| Author | Buensuceso, Benjamin Ramos, Jr. |
| Call Number | AIT Diss. no. GT-89-02 |
| Subject(s) | Clay--Thailand--Bangkok
|
| 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-89-02 |
| Abstract | The strength and deformation characteristics of lime treated soft cl ay were
studied through a comprehensive series of unconfined, oedometer and triaxial
tests, in which the effects of lime content and curing time were considered.
The base cl ay used were samples of lightly over consolidated soft Bangkok clay,
with an organic content of 4.3%. Quicklime powder was used to stabilize the soft
clay, and lime contents were varied from 2.5 to 15%. For the unconfined
compression and oedometer tests, the soil properties were monitored for a period
of 6 months , while the triaxial tests were conducted at one and two months curing
time. The range of pre-shear consolidation pressures employed in the triaxial
compression tests were from 5 to 60 t/m2 •
The unconfined compressive strength of lime treated clays was found to
increase with curing time, and that a lime content of 10% can be regarded as an
optimum lime content to result in the highest relative strength gain. Results
of the oedometer tests revealed that lime treatment also resulted in improved
consolidation properties, considering the apparent increase in vm, the lower Cc
and the higher cv after lime treatment.
Based on the triaxial stress-strain characteristics, stress paths, pore
pressure development and volume change characteristics , it was established that
the main effect of lime treatment was to change the strength and deformation
characteristics of the soft clay from normally consolidated to over consolidated
cl ay behavior. The degree of over consolidation was influenced by the lime
content, curing time, jo, and the applied stress path. Heavily over consolidated
(rigid) behavior was observed for stress states inside the volumetric yield locus
obtained from the anisotropic consolidation tests. The volumetric yield loci
of lime treated clays are similar in shape and orientation to the limit state
curves for natural clays, presented by MITCHELL (1970). Outside the volumetric
yield locus, the behavior was found to consist of an initial pseudo-elastic phase
(wherein the pore pressure development and volume changes were small), followed
by a stage wherein the behavior appears to be similar to that of a work-hardening
material as the stress paths proceed towards curved failure envelopes. The
treated clays strained-softened after failure , with the residual stress states
lying close to the critical state line of the untreated clay.
The strength and water content relationships were analyzed in terms of the
Critical State concept, and it was found that t he initial, peak and residual
states of treated clays have curved projections on the (q, ~) and water content- effective stress plots. A conceptual mod el to describe the mechanical behavior
of lime treated clay was introduced , in which t he presence of a distortional
yield locus which shifts with t he lime content and curing period was considered.
The conceptual model was t hen used in conjunction with the Revised Theory of
ROSCOE & BURLAND (1968) , specifically to analyze t he work- hardening behavior of
lime treated clays. The strains predicted using the Revised Theory were found
to be in general agreement with the experimentally observed strains. |
| Year | 1990 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. GT-89-02 |
| Type | Dissertation |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Geotechnical and Transportation Engineering (GT) |
| Chairperson(s) | Balasubramaniam, A.S. ;Noppadol Phien- wej ; |
| Examination Committee(s) | Honjo, Yusuke ;Bergado, Dennes T. ;Pichai Nimityongskul |
| Scholarship Donor(s) | The Government of Japan ; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1990 |