HR: 1340h
AN: H33B-0463    [Abstracts]
TI: Hydraulic Properties of Deformable Structured Soils
AU: * Carminati, A
EM: andrea.carminati@env.ethz.ch
AF: Inst Terrestrial Ecology ETHZ, Grabenstrasse 11a, Schlieren, 8952 Switzerland
AU: Kaestner, A
EM: anders.kaestner@env.ethz.ch
AF: Inst Terrestrial Ecology ETHZ, Grabenstrasse 11a, Schlieren, 8952 Switzerland
AU: Koliji, A
EM: azad.koliji@epfl.ch
AF: Soil Mechanics Laboratory LMS-EPFL, ENAC-ICARE, Lausanne, 1015 Switzerland
AU: Vulliet, L
EM: Laurent.Vulliet@epfl.ch
AF: Soil Mechanics Laboratory LMS-EPFL, ENAC-ICARE, Lausanne, 1015 Switzerland
AU: Hassanein, R
EM: rene.hassanein@psi.ch
AF: PSI, Paul Scherrer Institut, Villigen, 5232 Switzerland
AU: Vontobel, P
EM: Peter.Vontobel@psi.ch
AF: PSI, Paul Scherrer Institut, Villigen, 5232 Switzerland
AU: Ippisch, O
EM: olaf.ippisch@iwr.uni-heidelberg.de
AF: IWR-UNI-Heidelberg, Neuenheimer Feld 348, Heidelberg, D-69120 Germany
AU: Fluhler, H
EM: fluehler@env.ethz.ch
AF: Inst Terrestrial Ecology ETHZ, Grabenstrasse 11a, Schlieren, 8952 Switzerland
AB: We examine the hydraulic and mechanical behavior of structures such as aggregates separated by interaggregate pores. Structured soil is susceptible to deformation under hydraulic and mechanical loading, leading to soil compaction. To describe water flow in structured soils, dual-permeability models consider the soil as two separate but interacting porous domains: a macro-pore system and a less permeable matrix pore system. Most of the existing models assume rigidity of the soil. On the other side most of the models describing deformable soils assume that the soils are homogeneous and their hydraulic properties time invariant (i.e. no change during compaction). The goals of our research is (i) to test whether Richards equation properly describes the flow in the micro-porous system of aggregates; (ii) to identify their hydraulic properties and (iii) to predict the change of the material functions in the course of compaction of the aggregated medium. We use neutron radiography and tomography to quantify the water exchange between aggregates. The aggregates were assembled in 2 mm thick slab forming quasi a 2-dimensional bedding. The larger aggregates were wetted with water and were embedded in smaller aggregates wetted a lower water content with heavy water. The water/heavy water exchange was imaged and simulated by solving the Richard's equation. The trend of the experimental and the simulated water exchange (both proportional to the square root of time) was a first test of the validity of Richard's equation in an aggregated soil. By matching the observed flow field and solving an inverse problem, the hydraulic properties of the sample (i.e. the properties of the individual aggregates) will be identified. A second goal was to find effective constitutive relations for the aggregated medium. This experimental system will be tested by dynamic tomography in a triaxial-load-cell.
DE: 5104 Fracture and flow
DE: 5139 Transport properties
DE: 3210 Modeling
DE: 3260 Inverse theory
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting