| Author | Wanittapon Wongprasan |
| Call Number | AIT Thesis no.GE-09-06 |
| Subject(s) | Vertical drains--Simulation methods
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering Geotechnical and Geoenvironmental Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-09-06 |
| Abstract | This study presents the finite element simulations of reconstituted soil specimens and in¬situ soil improved with PVD combining vacuum as well as heat preloading. In the laboratory, the results oflarge consolidometer tests of reconstituted Bangkok soil samples were back -calculated and simulated. In case of PVD, a surcharge of 100 kPa was applied. The simulation showed that the settlements reach 91 % degree of consolidation correspondi.ng to 113.9 mm within period of 47 days with the ratio of horizontal permeability at undisturbed zone to horizontal permeability at smear zone, kh/ks, is 3. The back-calculation of the horizontal coefficient of consolidation, Ch, is 1.93. In case of Vacuum-PVD, a surcharge of 50 kPa combining vacuum pressure of -50 kPa were applied. The simulation showed that the settlements reach 92% degree of consolidation corresponding to 114.8 mm within period of 42 days with kh/ks value is 2.7. The back-calculation of Ch value is 2.23. In case of Thermo-PVD, a surcharge of 100 kPa combining temperature of 90°C was applied. The simulation showed that the settlements reach 99.3% degree of consolidation corresponding to 142.8 mm within period of 28 days with kh/ks value is 1.4. The back-calculation of Ch value is 4.17. In case of Thermo-Vacuum-PVD, a surcharge of 50 kPa combining vacuum pressure of -50 kPa and temperature of 90°C were applied. The simulation showed that the settlements reach 99.8% degree of consolidation corresponding to 146.7 mm within period of 28 days with kh/ks value is 1.1. The back-calculation of Ch value is 4.38. In the field conditions, at Second Bangkok International Airport, two cases of conventional PVDs and Vacuum-PVDs were observed. In case of conventional PVDs, embankment was constructed into 3 stages up to 3.8 m height and installed rectangular pattern with spacing of 1 m and depth 10m. Observed settlements of 1.28 and 1.58 m were obtained with 376 and 382 days, respectively. The back-calculation and simulation of Ch value is 2.62 and 2.37 with kh/ks value are 9.2 and 10. In case of Vacuum- PVDs, embankment was constructed into 2 stages up to 2.8 m height combining vacuum pressure of -60 kPa and installed triangular pattern with spacing of 0.85 m and depth 10m. Observed settlements of 1.38 and 1.55 m were obtained with 260 days at two locations. The back-calculation and simulation of Ch value is 3.56 and 4.83 with kh/ks value are 7.3 and 10. at the campus of the Asian Institute of Technology, The cases of conventional PVDs and Thermo-PVDs were observed. In case of conventional PVDs, embankment was constructed into 1 stage up to 6 m height and installed rectangular pattern with spacing of 1 m and depth 8 m. Observed settlements of 239.5 mm was obtained with 207 days. The back-calculation and simulation of Ch value is 6.69 with kh/ks value is 6.2. In case of Thermo-PVDs, embankment was constructed into 1 stage up to 6 m height combining temperature of 75°C and installed rectangular pattern with spacing of 1 m and depth 8 m. Observed settlements of 390 mm were obtained with 207 days. The back-calculation and simulation of Ch value is 8.51 with kh/ks value is 4.1. FEM simulations and back-calculations revealed that Vacuum-PVD is faster than PVD both in the laboratory and field conditions due to the reduce effect of smeared zone and increased coefficient of consolidation during vacuum preloading and Thermo-PVD is more settlement than PVD both in the laboratory and field conditions due to the temperature increase because the viscosity of the pore water reduce |
| Year | 2010 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-09-06 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Bergado, Dennes T.; |
| Examination Committee(s) | Park, Kyung Ho;Pham Huy Giao; |
| Scholarship Donor(s) | ASEAN Foundation;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2009 |