| Author | Pinit Phamvan |
| Call Number | AIT Diss. no. GT-89-01 |
| Subject(s) | Piling (Civil engineering)--Testing
|
| Note | A dissertation submitted in partial fulfillment of the
requirements for the degree of Doctor of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. GT-89-01 |
| Abstract | A comprehensive instrumented pile testing program was carried out to evaluate
the behavior of driven piles in Bangkok subsoils. The field experiments were
designed to provide long- t erm data on negative skin friction development due to
excessive settlements of the surrounding soils. The pile behaviors was
investigated from the installation process, up to the stage of long- t erm negative
skin friction under an embankment surcharge load. Prior to the embankment
surcharge, the piles were subjected to short - term pull-out tests. Thus the
short-term and long-term s kin friction can be studied.
Two instrumented hollow prestressed precast concrete piles (0.4 m diameter
and 26 m in length) were driven to bear in the stiff clay l aye r. They were
divided into six segments and tested in tension for different pile lengths. The
distribution of axial forces along the piles was recorded by two independent
systems, load cells and tell- tale rods. Pore pressures and ground movements were
monitored heavily in the vicinity of the test piles. In-situ strengths and the
initial stress state of the test site were determined before the pile was driven.
Subsoil properties were evaluated through an extensive laboratory testing
program. After the short- t erm pull-out tests, an embankment of the size 24 x 14
m2 and 2 m height was constructed over the test site to provide a uniform
surcharge load, which would accelerate the settlements of the surrounding ground.
The long- t erm behavior was monitored for a period of about 9 months. The
effectiveness of slip coat material was also studied by coating one of the test
piles with bitumen compound slip layer.
Negative skin friction load on pi l es was found to be dependent on t he
settlement of the surrounding soil. The results of short-term load tests are
able to estimate the behavior under long- term conditions. The effective stress
approach, with a~ value of 0.25, may be used as an upper bound for the
prediction of negative skin friction. The bitumen coated material was proved to
reduce the negative skin friction to one third of the negative skin friction on
the uncoated pile.
The load- deformation behavior of the piles due to negative skin friction
load was modelled by a FE scheme. An interface element was developed, using the
stress-strain characteristics obtained from consolidated-drained direct shear
tests, to simulate the behavior at the pile- soil interface. The analysis
predicted satisfactorily the actual behavior of the piles under long- term
conditions, using the parameters derived from short term pull-out tests. |
| Year | 1989 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. GT-89-01 |
| Type | Dissertation |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Balasubramaniam, A.S.;Indraratna, B.; |
| Examination Committee(s) | Bergado, Dennes T.;Worsak Kanok-Nukulchai;Noppadol Phien-wej; |
| Scholarship Donor(s) | The Government of Japan; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1989 |