Evaluation of the second soft ground improvement using Vacuum-PVD on the third runway extension (zone 3) at The Suvarnabhumi International Airport | |
| Author | Rementilla, Jansen Torres |
| Call Number | AIT Thesis no.GE-21-01 |
| Subject(s) | Airports--Construction--Thailand--Bangkok Vertical drains--Thailand--Bangkok Vacuum technology Clay--Thailand--Bangkok Suvarnabhumi (Airport : Bangkok, Thailand) |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geotechnical and Earth Resources Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | This manuscript presents the analysis of the 2nd improvement of soft Bangkok clay in the 3rd runway of Suvarnabhumi Airport (Zone 3) using vacuum-PVD with surcharge embankment. This study is divided into three main parts: (1) Field Investigation, (2) Laboratory Testing and, (3) Geotechnical Analysis. In the field investigation, upon reaching the 90% degree of consolidation in 208 days, the vacuum pumping was terminated causing a surface settlement of 759 mm to 808 mm causing an average rebound settlement of 35 mm. Due to the vacuum pressure of more than 70 kPa and 1m surcharge load, the excess pore water pressure generated at -5.00 m and -10.00 m resulted in -65 kPa to -73 kPa and -40 kPa to -57 kPa respectively. Inward lateral movements of 250 mm to 278 mm also occurred due to the vacuum pressure being higher than the surcharge load. Ground cracks 6 m away from the side of the trench were also observed due to vacuum pressure greater than horizontal stress. The laboratory testing included the quality check of materials for PVD filter and drain, geotextile and geomembranes which all passed the provided specifications. After vacuum-PVD improvement, soil samples from the site were subjected into various testing and the soil property changes included water content reduced by 24%, liquid limit reduced by 11%, plastic limit reduced by 15%, undrained shear strength increased by 40%, and preconsolidation pressure increased by 30%. Deformation properties such as CR decreased by 36% and eo also decreased by 30%. The soft to medium stiff clay layer has transformed into medium stiff clay. Geotechnical analysis included the degree of consolidation assessment using different methods and Asaoka’s method was proven to be the most accurate method compared to Hyperbolic and using of porewater pressure data. With this, the back-calculation of Ch value was performed and resulted into 4.08 to 4.30 m2/year using kh/ks = 4 and ds/dm = 2. Moreover, the FEM simulation was performed, and the soil parameters has been successfully calibrated to match the field observed data. The calibrated FEM model was used to show the differences in settlement and time rate by changing PVD spacing and length. Results found that the longer the spacing, the longer time it takes to consolidate. In addition, extending the PVD length results in extra settlement due to additional vacuum load and the time to achieve 90% DOC would be shortened. However, in the case of changing both spacing and length, spacing greatly affects time rate and combining these designs would take longer time to reach 90% DOC. |
| Year | 2022 |
| 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) | Chao, Kuo Chieh;Bergado, Dennes T. (Co-Chairperson); |
| Examination Committee(s) | Avirut Puttiwongrak;Baez, Francisco; |
| Scholarship Donor(s) | Asian Institute of Technology Partial Scholarship; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2022 |