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.

Week 8: Numerical Modelling approach

To start with this week we had a day combining two very interesting topics explained by experts coming from the leading companies in the sector. Firstly, Maurizio Leotta from UTT Mapei (Waterproofing Director) went deeply trough the technologies and solutions applied by his company to waterproof the lining structures. The discussed solutions are not only applicable for tunnels but also for stations and other underground facilities lying under water table or that may expect some water influence in the span of their lifetime. Some application cases were studied focusing on the details and joints between elements, because these are the main source of failure of the system that would lead to undesired situations.

Maurizio Leotta (UTT Mapei) and Students after the lecture on Waterproofing systems.

After this lecture we moved to another topic very important and it is the probing ahead of a TBM face. Thomas Dickmann from Amberg consulting company held an outstanding lecture on geological and geophysical survey applications for TBM technology. He presented some techniques used for the evaluation of the ground properties ahead of the excavation face within the advancement steps. Finally he introduced the procedure developed by his company, the so called TSP (Tunnel Seismic Prediction) to define through a low charge D&B scheme with a good detail the conditions to be encountered.

Tunnel Seismic Prediction by Amberg Company presented by Thomas Dickmann.

In the following days Vincenza Floria (Geodata Engineering) introduced the main aspects and potentialities of Numerical Modelling for underground structures design. She established the theoretical basis considering also a big amount of case studies from her wide experience in Geodata projects all around the world. Thanks to a license provided by ITASCA we were able to apply all the concepts learned by using FLAC software to solve some simple examples performing a parametric analysis on the influence of the modification of certain ground and lining parameters on the system behaviour.

This is an amazingly powerful tool for the design that must be used with skill and knowledge about its limits and background theories.

Floria Vincenza (GEODATA) after her practical lecture on Numerical Modelling by FLAC.

Week 7: Conventional tunnelling and some key concepts

Professor Robert Galler (Montanuniversität Leoben) held an amazing lecture presenting the fundamentals of Austrian approach to Tunnelling. He went from the Conventional excavation technique, taking into consideration the fundamental static behaviour of the ground, to the tendering, design and construction phases, where precise attention is laid to the responsibilities and cooperation between the involved parties. I must say their approach is very smart, not only from the excavation technique viewpoint, so there is quite much to learn from such a solid model.

Professor Robert Galler and students after his lecture on Conventional Tunnelling.

Professor Claudio Oggeri from Politecnico di Torino introduced the General Concepts of Monitoring. This is the key tool for the comparison between the predicted and the real situation of the whole tunnel project, it is also fundamental for the control of the safety and stability from the construction to the operation. Defining threshold values for each measured parameter is a must.

European Standards introduced by Prof. Oggeri regarding Monitoring Plan.

A complete day was dedicated to Concrete Technology by Mapei UTT (Underground Technology Team) experts. Cristiano Maltese tackled the durability of the material from the basic chemistry of the involved reactions, defining the main degradation phenomena and the mitigation measures that must be taken into consideration while designing, preparing, casting and curing the concrete.

Dr. Cristiano Maltese and Master's students after Concrete Technology lecture.

Carlo Pistolesi emphasised on the mix design of concrete, taking into consideration the exposure classes, the required resistance and some other particular requirements of each project to define the right proportions and composition. The conclusion is that knowing very well this material is of paramount importance in order to be able to produce the durable structures required for tunnelling purposes.

Eng. Carlo Pistolesi and the students after his lecture on Concrete Technology.

Professor Peila continued with his series of lectures focused on Ground Improvement techniques, going deeply in this occasion into permeation grouting solution. He presented the technological aspects, grouting mixtures and the design and testing procedures for a proper result in terms of continuity, permeability and strength without causing disturbances to surface structures. The lecture was combined with plenty of case history from his former professional experience as a young engineer in a grouting company.

This week concluded preparing the field for the topic of next week that will be Numerical Modelling. Professor Borri Brunetto from Politecnico di Torino held a fantastic theoretical lecture on the fundamentals of numerical methods, starting from the mathematics of continuum mechanics and going through the background theories solved by Numerical Models to obtain a computationally efficient and convergent to a good approximation solution. 

Week 6: Tunnelling applied technology

We have reached the sixth week in Tunnel and Tunnelling Boring Machines Master Course.

This week was dedicated to some tools for tunnelling excavation as Formworks, Rock Drilling tools and Mechanical Cutting equipments.

