How to Teach a Tunnel Course?

Being a student sitting in front of a black- or whiteboard is well known for many of us. The teaching-learning environment is diverse and can take on multiple facets, such as taking in information as a passive observer, working towards a learning outcome in group work, like discussions or smaller questions to be answered in pairs, or as a student-led lecture by learning-doing-teaching. 

Creating the content for any subject to teach, in the contrary, is not so much known by most of us. And thanks to the department of civil and construction engineering at Oregon State University (OSU), I am able to learn how much work teaching really is and how gratifying it feels once the “comprehension spark” happened - at the student level, as well as at the instructor level.

Currently, I am instructing a specialty topic course on tunnel design and construction. Asking myself what the students should get out of the course and how to accomplish this was difficult, especially for my first course. 

Tunnel Uetliberg, Zurich, Switzerland (image: Amberg)

I remember my first tunnel visit vividly. I had been on a week-long workshop about tunnel construction, ventilation, and muck transport and was able to visit the Uetliberg tunnel in Zurich, Switzerland. I hadn’t had much knowledge about tunneling, but being down there in the dark, carrying this large fanny pack with something very heavy in it, with those super large steel-toed rubber boots, and feeling so small and invisible compared to the diggers and machines, partial spot lights and loud sounds... I knew back then that it this is a fascinating world to me. Well, I did my Masters on the dynamic behavior of a pedestrian bridge, but jumped right into the opportunity of tunnel engineering during my first job and studied some more tunneling at the ETH Zurich while working full time. So, what is it I want my students to get out of this tunnel course? I hope for an interest in underground work in general - yes, with some background knowledge - but what I really wish for is a spark in their eyes. If the interest is not there, no learning will happen. If a subject is exciting, learning will happen with seemingly no effort.

For the preparation of the course itself, I’ve learned that talking to experienced teachers and professors who’s teaching style I liked was immensely helpful. Further, I asked myself what details from my own student experience I remember and which of them I remember because I liked them. I am trying to implement those positive details into my weekly lectures. Also, I took an Engineering Education class two years back at OSU and reflected a lot over my notes, even used the basis of the then created syllabus and my “mini-student-led-lecture” on tunnel boring machines (TBMs) in the actual tunnel course. I was reading the books "The Courage to Teach" by Parker J. Palmer and "Making Learning Whole" by David Perkins which helped me, too. 

For writing and grammar, I think it is unavoidable to get some help, especially for a non-native English speaker. So came "The Elements of Style" by W. Strunk Jr. and E.B. White and "Keys to Great Writing" by Stephen Wilbers into play.

I can say it now: I was not prepared for the large amount of work I had to put in to obtain a for me satisfying class environment and lecture outcome. One hour of lecture takes me about 8 hours of preparation and post-work, including creating course content, worksheets for during the course time, home work assignments and their rubrics with an example solution to stay objective, obtaining visuals from books or videos, or to give written feedback on the assignments for each student. 

All in all, “Hut ab!” (Hat down) to all teachers, instructors, and professors, as we say it in German to someone who is or was doing intense and ingenious labor with a surprisingly great and elegant outcome. The teaching profession deserves much more applauding, especially for extraordinary work.

In addition, I am extremely thankful to industry connections and partners to support tunnel classes at universities with guest lecturers and support for field trips. It is very exciting that two handful of students are able to go to Bellevue, WA to visit an ongoing tunnel excavation and construction for the East Link Light Rail metro connection between Seattle and Redmond. The excavation is scheduled to be completed very soon. (I will report on the site visit with many pictures and interesting views in my next entry —> so hold your eyes open!)

Until next time.

Yours,

Stephie

Tunnel Short Course, Golden, Colorado

Tunneling Fundamentals, Practice, and Innovations

End of June 2016, I was able to attend the annually offered Tunnel Short Course at Colorado School of Mines. This course stretches over four days and includes presentations from professional engineers, designers, contractors, and governmental agencies like L.A. Metro or Sound Transit from Seattle, WA in addition to hands-on labs each afternoon.

