Flogging Dead Horse - Thesis topic

[EireChch]

Hi all,

I know this this topic pops up occasionally but I will flog the dead horse and ask the question again. I am going to be starting a MSc course – civil engineering with geotechnical engineering in Sept 2016. I would like to get a head start and have a good idea of what my thesis topic will be. Maybe even make a start on my literature review.

I am very passionate about geotechnical engineering. I have roughly an hour commute each way on the train and I would regularly just print off a paper on something piling, slope stability, ground improvement. I find myself interested in piling and rock socket design. As part of any thesis I would do I would love to undertake some physical testing/monitoring i.e. sticking some transducers/accelerometers on a pile or something of the likes. A college of mine prepared a thesis on “Experientially derived relationship between undrained shear strength and Driven Pile Sets” where he had borehole data and pile driving information on a number of jobs that he had worked on. He correlated what shear strength would be required to achieve the final driving set. It was very interesting. It is available free online if you google the title.

The advantage he had though was that he was the Director of the company so access to all this information was relatively easy. He probably had a good working relationship with the piling contractor too. I am not working for a geotechnical company at the minute so it’s a little bit harder to access information like this. I would have to go begging cap in hand to a driller/piling contractor and hope that I get the right guy that would be willing to help. Also, telling a piling contractor that I want to monitor some of his pile instillation may not sound that appealing to him. I doubt they would like another pair of eyes looking over their shoulder. Alternatively maybe they would welcome additional QA?!

I think I would also like to include some portion of FEM in my thesis. Almost all geotechnical jobs I see these days require the applicant to be able to use the likes of PLAXIS or OAASYS etc.

I’ve seen some thesis’s that review a lot of literature. For example recently I read a thesis that compared all the slope stability methods Morgenstern price, bishop, spencer etc. While I feel a thesis like this would be worthwhile as it would make you very competent/knowledgeable about the methods, I am a hands on person and would prefer something with a bit of hands on work involved. Something that would require analysis of raw data.

Any advice or ideas would be appreciated. Also, when the time comes around I would be happy to share my thesis those interested. Heck, I could even have a few Eng-Tips thesis advisors. Ron, Fd, OG….interested ? 

I will post again when I finally decide on a topic and those that are interested can let me know!

Cheers
ECh

 

[fattdad]

Where you going to college? I love my career!

f-d

ípapß gordo ainÆt no madre flaca!

 

[EireChch]

Thats great. Where abouts did you study and where are you working now?

Im an Irish boy living and working in London at the minute. I will be heading to University of Portsmouth in Portsmouth, south east coast of England.

 

[oldestguy]

Look up the comments for a similar question in the Civil Engineering Other room.

 

[fattdad]

I'm in Virginia. Studied geology at Colorado State University and geotechnical engineering at Virginia Tech. I was in consulting for 30 years. Now I work for the state highway department.

f-d

ípapß gordo ainÆt no madre flaca!

 

[oldestguy]

An advantgage I had back then was a scholarship by a well known supplier of culverts and related highway appurtances. I used their donated material and got the county highway dept to install it free. If a similar situationcan be develped, it will make everything much easier.

 

[BigH]

I think oldestguy (as usual) hit on something that can be quite important. Why do you not go to a foundation contractor - or even a general contractor and find out what soils issues bother them the most in their work. And how does this affect their work methods and, importantly their bottom line. What would they like to see in the geotechnical design report (put out by the geotech or the drawings by the structural engineer) that would help them increase their efficiency and cost margins. Typically one might consider that it is groundwater - or excavation support (PEinc??).

Getting this information from them and then putting together a "business plan" that might show them how you and your research could help them in their work/bottom line - might very well lead to them helping you with some experimental assistance - as well as opening up their vast knowledge.

One of the very important geotechnical issues is not necessarily the "design" but how the design effects construction. Improvements to design for the sake of construction rather than for the sake of a more "elegant" design.

 

[SlideRuleEra]

I find myself interested in piling...

As a former bridge contractor, I can suggest a topic. In certain soils, part of the "art" of driving timber piles is taking fast, real-time action to keep pile tips from brooming during driving. Some specifications do not allow for this quick, subjective decision making flexibility. Every pile is point-bearing during driving, even if it is designed to be a friction pile. During driving, stress on the tip's wood fibers is absurdly high. A broomed timber pile has essentially no point bearing capacity, but determining if a pile broomed is tricky. I dare say that more timber pile supported structures fail from overdriven piles than from underdriven piles.

Come up with a way to put "science" into when and how to predict timber pile tip brooming.

Much timber pile driving is small-scale, low-cost, low-tech... no budget for metal pile points, PDAs, or index pile test programs.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[EireChch]

Thanks for the responses gentlemen.

F-d : how do you find working for the state compared to consultancy? Less stress or more stress?! Also, fyi – over here in the UK/Ireland, if you complete an honours (4year degree) or master’s degree, you can get a one year working visa for the US after you graduate. I’m planning on taking this offer up when I graduate in June 2017. I might give New York a shot.

Big H – that’s a great idea, I will definitely follow that up. I might draft up an email along those lines and send it out to a few foundation/piling contractors and see what comes back! I will keep you updated on this thread.