Specialised crew from CIFA (Underground Concrete Machineries) gave a complete overview of their available technology for Formworks. Eugenio Bertino introduced precast segments moulds and the different plant layouts for the production system depending on the project requirements. Later on, Giovanni Esposito completed the topic speaking about Cast in-situ formworks, explaining the principles of self supporting and self reacting technologies, emphasising on the details for a proper application at the job site.

Bertino and Esposito from CIFA and Students after Formworks lecture.

Another company that presented his technology this week was SANDVIK (Mining and Construction Tools), particularly they exposed Rock Drilling Tools and Roadheader equipments.

Juha Kukkonen dedicated a complete day to Rock Drilling machines and tools produced for tunnelling and mining applications. Jumbos for D&B excavation, Bolting units and Extension Drilling equipments were treated in detail, analysing the control systems of the machine that ensure the best possible results in terms of production and final product.

Juha Kukkonen from SANDVIK and Students after Rock Drilling Machines lecture.

Thomas Peinsitt presented the whole catalog of available products for Mechanical Cutting equipment, focusing mainly on Roadheaders. He went through its mechanical features, cutting sequence, cuttability parameters, wear phenomena and finally safety and ventilation aspects. Thomas shown the potential of this rarely applied technique through many case studies.

Thomas Peinsitt (SANDVIK) lecture on Mechanical Cutting and Roadheaders.

To conclude this week Director of the course Prof. Daniele Peila held a very interesting lecture on soft ground improvement techniques as forepoling, face reinforcement, drainage and jet grouting, describing deeply their particular features and design procedures. Great part of the lecture was reserved to case studies from his professional experience in order to understand the wide range of possibilities available to enhance the properties of the material to be excavated and guarantee safe and stable working conditions.

Professor Peila lecture on Ground Improvement.

Week 5: Excavating and supporting rock masses

Last week in Tunnelling and Tunnel Boring Machines MAS course was focused on two wide conventional tunnelling fields as Drill and Blast excavation technique and first phase support for rock masses.

Dr. Daniele Martinelli (Rockplan - Politecnico di Torino) introduced the D&B technique, from explosives and detonators to the design of the whole blasting scheme. Another key concept is the management of blasting induced vibrations to avoid disturbances to surface structures. From his wide experience in Baltic hard rocks excavation at Rockplan (Finnish rock structures design company) he presented some practical examples and exercises to reassure the concepts.

Dr. Martinelli and Students after his lecture on hard rock excavation examples from Rockplan. 

Stefano Airoldi from Orica explained the technology and field of applicability of the bolts produced by his company, merging the theoretical concepts of each type of bolt with his background from a large career in rock improvement technique. Dr. Martinelli proposed a calculus example for bolting technique and same case studies. 

Orica bolting technology presented by Stefano Airoldi.

Dal Negro Enrico from Mapei (Construction Equipment Supplier) held a fantastic lecture focused on sprayed concrete for first phase lining applications both for temporary and permanent solutions. He presented dry and wet mixtures technologies focusing mainly in the latter as it is the one applied in almost 95% of the cases.

Sprayed concrete technology presented by Mapei UTT leader Dal Negro Enrico.

 Two experts from Bekaert Maccaferri (De Rivaz, Benoit and Rossi, Bruno) gave an outstanding presentation on the use of fibre reinforced concrete technology for tunnelling applications. Cast in-situ final lining, Precast concrete segments and last but not least Sprayed concrete are the main field of applicability for this innovative solution that provide fantastic performance, faster and safer working conditions than conventional steel reinforced concrete. 

De Rivaz, Rossi and students after the lecture on fibre reinforcement for tunnelling applications.

Finally Dr. Martinelli presented the concept of grouting for rock masses combined with several practical examples from his own experience at Rockplan company. Some time was given also to a case study of the approach taken by the company to some very interesting projects as metro tunnels and a nuclear repository in Finland.

Rockplan rock structures design case studies presented by Dr. Martinelli.

Week 4: Getting into Tunnelling

In the past week at T&TBM Master there was a combination of very interesting lessons held by high level professors that resulted in a great learning experience.

On Monday, directly from Lyon, Robert Galler (Montanuniversität Leoben) gave a video conference lecture for three simultaneous spectators: T&TBM Master's students at Politecnico di Torino, a University board at Paris and face to face with Master's students at Lyon (Tunnels et Ouvrages souterrains). 