During the presentations, each aspect of tunneling was talked about - starting with how to choose the right excavation method, over risk management and site investigations, to tunneling in hard rock and in soft ground, with the finish about planning, safety and cost estimation. The hands-on labs in the afternoon were a welcomed break from all day sitting and I was able e.g. to execute an abrasivity test on rock which includes a pin, a small piece of rock which is scraped once for one second with the pin. Then the pin has to be analyzed with a microscope to measure the wear of the pin tip. The measurement can then be taken to compute an abrasivity number which indicates the hardness of the rock - 10 is very hard and 1 is very soft rock.
Other hands-on labs were all about rock cutting tools which you can find in front of tunnel boring machines, or all about shotcrete or soil conditioning for EPB TBMs
(earth pressure balance tunnel boring machines for soft soils).

Overall, this course is great for tunnel fanatics and those who like to be one.

Thanks for "reading in" and until the next time.
Stephie


Here are some impressions from the course and the labs I attended.
(f.l.t.r. Cutter head of a small TBM; Different cutters from "old age" to now; Geology trail - sandstone rock with layering; Presentation about TBMs; Different ground support systems - Shotcrete applied on steel mash, Steel ribs.)

World Tunnel Congress 2016 in San Francisco, CA

Lucky me!

If you are one of my regular readers, you might recognize the words: world tunnel congress. Yes, I attended the congress in 2013 in Geneva, Switzerland and I wrote about it in several articles (link May 2013, link one and two of June 2013). I went with my former co-workers and we were making jokes about going to the San Francisco congress in 2016 since I will be living there anyway... Well, guess what? Okay, I am not living in San Francisco at the moment, but only an hour of airplane travel away and I was able to attend this great congress in April this year.


16th World Tunnel Congress, San Francisco, CA, USA
April 22 through 28, 2016

What was my purpose of going?
My purpose this time was mainly to connect with people in the field of tunneling, people that might be of help for my doctoral research - Tunnel crossing Fault zones - and to meet with people my academic adviser Dr. Scott Ashford connected me with. Secondly, I wanted learn about the subject of tunneling in earthquake prone areas.

How did I accomplish my purpose? Who did I meet and why were they important?
I actively engaged with industry groups, engineering companies, spoke with Professor Mooney from Colorado School of Mines, who will support me as an adviser in tunneling and who advertised the tunneling short course (you will hear about it in my next blog article). Further, I listened to interesting topics and obtained further connections with Japanese engineers and had follow-up emails about Japanese literature about tunneling in earthquake zones including fault lines. 

What did I learn in general?
Through conversations with engineers from academia and industry, I learned that the subject of tunnel crossing fault zones is a very exciting subject of the future. And most of the tunnels constructed through fault zones are not constructed with an fault offset in mind. The main method of mitigation today is closure of the tunnel and reconstruction.

Who else did I meet?
Surprisingly, I met engineering friends from the time when I worked in Switzerland. And I met with a newly organized group of Women in Tunneling who held a meeting. I am hoping to be able to contribute to this group of female engineers.

And what am I doing now as a result of me going?
I am more and more convinced that my research subject - tunnel crossing fault zones - can answer or at least can start to answer questions many practicing engineers would like to know more about.


Wish me luck in my undertaking!

See you next time.
Stephie

Tunnel in sandy soil

Hello everyone, in this post I am going to answer two other questions I got during the my tunnel lecture.

• How does the method of creating a tunnel change when tunneling through sand?

• Sand is a completely different material compared to hard rock. Building a tunnel through sandy ground could mean several things:
• Ground water and surface water could have a strong influence
• Collapse of tunnel face could impact the surface by building a deflection
• More direct load from above, especially when building shallow
• Positive attributes might be:
• Minimum gap between the outer tunnel lining and the soil surrounding the tunnel - positive interface interaction between tunnel and soil
• Grouting is easier and more successful in sandy ground - but, on the other hand, the grout might go anywhere or gets lost when the pores between the sand grains are large enough.
• The construction of a tunnel through a sandy ground can be done with a conventional excavation in several steps, like heading and bench method or NATM, with immediate support of the face and the tunnel walls. 
• Other options are possible. It all depends on the building site conditions and the contractor how they build tunnels in similar ground before and with what they are comfortable and professional at the same time.