SRE – again thanks that’s another good idea. Could maybe look something like driving a timber pile into a dense gravel layer. Just thinking out loud now but If the pile is driven within a 1m (horizontally) of a known borehole that has encountered say a 3m thick dense gravel layer (SPT N60 of 30 +maybe) at a known depth. From researching online it appears that anomalies in pile driving i.e. large penetration with one blow etc or piles rotating/running off vertical are the only signs that indicate if a pile has split or “broomed”. Monitoring pile driving at the depth of when the gravel layer was encountered could potentially give tell-tale signs of when brooming has occurred. Could also drive a timber pile with a steel shoe on it and compare the data. Driving the crap out of a pile then extracting the pile completely out of the ground to examine the tip could be another option but not sure exactly how feasible that is?

If I managed to get a piling contractor on bored I could hopefully get them to drive a timber pile at a site they were working on. They may already have a PDA guy organised to test working piles so testing one additional timber pile would not be a much of a deal if they were to get a thesis out of it.

My only thought would be that in my limited experience timber pile driving is generally more utilised in light weight timber/residential type structures? Precast concrete, bored concrete or steel piles would be a lot more common?

 

[SlideRuleEra]

Driving the crap out of a pile then extracting the pile completely out of the ground to examine the tip could be another option but not sure exactly how feasible that is?

That is very possible. On one project the contractor was driving point bearing timber piles per spec. Piles would stop briefly, then resume movement - we suspected brooming. Had the contractor drive five piles to different terminal blow counts (if memory serves, 2, 3, 4, 5, and 6 blows per inch). Extracted all piles. Only one was not broomed, 2 blows per inch. This became the new driving criteria for that project.

You are right about steel and concrete piles being more common. In the southeast US, timber piles are still used frequently for many structures. This has to do with the availability of southern yellow pine, poor soils, and low-rise buildings.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[Okiryu]

EireChch, if PDA/CAPWAP analysis is available, you can explain to the Contractor that doing this test will save some money to them(you can reduce FOS-so you can get higher capacities, if you allow for dynamic testing for QC operations), and they may be interested and support you. That could be a thesis topic, as well. Recommend get papers from Van Komurka which shows how dynamic testing can improve on the economics of piling activities.

 

[EireChch]

Just an update.

BigH - I have emailed 3 foundation contractors and received two responses of not interested and one that hasnt got back to me yet. I was a little disappointed but not surprises to be honest. I think contractors might be a bit wary of someone coming in and supervising etc. Anyways i will try another 3-4 contractors and hopefully something might come back.

An engineer in my office gave me a good recommendation - he said to get to look up the professors that will be over the masters as these will have published papers etc in the past. Two of the professors seem to specialise in slope stability topics along with some pore pressure monitoring data. I also found out that as part of the course there are regular field day trips to the Isle of Wight. This is a small island of the coast of south England, close to France too. The southern coast of the Island is very susceptible to landslides. In the past 200 years there have been over 300 landslide events. An extract from a paper describing the islands geology below.

INTRODUCTION TO THE ISLE OF WIGHT INSTABILITY STUDY AREAS
The geology of the Isle of Wight is complex, the sedimentary rocks having been uplifted,compressed, folded and faulted over geological time. The processes of weathering anderosion and particularly the impact of rising sea-levels since the last Ice Age have resulted in aunique assemblage of geomorphological features within the relatively small area of the Island.As a result the Isle of Wight forms an ideal location for study in the context of coastal change,climate and instability.The Isle of Wight instability sites have been selected because of their variety and for theirdemonstration value in terms of the way that problems have been addressed as well as thevariety of circumstances involved and solutions being implemented. The sites comprise theSandown Bay cliff line on the south-east coast of the Isle of Wight between the towns of Sandown and Shanklin, the Isle of Wight Undercliff and particularly the town of Ventnor, and theAfton Down section of chalk cliffs on the south-west coast of the Isle of Wight near Freshwater.Within the Ventnor Undercliff more detailed discussions of particular problematical location are described following an introduction to the Undercliff itself, which comprises the largesturban landslide complex in north-western Europe. The study areas within the Undercliffdemonstrate the approach adopted by the Isle of Wight Council in terms of investigation,remedial works, where appropriate, and ongoing management of the landslide itself. Geotechnical Study Area G1 Ventnor Undercliff Landslide Complex

I was also considering a slope stability topic too so I am happy that the course might provide some very good modules on the topic. I could potentially do something relating an inground palisade wall to prevent some type of minor landslipe/slope failure.

 

[EireChch]

An update for those who are interested.

I have emailed four piling contractors to see if they encounter any day to day problems which would require further examination. They are not interested for one reason or another. So I have came to the conclusion that I will not be able to undertake any large scale physical modelling a pile foundation. It may have been a bit optimistic on my behalf.

After some research I am now interested in undertaking some scaled modelling of a pile foundation. I have read a paper that discussed the development of a MIDOS pile foundation. MIDOS = MIxed Drilled Offshore Steel. This was developed mainly for use in calcareous sands where pile driving can cause contraction of the sand particles which significantly reduces frictional resistance. A paper on the topic is attached.

The authors created a 1/50 scaled model in a 1m x 1m x 1.5m deep sand box. 40mm dia grouted piles 800mm long.

I was thinking about doing something along the lines of preparing two sand box models as above. One with Calcareous sand and one with your typical silica sand. In each box i would place 4 piles. 2 grouted piles and two driven piles (not sure yet what type of driven pile, it may have to be a hallow, closed end circular pile as this would be easier to make than a small H or concrete pile).

I could look to undertake two compression tests and two tension tests and do a comparison and draw some conclusions.

The issues I see after an initial assessment would be driving the scaled pile to reflect full scale driving and also the amount of measuring equipment I would need. I know the Uni will have some but i am not sure how much!

Any thoughts, comment or criticism welcome.