June 14, 2009
June 14, 2009
June 17, 2009
14.173.1 - 14.173.8
AN INEXPENSIVE CYCLIC TRIAXIAL SYSTEM FOR EDUCATIONAL UNIVERSITIES Abstract
Liquefaction is the term commonly used to describe the sudden, dramatic strength loss that sometimes occurs in soils during seismic loading. While most frequently associated with cohesionless soils such as sands and silts and the dynamic loadings due to earthquakes, it has been reported in many types of soils under both dynamic and static loadings. As the built environment grows, its susceptibility to seismic damage is increased proportionally, thus the need for training engineers in seismic behavior and design, and the need for research in these areas, also increase. Unfortunately, due to the high cost of dynamic soil testing equipment, few students are able to have hands-on experience with this type of soil testing. Dynamic soil testing equipment such as cyclic triaxial and cyclic simple shear machines typically ranges from $60,000 to $200,000. As a result, typically only students at large research universities have any exposure to this type of testing and only those performing research have anything more than an observational experience.
The apparatus discussed in this paper reflects the author’s attempt to develop an affordable dynamic soil testing system (less than $10,000). Such a system will make the study of dynamic soil behavior available to students at small universities and at universities in developing countries who cannot afford to purchase such equipment. The paper outlines the design and construction of a cyclic triaxial machine that can be constructed by universities that lack the large research budgets to purchase such equipment. Such a device will allow students at smaller universities the opportunity to study the dynamic behavior of soils first-hand and to develop viable undergraduate research programs in this area.
In addition to the information on the system provided in the paper, the author will freely provide, through a website, schematics of the system, software for controlling and monitoring the system (written using the computer software Labview), and guidance in setting up and operating the system.
Earthquakes pose one of the greatest natural threats known to the human race. They pose a threat to citizens of almost every country on the planet. Within the last few years, earthquakes have claimed tens of thousands of lives in China, Pakistan, and Central America alone. The December 26th, 2004 tsunami, triggered by a magnitude 9+ earthquake off the Sumatran coast, claimed over 225,000 lives in eleven countries. Even developed countries are not safe from the impacts of earthquakes. The January 17th, 1994 Northridge earthquake killed 72, injured more than 9000, and caused an estimated $44 billion in damages. Exactly one year later, the Kobe Earthquake in Japan killed at least 5100 and caused over $200 billion in damages.
The world’s infrastructure is at constant risk from earthquakes. Structures that are founded on or built out of soils are particularly vulnerable due to the nature of the material. The behavior of soils during seismic events is largely controlled by the behavior of the water pressures within
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