The title of the lecture was Sustainable Tunnelling - Focus on Resource Efficiency and it was part of an experimental video-lecture approach being investigated as the future of training courses, conceived mainly for emerging countries with short access to specialised tunnelling education.

Robert Galler's video conference lecture from Lyon seen from Politecnico di Torino.

The quality of the lecture was perfect, interactive questions from each of the parties were really useful so finally feedback of the students was very positive from this experience.

The following lecture was held by Eng. Piergiorgio Grasso, president and founder of GEODATA Consulting and ITACET foundation Vice President. There are few words to say about such an outstanding professional, and his lecture on Layout Parameters for the Design and Risk Management in Tunnelling was a proof of it. Definitely one of the most remarkable lectures to learn from the experience of today's leaders in tunnelling industry.

Students and Eng. Piergiorgio Grasso after his lecture at T&TBM's Master Course.

Geologist Lo Russo Stefano from Politecnico di Torino provided a lesson on the fundamental aspects of water control in Tunnelling projects. He merged some basic concepts of hydrogeology with his professional experience from several big projects involving water resource management. Special remark was the need of searching smart solutions to overcome underground in-rushes treating the water as a resource instead of as a problem.

Stefano Lo Russo, Hydrogeology in Tunnelling lecture's.

Finally the director of this Master Course Professor Daniele Peila introduced the fundamental concepts of support techniques both for conventional and mechanised tunnelling. Special attention was laid to the design phase of first phase supports through empirical, analytic and numerical methods. The remarked concept by Prof. Peila was that none of the results of these methods should never be taken as a closed solution for any problem, instead we must consider the specificity of each project merged with the constructor experience.

A special opportunity was the visit to the Tunnelling and Underground Space Centre (TUSC) Laboratory at Politecnico di Torino. At this incredibly modern research centre several tests for Tunnelling industry are carried on mainly on Soil Conditioning for EPB, Wear tests, Extraction tests and some other innovative research devices are tested to model the reaction of the ground to the mechanised excavation process. We had the opportunity to presence some tests carried out on bicomponent grouting mixes for backfilling purposes. Special thanks are given to Eng. Carmine Todaro who introduced the main properties of this material and its characterisation process.

Eng. Todaro, Students and Prof. Peila at TUSC Research Laboratory.

Week 3: Rock mechanics week

The third week of T&TBM's Master course have been fully dedicated to study the main concepts of Rock Mechanics. Special emphasis on characterisation and modelling of rock masses, taking into account intact rock and discontinuities properties was laid.

Professor Monica Barbero from Politecnico di Torino covered three days of both practical and theoretical lectures with a fantastic didactic approach. After introducing the most important concepts for the characterisation of rock masses she presented some stereonet examples (hand drawn and with DIPS software) for the analysis of the possible kinematisms within the tunnel profile.

Kynematic analysis of an example presented by Prof. Barbero using DIPS software.

Following with the rock mass characterisation process, Dr. Giordano Russo from Geodata Engineering held a formidable lecture on Geomechanical Classification methods. From the first Terzaghi's approach (1946), following with Deere (1964), Bieniawski (1973), Barton (1995), Palmstrom (1995) and Hoek (1995) as the most widespread criteria in time he reached the actual approach applied and developed by Geodata company (GD Classification, Russo et al. 2007) shown below.

Master's students and Dr. Giordano Russo after his lecture on Geomechanical Classifications.

GD Classification for the characterisation of excavation behaviour (Russo et al. 2007)

Concluding this third week we visited the Politecnico di Torino Geotechnics and Rock Mechanics laboratory DIPLAB (DIsaster Planing LABoratory). Dr. Oronzo Pallara as the Technical Director of the laboratory conduced the visit introducing the available testing devices. From Direct Shear Devices, Oedometers, Uniaxial compressive presses, Triaxial apparatuses, to many other specialised devices for research purposes and for the laboratory characterisation of the soil, intact rock and discontinuities are available in this fantastic and modern laboratory.

Students, Professor Monica Barbero and Dr. Oronzo Pallara after the visit to the Politecnico laboratories.

Professor Monica Barbero and Dr. Oronzo Pallara introducing the laboratory to the students.

Dr. Oronzo Pallara explaining to the students the triaxial tests at soil mechanics laboratory.