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I am being asked quite often on why do I look at the geotech earthquake engineering research whereas New York city is located in an area of low seismicity. 

I was not involved in earthquake engineering research until I started teaching soil dynamics in 1994. 'Dynamics' is at a level higher than 'statics' and in many cases the dynamics problems should degenerate to the static problems when the earthquake terms are dropped.  Research wise, we should be leading the cutting edge, and in many cases, earthquake engineering problems are confronting us. New York City did not require seismic design but the Building Code has been amended several years back for a compulsory seismic design. Thus, our research topics are never limited to local conditions - we are responding to the global needs. My research interests are never limited to those presented in this home page; in fact they started to get old when they appear here.

If I may quote an example, the Kansai area in Japan, which comprises of Osaka, Kyoto and, Kobe, was considered to be of low seismicity although historical records indicated that severe earthquakes had occurred in Kyoto a few hundred years ago. While most people felt that the earthquake is the business of Kanto people, the worst earthquake occurred in Kobe. The situation of the East coast versus the West Coast is simialr to that of Kansai versus Kanto. The few hundred years of history that we are trying to remember is never long enough to cover the geological age, or to give a clear picture of what will happen to this earth crust.

But my topics of research are not limited to earthquake engineering problems....

Note: after the Virginia earthquake (M=5.8) of Aug 23, 2011 and its shaking around New York city, it is now more convinced that we need Geotech Earthquake Engineering



The world's tallest building is now seen in Taipei and PetronasTowers are no longer the world's tallest. Recently, the former Malaysian prime minister told the press that PetronasTowers are no longer the tallest single buildings,but as twin buildings they are still the tallest.

I am not bothered by who is the tallest as soon as they have a group of sound foundation. The contributions of geotechnical engineers should be highlighted for such a structure!?


  
 
Civil Engineering (=Soil + Wood/Timber)
Soil is one of the oldest construction materials that human have been working with. Civil Engineering was interpreted as soil and wood in the Chinese civilization, with the terminology adopted by many Asian countries. I visited the old Turkish city of Antalya in March 2002 in attending a NSF Workshop.  I was able to see structures that are made of stones (hard soils!). I was amazaed by the durability of these structures, which were constructed a few centuries before Christ yet they are still standing. The dry climate seems to have preserved them over so many centuries. In the east, such as Japan and China, some great temples and palaces were made of wood. That is, in the places where stones were not readily available, people searched for wood for construction (but they were frequently burnt down). This confirmed that early civilization started with soil and timber. [April 9, 2002]   Pictures of Perge and Aspendos

Meiji Shrine, Tokyo
 
The Most Acceptable Geotechnical Failure
How many people were amazed by the Leaning Tower of Pisa? Indeed more people were amazed by the geotechnical failures compared to the success we have achieved over the centuries. The Leaning Tower is one of the best examples to show that design without an adequate knowledge of soil mechanics would lead to failure. The Tower was constructed using shallow foundation. The pile foundation was likely not part of the practice at that time. 

Try the miditerm exam for Geotech Fundamentals where you calculate the factor of safety against bearing capacity failure and consolidation settlement or to have pile foundation instead of shallow foundation (under much idealized conditions).
 
Tilted Buildings
I haven't seen much tilted buildings until now. However, when I was small, there was a 3-storey tilted building - the tallest at that time but the tallest building is now about 30 stories? The building was constructed near the road and it sat on wooden pile foundations. The peat ground was very soft, so the road embankment was constantly upgraded to avoid flooding. However, filling generated lateral spreading in the ground and the soil moved toward the foundation of this tilted buidling. The soil started to heave and it eventually corrected the tilting of this building. This building is still standing upright after several decades of changes. 

I always thought that there are not many of this kind of tilted buildings over the world. However, my recent visit to Holland taught me very useful lesson. There are quite many old tilted buidlings in Amsterdam. Those buildings were perhaps constructed before we have soil mechanics. But I could sense that the soil foundation in Amsterdam is quite good because the brick retaining structures in the canals are standing upright and I did not notice any foundation failure for the walls.
 
Reinforced soils
Fiber-reinforced clay: Reinforced soil is a new technology? I saw oven that were made of clay when I was small. Inside the clay, there are jute fibers. Apparently in the old days, human have learned how to prevent cracking of the clay by mixing it with reinforcement. Unfortunately, such technology was never patented by my grandpa and his associates, so that humans are able to market such products in the modern age. It could be that people in the early days learned from some of the birds which make their nest using the reinforcements. 

Durability of reinforcement: Different types of polymeric reinforcements are available to strengthen the soil. I remembered seeing the trees being cut to prepare for the access road on the peat soil near my old house. The road embankment was then constructed and the new road became available. However, after several months, the road became uneven when the bending stiffness of these trees disminished. I now understand that it was because the trees (kind of soft wood) decomposed and the reinforcements disappeared. On the other hand, some houses constructed on the peat soil are still standing because they are supported by the roots of a different type of tree (hard wood). Thus, durability of reinforcement is extremely important for long-term performance of reinforced soil. 
 
Do we learn from experience?
Niigata earthquake taught us one of the first lessons about the danger of using shallow foundations for tall building constructed over liquefiable soil deposit. That was 1964 when the picture showed the titled buildings. The people told the press that they walked out of the roof. After several decades, we still saw many tilted buildings in a new city during one of the recent earthquakes. I asked why? The engineers replied that it was because of the political decision since the pile foundations are costing more. If that is the case, the engineers can't really help with mitigating the disaster. 
Photo linked from NISEE Repor
 
Contamination
Human have polluted the environment, such as air, water, and ground, as we settled down. A piece of land in the downtown area can be worthless because it is being contaminated by past manufacturing activities. A piece of farm land near your house can also be polluted by the pesticide. The sediments deposited in a river can also be polluted because of uncontrolled discharge of contaminats into the water environment. It is rather easy to pollute our environment, but the cost of bringing it back to a safe level is extremely high, time consuming and technically very difficult. Geoenvironmental Engineering is a discipline where we try to safeguard our environment, for example by designing a sound waste containment system, and to remediate any contaminated sites.

Failure:  If we do a post-failure investigation, we usually see more than a single mistake that led to the castastropic event. While structures can be redesigned and rebuilt, life can not. We live and die only once and we cannot afford to have any failures that may threaten our lives.

link to Geotech Program
non-technical issues