Title
Numerical application of SPH method for deformation, failure
and flow problems of geomaterials( 内容の要旨(Summary) )
Author(s)
野々山, 栄人
Report No.(Doctoral
Degree)
博士(工学) 甲第397号
Issue Date
2011-03-25
Type
博士論文
Version
none
URL
http://hdl.handle.net/20.500.12099/36580
※この資料の著作権は、各資料の著者・学協会・出版社等に帰属します。
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Numerical application of SPH method for deformation, failure and flow
problems of geomaterial8
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By predicting all deformation process of geomaterial ltom initialstate to large deformation, including
failure and flow, variant useful information can be given for the design of structures and for the disaster prevention. However, in traditional method, the imitialsmall deformation and the large deformation are solved
separately using different simulation tools. If the all deformation process can be solved using one method, it is
not necessary to change the method for each
problem. Also, it is possible to apply the method to various
problems flexibly and to figureout mechanisms of phenomena easily.
SPH (Smoothed Particle Hydrodynamics) method which isone of the mesh-free Lagrangian scheme based
on
continuum approximation has a possibility for solving the all deformation process
of geomateria1. In this
thesis, a potential of SPH method is discussed. The method is adapted to the all deformation process of
geomaterial from initialstate to large deformation, failure and now. SPH method can be utilized both the solid
mechanics and the fluid dynamics. Therefore, two approaches, the solid mechanics approach and the fluid dynamics approach, are discussed in this thesis. The contents of this thesisare summarized as follows:
Chapter 1 contains the general introduction of thisthesis.The background and
objectives
are explained.In Chapter 2, some numerical methods that have proposed for the large deformation
analysis are
summarized. These methods are classifled into some groups, and features of each group are discussed. In
addition, developments and problems of SPH method based on solid mechanics and fluid dynamics are
summarized separately. Furthermore, some numerical results of geoteclmical engineering reported in the
previous studies are introduced.
In Chapter 3,basic theory of SPH method is described in detail.The formulations of SPH method based on
both solid mechanics and fluid dynamics are explained. The
&amework
of the two phase mixture theory is alsoexplained. Moreover, 1)the validation of the smoothing function and 2) the nearest
neighboring
particlesearching scheme and 3)thetreatment technique of the boundary conditions are written in this chapter.
Chapter 4 shows some validations of the numerical methods developed inthis thesis. The obtained results
are compared with the theoretical solution, the existing experimental and simulated
results. The method based
on the solid mechanics was adapted to the simple shear test and the plane strain compression test. Itwas shown
that it is possible to calculate suitablestress state of the geomaterial with a
high
degree ofaccuracy. In addition,the Jaumann stress rate was successfully introduced in the calculation process. The
method based on fluid
dynamics was adapted tothe dam-break problems ofNedonian hid. According to the results, itwas found that
the method can express the deformation behavior and the surface conflguration of Newtonian hid. The static
earth pressure of saturated elasticporous media was simulated using the two phase mixture theory. Itwas found
that the method can describe the effective stress and the pore water pressure. The
simulations of the gravitational now were also conducted using the method based on fluid dynamics. The developed
Bingham
fluid model is introduced to express now behavior of geomaterials. It was confirmed that the different
deformation behavior can be reproduced by the changing the material parameters.
Chapter 5 shows some simulated results of geotechnical problems. The slope
stabilityanalyses and the excavation analyses were camied out. Itwas found that the method can describe deformation behavior even
during large deformation and excavation. Itwas also confirmed the effect of countermeasure can be estimated in
SPH simulation. In the simulation of falling head permeability tests,the method based on the two phase mixture
-9-theory is used. From the results,it was confirmed the interaction between geomaterial wd water can be
described accurately in dynamic now condition. The method based on nuid dynamics is adopted to simulate a
penetration of rigid body into ground. Suitable deformation behavior of ground could be reproduced in the simulations. The method was also adapted to the simulation of now of geomateria1. It was shown that itis
possible to express the deformation behavior of the now of geomaterials and to estimate effect of the protecting
walls.
Finally, conclusions and remarks on future works are mentioned in Chapter 6. There are stillshortages of
the method derived &om the fundamental problems. However, applicabilityof the methods for prediction of all
deformation process ofgeomaterial could be shown inthis thesis.
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