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Centrifuge |
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 automated triaxial system of the 90's (U of Tokyo system) |
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 triaxial system developed by Burmister in 1930-40's
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Why is this branch of knowledge known as geotechnical
engineering? I felt more like to use the term geoengineering.....
(8/29/2006)
Soil Mechanics/Geomechanics is sometimes confused as Geology or Soil Science [but there are similarities with geological engineering]. In soil mechanics, we study and characterize the properties of soils that are relevant for engineering analysis or design. We study the behavior of soil, up to failure, due to external or internal loading. Different natural or man-made soil structural systems, ranging from very traditional to recently developed ones, are studied. I have a bit of writing about geotech to share with you.
The geotechnical research at Columbia University is directed toward laboratory testing, theoretical analysis, and verification of theories and experimental works. The Burmister Geotechnical Laboratory, a state-of-the-art research and teaching laboratory for soils, is located in Room 706, MUDD Building.
We have installed a state-of-the-art 200g geotechnical centrifuge, which enhanced greatly our experimental research capability.
The Burmister Lecture and DJ Memorial Lecture are our annual events. Biot Lecture is also closely related to geomechanics.
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The state-of-the-art laboratory apparatuses are designed and fabricated
with direct input from Hoe Ling and his
research collaborators
. The laboratory is housed with an automated
Plane Strain device
and and also a
triaxial device
, both of which allow stress path testing of soils at both drained and undrained
conditions (
basic concept of automation
). A large
direct shear device
is also available for studying shear strength of soils and interaction properties
between soils and geosynthetic materials. The triaxial and direct shear devices
accommodate specimen of several different sizes. Currently, an integrated
system is being developed for the instrumentation and control of these devices.
(Visit the parent or
sister apparatuses
at the University of Tokyo)
Model Test: A sand box is available to conduct model tests. This box allows pressure or suction to be applied to the soil foundation under saturated conditions. A displacement-controlled jack is attached to this sand box. A unique sand hopper is available to prepare the foundation and slope for small-scale model testing. The hopper creates automatically uniform sand foundation under very precisely controlled conditions, such as the falling height and opening size. This sand hopper is also used to prepare uniform foundation of different densities for liquefaction testing in the centrifuge.
Take a look at some of unique equipments again. Click here
Large-scale tests are conducted for geotechnical earthquake engineering
related to the performance of pipeline under liquefied soils and of slope
stability.
Soil Constitutive Modeling: Research has been conducted to develop a simplified anisotropic bounding surface model based on the critical state concept. The model was extended to consider viscoplastic behavior of clay. The model has bene validated with test results for different clays, normally consolidated and overconsolidated, and different modes of shearing. The ultimate goal is to develop a procedure capable of simulating the behavior of soil deposit subject to long-term loading.
A sand model was also developed by modifying the generalized plasticity model to include pressure-level effects and cyclic hardening behavior. The model is being used for the numerical analysis of soil structures.
Debris Flow: We started to get into this area with a great interest in the debris flow hazards in Taiwan. The study will be on the mechanics and simulation of debris flow, and hazard mapping.Permanent Displacement of Geosynthetic-Reinforced Soil Retaining Walls: The reinforced soil retaining wall system has been studied through experimental and analytical methods. The cyclic behavior of geogrids has also been studied. A cyclic model for geosynthetic, based on bounding surface elasto-plasticity has been formulated and implemented for numerical analysis.
A preliminary study on the seismic performance of GRS-RW under a joint collaboration with the Tokyo Institute of Technology, using the centrifuge shaking table tests, was initiated two years ago. A finite element proceudre is verified with the test results.
Information on above two projects are available at the centrifuge page .
We also made separate trips to Taiwan and Turkey to investigate the performance of reinforced soil structures during 1999 Ji-Ji and Izmit earthquakes. Several reinforced soil structures failed during the earthquakes. A project funded by the National Science Foundation is in progress to validate our design methodologoes with reference to the structures that failed. Meanwhile, an International Workshop was held for advancing the knowledge on this issue at Columbia University on Oct 30 & 31, 2000. Some information are available on this page
Deformation of Modular Block Geosynthetic-Reinforced Soil Retaining Walls: A numerical study related to the performance of geosynthetic-reinforced soil retaining walls, with modular block facing, has been completed. The finite-element procedure employing M-CANDE was verified with the field performance of a full-scale geosynthetic-reinforced soil retaining wall constructed at the Public Works Research Institute, Ministry of Construction, Japan. A series of parametric studies were also conducted to investigate the various properties of geosynthetic reinforcement, foundation and backfill soils, block interaction, etc., on the overall performance.
Performance of Pavement Reinforced with Geosynthetic: Geosynthetic materials are used in the flexible pavement system. Static and dynamic tests were conducted to investigate the performance of pavement-geosynthetic system. The finite-element procedure is used to simulate the test results. Upon successful modeling of the soil-pavement system, a series of parametric studies were conducted.
Waste Containment System: We also conduct studies on the geoenvironmental engineering issues: settlement of municipal solid waste landfill, seismic stability and permanent displacement of landfill cover system, soil-geomembrane interaction, sand capping of contaminated submarine sediments.A series of shaking table tests related to the stability of landfill cover soil have been conducted at Dalian University of Technology. We modified the direct shear box for studying the interaction properties between cohesive soils and geomembrane. A tilting table test was manufactured for studying the interaction properties at very low confining pressure.
International Collaboration: We are promoting actively
international research collaboration. Over the past several years,
Geotechnical Laboratory has collaborated closely with the Japanese
industries, universities as well
as the governmental research institutes from different ministries, and
also
with a few other countries. International students from Japan, Italy,
Spain, among other countries, have joined us in the graduation research
projects.
Past research may be found in the list of
publications
.
