Risk Management Methods.

To finish with the first modulus we had a theoretical exam for the concepts presented until now. To pass the exam of each modulus is a must to obtain the final certificate of the Tunnelling and TBMs MAS Course.