An extensive literature review and experimental study were performed to investigate whether cavitation and dissolved gases exiting solution from soil pore water are the cause of the erratic undrained behavior often observed in triaxial tests on saturated, dilatant silts.
The literature indicates that ground water contains various amounts of dissolved gases and that gases dissolved in soil pore water will have sufficient time to exit solution to some extent, due to the pore pressure reductions which occur during sampling and unconsolidated-undrained triaxial tests. The exit of dissolved gases from solution would increase the soil volume and affect its undrained behavior.
Experiments were performed on saturated silts to measure the pore pressure reductions which occur during sampling and unconsolidated-undrained triaxial tests. The amount of dissolved air that could come out of solution and the desaturation that a saturated soil sample could experience were also estimated.
Gas bubble formation and growth within the pores of a saturated silt could affect intergranular forces and influence the stress-strain behavior of the soil in undrained tests. Variations in the amount of dissolved gas exiting solution and forming bubbles from one specimen to another could be the cause of the erratic undrained behavior often observed for saturated silts. Bubble growth within the soil pores is believed to have lead to abrupt strain-softening in a number of the undrained tests performed in this research.
Variations in specimen disturbance may also contribute to the erratic behavior observed in undrained tests on silts. Disturbance levels and their influence on soil behavior are difficult to quantify.
Due to the unusual properties of water under negative pressure, the initial value of pore water pressure within the soil appears to have a direct influence on the undrained strength of the soil. As a result, laboratory pore water pressures should be similar to in-situ pore water pressures, in order to give reasonable undrained strength measurements. The findings of this research are believed to be worthy of further study. / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/30066 |
| Date | 12 December 2008 |
| Creators | Rose, Andrew Thomas |
| Contributors | Civil Engineering, Brandon, T.L., Duncan, J. Michael, Martin, James R., Filz, George M., Kriz, Ronald D. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | 2 volumes (xxxix, 812 leaves), BTD, application/pdf, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 32807090, LD5655.V856_1994.R673.V.1.pdf, LD5655.V856_1994.R673.V.2.pdf |
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