Strength Analysis in Geomechanics|岩土工程数值方法与理论 - 领先的岩土技术社区，岩土领域的媒体、社区与应用平台！

离线hetang

高级工程师

发帖: 127

土币: 172

威望: 1125

原创币: 0

只看楼主倒序阅读使用道具楼主发表于: 2009-08-11

Strength Analysis in Geomechanics

by
S. Elsoufiev

Springer, 2007

Foundations of Engineering Mechanics
Series Editors: V.I. Babitsky, J. Wittenburg

It is hardly possible to find a single rheological law for all the soils. However,
they have mechanical properties (elasticity, plasticity, creep, damage, etc.)
that are met in some special sciences, and basic equations of these disciplines
can be applied to earth structures. This way is taken in this book. It represents
the results that can be used as a base for computations in many fields of the
Geomechanics in its wide sense. Deformation and fracture of many objects
include a row of important effects that must be taken into account. Some of
them can be considered in the rheological law that, however, must be simple
enough to solve the problems for real objects.
On the base of experiments and some theoretical investigations the constitutive
equations that take into account large strains, a non-linear unsteady
creep, an influence of a stress state type, an initial anisotropy and a damage
are introduced. The test results show that they can be used first of all to
finding ultimate state of structures – for a wide variety of monotonous loadings
when equivalent strain does not diminish, and include some interrupted,
step-wise and even cycling changes of stresses. When the influence of time
is negligible the basic expressions become the constitutive equations of the
plasticity theory generalized here. At limit values of the exponent of a hardening
law the last ones give the Hooke’s and the Prandtl’s diagrams. Together
with the basic relations of continuum mechanics they are used to describe the
deformation of many objects. Any of its stage can be taken as maximum
allowable one but it is more convenient to predict a failure according to the
criterion of infinite strains rate at the beginning of unstable deformation. The
method reveals the influence of the form and dimensions of the structure on
its ultimate state that are not considered by classical approaches.
Certainly it is hardly possible to solve any real problem without some
assumptions of geometrical type. Here the tasks are distinguished as antiplane
(longitudinal shear), plane and axisymmetric problems. This allows
to consider a fracture of many real structures. The results are represented
by relations that can be applied directly and a computer is used (if necessary)
on a final stage of calculations. The method can be realized not only in
Geomechanics but also in other branches of industry and science. The whole
approach takes into account five types of non-linearity (three physical and
two geometrical) and contains some new ideas, for example, the consideration
of the fracture as a process, the difference between the body and the element
of a material which only deforms and fails because it is in a structure, the
simplicity of some non-linear computations against linear ones (ideal plasticity
versus the Hooke’s law, unsteady creep instead of a steady one, etc.), the
independence of maximum critical strain for brittle materials on the types of
structure and stress state, an advantage of deformation theories before flow
ones and others.
All this does not deny the classical methods that are also used in the book
which is addressed to students, scientists and engineers who are busy with
strength problems.

附件: