Abstract
Modelling the horizontal displacements in subsoil is essential in many geotechnical design situations. Especially dilatation angle should be correctly defined in order to ensure accurate modelling. Hence, this paper studies how the direction of stress path affects the dilatation angle of various soils. The study utilizes numerous anisotropically consolidated and drained compression triaxial tests, and the samples represent normally consolidated soft clay, stiff over-consolidated silt and dry sand. The plastic potential function is derived based on the triaxial test results, using stress values in which the dilatation angle is identical to the direction of stress path. The shape of potential function is assumed to be similar to the yield function, but with different parameters (non-associated modelling of strains). Finally, deformations are calculated by using the concept of potential energy, which is a second order function in mean effective stress - deviatoric stress-space. Simulated values are then compared to triaxial test measurements, and the agreement between values is found to be rather good.
Highlights
Modelling the horizontal displacements in subsoil is essential in geotechnical design situations such as sheet pile walls and embankments with low stability
The plastic potential function is derived based on the triaxial test results, using stress values in which the dilatation angle is identical to the direction of stress path
Triaxial tests on Ojakkala sand have shown that samples compacted to identical density and in same initial pressure exhibit different dilatation when the direction of stress path is varied
Summary
Modelling the horizontal displacements in subsoil is essential in geotechnical design situations such as sheet pile walls and embankments with low stability. The potential function is derived based on triaxial test results, using stress values in which the dilatation angle is identical to the direction of the stress path. These data points are the points where the dilatation angle δεv/δεs is identical to the slope of the stress path ∆p/∆q In these points the normal of potential function g has the same slope in (p,q)-space. That g is determined, we know the two vectors that affect the dilatation angle δεv/δεs These are the applied incremental stress-vector (∆q,∆p) and the normal of potential function g. In figure 2d, the observed and calculated dilatation angles δεv/δεs are shown as a function of stress ratio q/p with various directions of stress paths. Where k is a parameter, which depends on the slope of the stress path
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