An Approach to 1g Modelling in Geotechnical Engineering with Soiltron

Complex problems in geotechnical engineering and soil mechanics can be
investigated with physical modelling, where the structures in a
geometrically n-times smaller scale are reproduced and the occuring
forces and deformations are measured. Problematic is the reduction of
pressures and the subsequent change of the mechanical behaviour of
the model soil. The versatility of field and model test is shown by
examples from the literature.

In this thesis the similarity between barotropy and pyknotropy was used to
model prototype soil behaviour. Soiltron is a prototype soil, which is
treated with light and soft additives to achieve the same relative
density in the model at an n-times smaller pressure as in the prototype. The
stiffness and strength of the new material can be influenced to simulate
prototype material behaviour by the control of the soil density. Thus, the
use of that soil as material in small scale 1g~models is possible.

At the Institute of Geotechnical and Tunnel Engineering of the University of
Innsbruck a model soil material was not available in sufficient quantity.
Therefore, a large quantity of quartz sand was purchased and its mechanical
behaviour was investigated in detail with triaxial test devices using local
strain gauges. The specimen deformations were inspected with evaluation of
remote measurements using PIV. Systematic and random test errors have been
avoided or have been taken into account.

Appropriate regressions have been found to relate pressure and density to
the properties of the soil and to calculate the required density of
Soiltron. The appropriateness of Soiltron is verified in two demonstration
model tests.

This work can be seen as foot step to strike a new path in physical
modelling.