• Cost effectiveness of crating a base tunnel compared to a raised tunnel, material removal, tunnel type (for trains, cars, utilities), aesthetic, ...?
• The effectiveness of a tunnel is strongly coupled with economics like an increase of train speed which results in less time traveled, which will give the people more time for meetings, work, etc.
• Further, the effectiveness is coupled to ecological considerations, like the environmental impact - a base tunnel might have less of a "surface"- impact than a train route partially above the mountain.
• Security during the service is a highly discussed subject as well - for instance, a base tunnel might have a higher risk of fire due to its length than a tunnel which lies higher in the mountain and is shorter for that matter. On the other hand, the road to get to the higher point at the mountain might be riskier, the train/car/truck has to slow down, possibly windy road...
• The older train routes above the mountains might be in very good condition and worth keeping, while others might be outdated and have to be replaced.
• The construction itself has its influences, e.g. the material transportation, concrete fabrication, dealing with excavation material, pollution during construction, and so on.. and a generalization cannot be made, it all depends on the specific project parameters.
• Since the tunneling industry advanced so rapidly in the past decades, I believe that more base tunnels are possible. This would reduce the noise emissions and environmental impact on the "surface" and creates a faster and maybe more secure option for the economy.
• To rap it up: it is hard to decide which one is more cost effective. Other factors might be as or even more important to the owner, the immediate population, and to politics. Large traffic projects, like tunnels are, have almost always political influences which could alter the cost effectiveness dramatically.

So, I hope I could answer - or not answer - the questions.

Please, correct, add, or otherwise comment on this. I am always eager to learn new things and to correct "old" views.

Thank you for reading.

Stephie

Summary of the 6th International Conference on Earthquake Geotechnical Engineering - 6ICEGE

What can I say about this outstanding conference?
The name alone speaks thousand words - Geotechnical Earthquake Engineering, and everybody who is internationally involved in this subject was there, attending the conference, participating in presentations, posters, and the exhibition. The program was so dense, the committee had to organize the conference in four parallel sessions each morning and afternoon over four days. And each session had their invited guest speaker of international importance. It was just an abundance in cutting edge knowledge presented.


But how can I summarize this vast amount of happenings?
Let me start with the conference city: Christchurch, New Zealand, where severe liquefaction took place during the Canterbury Earthquake Sequence in 2010/2011. 
The earthquake magnitudes reached up to Mw 7.1. The aftershocks were as devastating as the main events with magnitudes ranging from Mw 5.3 to 6.3. The city's central district simply collapsed and is under construction until today. This was the perfect venue for a conference of this order. 

Destroyed Church, Central District of Christchurch, NZ

The general public is informed after all what happened and even my taxi-airport driver naturally knew what lateral spreading is and asked me if I have had seen some of the affected places here in Christchurch, which I did by the way. The taxi drivers comment gave me a smile and reminded me of the speech the major of Christchurch gave at the beginning of the conference. She said that the work of an geotechnical eathquake engineer is very much important and supports all there is in a city! Thank you, major, for saying it out loud! This made us all feel acknowledged and supported in our work.

Back to the conference: I was particularly interested in this conference and the city where it took place because my own research interest in liquefaction. Other conference subjects, besides soil liquefaction, lateral spreading and their mitigation, were about specific case histories including Nepal, numerical modeling, soil-structure-foundation interaction, site effects, retaining structures and deep foundations, and many more.

I also enjoyed very much the possibility to meet new people, well known professors, like Misko Cubrinovski, who was the chairman of this conference and is a professor at the Canterbury University in Christchurch and one of the leading researchers in the field of liquefaction. I met other participants from the industry like Paul Somerville, one of the leading seismologist for subsurface ground-motions and shear-wave velocities, and I met other graduate students from well established universities around the world, e.g Christchurch, Vancuver BC, Perdue University, UC Berkeley, and others. Also, I was eager to learn about the Nepal Earthquake and took advantage of the complete Nepal session.

