"A systematic experimental investigation has been made to ascertain the liquefaction (cyclic strength) behavior of loessial (silty) soils. No information on the mechanism governing the behavior of these soils under cyclic loads was previously available. This study is important in view of the seismicity of the mid-western region and loessial deposits in the area, especially those near the urban centers.
The test program for this purpose consisted of cyclic triaxial tests on both undisturbed and reconstituted samples. The soil samples used in this investigation were obtained from Shelby County, Memphis, Tennessee. The influence of parameters such as cyclic stress ratio, effective confining pressure, sample remoulding, natural water content, overconsolidation ratio and plasticity index on the liquefaction susceptibility of a loessial soil has been investigated. Strain controlled cyclic triaxial tests were also performed to determine the shear modulus and damping values for this soil. The influence of significant parameters, namely effective confining pressure and shear strain amplitude, on the modulus and damping values has been studied.
The test results indicate that the application of cyclic loads to saturated samples of loess results in a build up of pore water pressure equal to initial effective confining pressure. The samples also underwent failure defined in terms of 5, 10 or 20 percent double amplitude strain. Test samples at natural water content (degree of saturation < 100%) also suffered failure due to large cyclic strains. It was observed that the effect of increased plasticity reduced the build up of pore water pressures. A comparison was also made of the behavior of saturated loessial soil with that of a saturated sand and the difference in behavior of the two have been examined.
It was observed that the dynamic shear modulus for this loessial soil decreased with increasing shear strains increased with increase in effective confining pressure, and was sensitive to secondary time effects. The damping was found to be strain dependent, increasing with an increase in shear strain amplitude. Within the range of confining pressures used in the tests, no well marked effect of confinement on damping was noted"--Abstract, pages ii-iii.
Stephenson, Richard Wesley
Schmidt, Norbert O., 1925-2009
Senne, Joseph H.
Hansen, Peter G., 1927-2010
Civil, Architectural and Environmental Engineering
Ph. D. in Civil Engineering
University of Missouri--Rolla
xxii, 295 pages
© 1984 Vijay K. Puri, All rights reserved.
Dissertation - Restricted Access
Loam soils -- Plastic properties
Shear strength of soils
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Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.http://merlin.lib.umsystem.edu/record=b1633365~S5
Puri, Vijay Kumar, "Liquefaction behavior and dynamic properties of loessial (silty) soils" (1984). Doctoral Dissertations. 545.
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