Contact analysis has been one of the most difficult
problems in applied mechanics, where theoretical
solutions can only be obtained for limited and simple
cases of boundary conditions because of their
non-linearity. Since computational mechanics has
been sufficiently developed for contact analysis,
contact problems encountered in the biological sphere
can now be solved numerically without difficulty once
a proper model is constructed by physics. From the
viewpoint of the soil environment, Faure applied the
finite element method (FEM) to analyze the pressures
exerted by root growth in soils based on the idea of
cone penetration, where the deformation of the root
was not considered (Faure, 1994). Plant proposed a
mathematical model of root growth in terms of water
flux from surrounding soil (Plant, 1983).