OSU Group at the 6ICEGE in Christchurch, New Zealand
From left to right: Scott Ashford, Michael Olsen, Stephanie Lange, 
Daniel Gillens, Ben Mason, Armin Stuedlein, and Kengo Kato

After the conference, the organizer offered Technical Tours. I attended a Technical Tour with the subject of slope instability and remediation on the Port Hills in Christchurch, which were hit hard by rock fall. The tour showed clearly that the temporary security measures - mainly shipping containers along roads and rock faces - were successful. Even the central district of Christchurch uses modified shipping containers for its shopping mall, which is a tourist attraction nowadays.
Four years after the last earthquake event, the city is still building itself up. The conference center downtown is not finished yet, so the conference took place at the Airforce museum - that is why there is an airplane in the background of our Oregon State University - OSU group picture.

In short, I can say that the conference was a total success in terms of learning new things and in terms of social networking.

After the conference was over, most participants took some days off to see some of New Zealand's beauty. I did my New Zealand travel before the conference. And here are some of my impressions.

Personal Impressions of New Zealand, October 2015

New Zealand is a nature's paradise with small windy roads, gentile green hills, harsh mountainous regions, and calm fjord-lands. And anybody how loves nature, birds, and volcanic activities, has to have New Zealand on his or her must-see list.

Why re-reading articles makes so much sense...

Hello there,

if you are like me - busy with so many to-do tasks - and having to start over to read some journal articles, because the last time you started to read this particular article, you stopped for some reason and forgot what it was about, then I have a solution for you, at least this solution works well for me:

For me, having to start over this 40-pages long article about sinking/ floatation of pipelines for the fifth time felt very much demotivating. But I know that this paper is going to be influential for my research. So, I really want to know what it says!

So, what needed to change?

Well, I sat down and thought about what I want to accomplish with my research and what part could this particular author contribute to. After I had done this, I started to read this paper with a different aim: I am taking additional notes on a totally different subject - what to look out for for the setup of physical experiments - as well as the main content.

And this gave me a moment of realization yesterday.
Journal articles are so dense in their content, due to the limited number of pages, that reading it a second time with a different point of view might open up new possibilities, new directions, and might contribute to your work in a totally different way.

I am so excited now to read further in this wonderful article - a pleasurable "candy reading"!

Thank you for listening!
Yours, Stephie.

Tunnel and earthquakes?

Hello everyone, as I mentioned in my last post I am going to use my blog here to answer questions I got during my tunnel lecture I gave last fall.

• What are types of tunnel earthquake reinforcement?

• To reinforce an inner tunnel lining the "normal" structural reinforcement bars are used. I put "normal" in quotation marks because the tunnel reinforcement has specific connection types, main bars in cross section are curved, and often tunnel linings are build segments of about 10 m or 30 ft in length so each edge has terminal bars.
• To get to the question against earthquakes: it depends. Building a tunnel in the ground goes along with a positive behavior against earthquakes - the ground shakes and it is assumed that the tunnel goes with the same movement.
• Challenges are at points of transitioning from a softer soil to, let's say, a hard rock. These points should receive the attention. A similar but more severe subject is the crossing of a fault line, e.g. the water mains in southern California cross the San Andreas Fault.
• Well, how do you build a tunnel at these difficult points? That is a difficult question to answer in just one blog article. It is less about reinforcement and more about the whole design of the tunnel. In March last year (2014), I attended parts of the Tunneling Class with Prof. Sitar at UC Berkeley as a guest listener and a representative from Jacobs Associates presented on the Claremont Tunnel with a diameter of 2.7 m or 9 ft crossing the Hayward Fault line near San Francisco. They constructed a pipe inside a tunnel that can withstand a lateral offset of 2.6 m or 8.5 ft. The whole project of seismic improvement costed $38 Million! Not every water department has such an amount for a seismic upgrade, but a loss of the main freshwater line would cost more after an event. For a more detailed description, the following two pictures have links below them.

Claremont Tunnel Design - Fault Crossing

Claremont Tunnel - Jacobs Associates

The subject of building tunnels across faults is very present and each solution is unique and innovative. And at some places, like L.A. and the San Andreas Fault with an estimated maximal offset of 7 m or 20 ft, solutions do not exist yet.

Thanks for "tuning in". If you have questions or comments, please contact me.

Stephie