Modeling the relation between suction, effective stress and shear strength in partially saturated granular media

Decades of geotechnical research firmly established that the mechanical properties (shear strength and deformation characteristics) of soils are related to soil's "effective stress", i.e. the stress carried by the solid matrix. The remaining stress is carried by the pore fluid in the form of pore pressure. In unsaturated soils, the coexistence of water and air results in negative pore pressure, which are termed "soil suction". A clear link between soil suction and effective stress has not yet been established. This research develops a model for linking effective stress to total stress and soil suction for uniform, spherical particles, at low water contents. The model includes the analytical formulation of water geometry and forces at the micro-scale. The change in effective stress due to soil suction is estimated from this particle contact scale, taking account of the particle packing. A method for inferring the effective stress in an unsaturated soil from strength test results is also proposed. In order to examine the partially saturated mechanical behavior of granular materials, a triaxial test setup was modified to accommodate an MIT Tensiometer as its pedestal. Materials consisting of uniform spherical glass beads were tested, under both saturated and unsaturated conditions, at conditions that matched those of the model.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Toker, Nabi Kartal, 1979-

Advisor dc:contributor.advisor

• John T. Germaine and Patricia J. Culligan.

• Civil and Environmental Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/39354
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/39354

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/39354