Analysis of ground improvement using prefabricated vertical drains with surcharge preloading : a study of the Second Bangkok Chonburi Highway Project | |
| Author | Chishti, Irfan Ahmad |
| Call Number | AIT Thesis no.GE-97-05 |
| Subject(s) | Vertical drains Embankments Second Bangkok-Chon Buri Highway Project |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of the Master of Engineering, School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-97-05 |
| Abstract | The soft Bangkok clay foundation at the Second Bangkok Chonburi Highway Project (SBCH) was improved using prefabricated vertical drains (PVD). Monitoring instrumP-nts such as surface settlement plates, deep settlement plates, inclinometers, piezomuters etc. were installed in the subsoil, in order to observe the deformation behavior under loading. The highway embankment functioned as a test embankment. The Department of Highways, Thailand, arranged for monitoring and documentation of the deformation behavior of subsoil. Using different methods, this monitored record, supplemented with the laboratory test results, was processed in order to predict the in-situ horizontal coefficient of consolidation of soil as well as rate and amount of settlement. The in-situ horizontal coefficient of consolidation was back-calculated by Asaoka's method. The maximum surface settlement was calculated using one-dimensional consolidation theory, Skempton-Bjerrum method as well as Asaoka's method. The degree of consolidation was predicted by Hansbo's theory for radial drainage and one dimensional consolidation theory for vertical drainage. Finally, the perfo1mance of PVD at-site was evaluated. The back-calculated horizontal coefficient of consolidation ranged from 2 m2 /yr to 44 m2 /yr. The rate of settlement predicted by Asaoka's method was in excellent agreement with the observed one, whereas the one-dimensional consolidation method as well as Skempton-Bjerrum method showed some overprediction. In addition, a FEM based computer software, capable of calculating the consolidation of multi-layered soil, named PVD-SD was also used to predict the rate and amount of settlement. It slightly overpredicted the results. Finally, the monitored deformation behavior was compared with the one predicted during the design stage of SBCH. The actual embank.:1ent height was found to be lower than the designed one, resulting in some delay in gaining the required degree of consolidation and, consequently, a delay in project completion. Due to lower embankment height, the elevation of actual embankment after completion of 90% degree of consolidation can be lower than the highest flood level in the region, endangering the highway in case of flooding. Neve1theless, the PVD at SBCH proved to be an effective means of ground improvement. |
| Year | 1998 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-97-05 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Bergado, Dennes T. ;Guey, Lin Der; |
| Examination Committee(s) | Balasubramaniam, A. S.; |
| Scholarship Donor(s) | Government of Japan ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |