| Author | Pokharel, Gyaneswor |
| Call Number | AIT Thesis no.GT-90-18 |
| Subject(s) | Water, Underground--Analysis
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of
Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GT-90-18 |
| Abstract | In this research, a parametric infinite element is presented which
approximates the far field behavior based on the analytical solutions so that
the effective a rea of study (i.e. the near field) can be r educed. This is particularly
necessary when the size of influence ls much larger compared to that of the
zone of interest. Furthermore, it is almost always the case that the geotechnical
data outside the concerned area (e.g. a construction site) is limited , and it is
expediently assumed that there is the constant head boundary at infinite distance.
In this study, homogeneous and isotropic confined aquifer is considered by
modelling the near field using the conventional finite elements and the far field
using the infinite elements. Initially far field behavior of flow through porous
media is studied by the analytical solution for three basic types of flow: 3-D
full s pace flow under point source, axi-symmetric 2-D radial flow, unidirectional
(1 - D plane ) flow in an infinite plane induced by a pumping trench at the
center. Consequently, the coordinate transformation functions are derived for
the infinite element based on "Finite Element by Singular Contraction" concept
(according to Rajapakse and Karasudhl 's (1985) definition). The developed
transformation functions have been applied and calculated solutions are compared
to Theis solution for the axi-symmetric flow and the analytical solution for 1-D
plane flow, respectively. The calculation shows that the result with the finite
elements in near field and the infinite elements in far fields gave better results
compared to the finite elements alone with the fixed head boundary at intermediate
distance.
Finally, the methodology developed is applied to a pumping test result whose
purpose was to evaluate the performance of a newly developed continuous sheet
cut off wall. Good results are obtained by using infinite elements in far field
along with considerably small sized near field discretized by the finite elements.
In spite of the very complex configurations of the sheet piles and other structures,
the calculated results using the infinite elements coincide to the observed
drawdown surprisingly well.
It should be emphasized that, the main feature of the present infinite
element scheme is that it can employ the same integration scheme (i.e.
Gauss-quadrature) for integration of both finite and infinite elements in processing
the stiffness matrices.
Finally, the implementation of these elements is very straightforward, and
they are ideally suited for the analysis of the infinite domain and the construction
sites where the area of interest ls very small compared to the area of influence. |
| Year | 1991 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GT-90-18 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Geotechnical and Transportation Engineering (GT) |
| Chairperson(s) | Honjo, Yusuke |
| Examination Committee(s) | Balasubramaniam, A.S. ;Bergado, Dennes T. ;Indraratna, Buddhima
|
| Scholarship Donor(s) | The Government of Australia ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1991 |