| Author | Mukherjee, Kaushik |
| Call Number | AIT Thesis no. GT-89-03 |
| Subject(s) | Vertical drains
|
| 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-89-03 |
| Abstract | Among the various available ground improvement techniques today,
the use of prefabricated vertical drains is a popular one. Vertical drains
are used to accelerate the consolidation by taking the advantage of higher
rate of horizontal flow of water through the soil. Generally, in this type
of ground improvement technique, after the installation of vertical
drains, the soft subsoils are preloaded to achieve faster consolidation .
The present study is aimed at the prediction of the performances shown
by the Alidrain (Canada), in the field under embankment loading and in
the laboratory in large scale consolidometer by using a finite element
model of the transient, axisymmetric flow problem considering equal
strain. This model also considers the disturbances caused by the driven
mandrel to the surrounding subsoil (smear effect). The data collected from
the field and the laboratory has been compared with the results from this
model. The model demonstrated good prediction of both the field and
laboratory performances with proper choice of the Cfield/Clab ratio, the
smear zone diameter (ds) and the kh/kh' ratio for the smear zone . The soil
parameters, which were used as the input data for this model, were
calculated from different laboratory experiments like Rowe Cell,
Oedometer and CIU Triaxial Tests. For the prediction of consolidation
settlement in the field, a kh/kh' ratio of 10 with the combination of
d /d equal to 2 has been shown to give the best prediction . For the best
s m
prediction of the pore pressure in the field, slightly higher value of
Cvfield/Cvlab has been found particularly at a deeper depth. The presence
of silt and sand seams, location of the piezometers and high smear effect
can be the reason. On the other hand, using reconstituted sample in the
laboratory, the results showed better conformity with degree of
consolidation with kh/kh' equal to 2 and ds=2dm. For the calculation of
initial induced stresses by the embankment loading, two different methods
were followed - one is by using Gray's Equations and other by using the
ISBILD program. Generally, use of Gray's Equations gave rise to a higher
value of initial excess pore pressure than by using ISBILD. However, the
main program being the same, use of both Gray's Equation and ISBILD showed
same trend of results. |
| Year | 1990 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GT-89-03 |
| 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) | Bergado, Dennes T. Honjo, Yusuke; |
| Examination Committee(s) | Indraratna, Buddhima; |
| Scholarship Donor(s) | The Government of Italy.; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1990 |