Effect of confining pressure, relative density and shear strain on the Poisson's ratio of clean sand

Troyee Dutta, Sireesh Saride

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther

Abstract

In comparison to other dynamic properties of soil, Poisson’s ratio is mostly considered as an elastic constant. The effect of different parameters on the Poisson’s ratio of soil is neglected in most of the available literature. Proper estimation of the Poisson’s ratio is required as it signifies the stress and
deformation characteristics of the soil. In this study a series of resonant column tests were performed to determine the variation of Poisson’s ratio with confining pressure, relative density and shear strain.

Clean sand free from fines content was used in this study. The tests were performed on sand sample of size 50 x 100 mm compacted at relative densities of 30%, 50% and 75%. The sample preparation was done by using a split mold. By using a funnel, the sand was gently poured into the split mold. Then each
layer was compacted by means of a tamping rod which weighs 150 g. The sample preparation was done in 5 equal thick layers. By performing few trial sample preparations, the number of blows required per layer for a desired relative density was determined. A fixed free type of resonant column was used in this study. By performing the resonant column test in torsional mode as well as flexural mode of excitation, it is possible to estimate the Poisson’s ratio of the soil. The confining pressure was varied from 100 kPa to 800 kPa. The shear strain varied from 10-4 % to 10-1 %.

Figure 1 gives the variation of Poisson’s ratio with confining pressure for various relative densities. From the figure it is observed that there is a continuous decrease in Poisson’s ratio of the soil with an increase in the confining pressure as well as relative density. The percentage reduction in Poisson’s ratio obtained
for the soil subjected to a confining pressure of 800 kPa as compared to soil subjected to 100 kPa confining pressure is 19 %, 21 % and 22% for 30 %, 50 %, 75 % relative densities of the soil. In addition, the percentages reduction in Poisson’s ratio of sand prepared at 75 % relative density as compare to 30 %
relative density are 14 %, 15.7 %, 16.7 % and 17.6 % for sand subjected to 100 kPa, 400 kPa, 600 kPa and 800 kPa respectively. It can be concluded that the percentage reduction in Poisson’s ratio increases with the increase in confining pressure as well as relative density.
Original languageEnglish
Title of host publicationProceedings of the 50th Indian Geotechnical Conference
Number of pages8
Publication statusPublished - 2015
Externally publishedYes
EventIndian Geotechnical Conference 2015 - Maharashtra, India
Duration: 17 Dec 201519 Dec 2015
Conference number: 50th

Conference

ConferenceIndian Geotechnical Conference 2015
Abbreviated titleIGC 2015
CountryIndia
CityMaharashtra
Period17/12/1519/12/15

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