| Author | Chai, Jinchun |
| Call Number | AIT Diss. no. GT-91-01 |
| Subject(s) | Embankments
|
| 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-91-01 |
| Abstract | A new analytical method is proposed for determining the grid reinforcement pullout for-ce/pullout displacement curve by using basic backfill soil and grid reinforcement properties. The
pullout skin friction resistance/relative displacement relationship is simulated by linear
elastic-perfectly plastic model. A hyperbolic model has been proposed to represent the pullout
bearing resistance/pullout displacement relationship, in which, the maximum bearing resistance of
single bearing member is determined by a new bearing capacity equation proposed in this paper.
The influences of the grid bearing member spacing ratio, S/D, the bearing member deflection rigidity,
and the pullout softening behavior on the mobilization of pullout bearing resistance are explicitly
included in the proposed model. The concept of load transfer mechanism developed for axially
loaded pile is employed to consider the extensibility of the grid longitudinal member under pullout
loading. Good agreement has been obtained between calculated values and laboratory test results.
Finite element method has been employed to analyze the performance of the reinforced
wall/embankment on soft ground. The salient features of the numerical modelling are: (1) the
interface elements "above" and "below" the reinforcements work as a pair elements, thus, the direct
shear or pullout interaction mode and its corresponding parameters are automatically selected
according to their relative shear displacement pattern; (2) the large deformation phenomenon is
considered by updating the node coordinates including the those of wall or embankment elements
above the current construction level which ensures that the applied fill thickness simulates the actual
field value, and correcting the unbalanced node forces and unit weight of the soil during the consolidation process; (3) the permeability of soft foundation soil is varied during the consolidation
process, and (4) the compaction effect is modelled by hysteretic model (DUNCAN & SEED, 1986).
The AIT full scale test reinforced wall/embankment on Bangkok clay and two trial reinforced
embankments on Muar clay have been analyzed by the proposed finite element model. The
agreement between the finite element results and the field data is quite good. For reinforced wall
on soft ground, the finite element results show that the soil/reinforcement interaction modes not
only influence the performance of the reinforced mass, but also influence the response of the soft
ground. For base reinforced embankment on soft ground, finite element results indicate that the
Tensar grids have negligible effect on the embankment deformation pattern, but the mobilized
tension force in the reinforcement increased the stability of the embankment. The interaction mode
between base reinforcement and soil is controlled by the stiffness of the reinforcement. For low
stiffness reinforcements, such as Tensar geogrids, the direct shear interaction mode is dominant.
On the other hand, for high stiffness reinforcements, such as steel grids, the pullout mode governs
the interaction behavior. The tension forces in reinforcement and lateral displacements of wall face
and the soft foundation soil increase significantly during the soft foundation consolidation process.
Therefore, in simulating the behavior of reinforced earth structures on soft ground, the key factor
to consider is the consolidation of the soft ground. In addition, the varied permeability analysis
yieldeci better predictions on the performance of the reinforced wall/embankment on soft ground. |
| Year | 1992 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. GT-91-01 |
| Type | Dissertation |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical and Transportation Engineering (GT) |
| Chairperson(s) | Bergado, Dennes T. ;Honjo, Yusuke |
| Examination Committee(s) | Balasubramaniam, A.S. ;Worsak Kanok-Nukulchai ;Noppadol Phien-Wej ;Seah, Tian Ho ;Poorooshasb, H. B. ;Rowe, R.K.
|
| Scholarship Donor(s) | The Government of Japan; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1992 |