Date of Award

Spring 2011

Project Type


Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

Pedro de Alba


Natural and constructed slopes may contain zones of loose granular soils capable of liquefaction. Liquefied soils behave like heavy fluids and consequent rapid flowslides can produce great damage. The "residual strength" (Sur) of the liquefied soil can be estimated by back-calculation from field case histories; however, very little confirmation laboratory testing has been conducted thus far. A reliable laboratory measurement technique is needed to independently verify Sur values used for mitigation design.

A ring shear device (RSD) designed and built at the University of New Hampshire (UNH) allows for residual strength testing under controlled strain rates and infinite total strain. The Sur of a fine sand, "Ottawa F-75," was analyzed using the RSD. These results were verified by comparison to residual strength values obtained by geotechnical centrifuge testing. This study indicates that the UNH RSD can be a reliable tool for estimating the residual strength of liquefied soil.