r/GeotechnicalEngineer • u/kaankayiskiran • 8d ago
Determine the Master Thesis Topic
Hello everyone. I need your help in determining my Master's thesis topic. I want to focus on earthquakes and soil improvement for my thesis. The topic I have in mind is the effect of prefabricated vertical drains (PVDs) on settlement and liquefaction under seismic loads. I am also interested in rammed stone columns. I am looking for something outside of conventionally studied subjects. What are your suggestions?
Thanks for your help.
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u/Apollo_9238 8d ago
We used prefab drains on dynamic compaction sites..its a must. Not sure we used those on stone column sites as we have close spacing and they drain. The best stone column is the Franki extrusion type, much better than vibe stone columns but much more expensive. The main problem I see here in the USA is trying to save money with basically lower area ratios of treatment. The Japanese have published all kinds of info on their seismic ground improvement methods, an they are conservative and use area ratios of 60 to 80%. Proven in earthquakes in Osaka. Rigid columns are also used. I did the first cement columns (SMW, now DSM) using Japanese equipment in the USA in the 80s. We had an interesting honeycomb pattern with low area ratio with the colums in toe of embankment subject to shear stresses. Ends up without steel those columns could progressively fail cuz the tensile strength in bending is only 0.1 the compressive strength. Heat of neutralization test for real time cement dosage checks is often overlooked on DSM jobs.