Comparison of three test embankments with PVD on soft Bangkok clay | |
| Author | Saha, Janardan |
| Call Number | AIT Thesis no. GE-95-02 |
| Subject(s) | Embankments--Thailand--Bangkok Clay--Thailand--Bangkok |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-95-02 |
| Abstract | The performance of three test embankments namely: TS 1, TS2 and TS3 constructed at Nong Ngu Hao site for Second Bangkok International Airport (SBIA) project has been simulated by finite element method using CON2D and CRISP software to compare the relative performance with respect to settlement, lateral deformation, excess pore pressure variation, and increase in shear strength. Using computer program CON2D, the smear effect has been accounted for. On the other hand, the CRISP, computer program, was used to study the effect of smear and well-resistance. In CON2D, two approaches namely 'Q' adjustment ( equating discharge between axisymmetric and plane strain condition ) and 'Uh' adjustment ( equating degree of horizontal consolidation at every level of foundation soil at every time) are followed to compute 2-D model permeability. Assuming the ratio of horizontal permeability to the permeability in the smear zone (k/ks ) of 10 and the ratio of diameter of smear zone and that of mandrel (dJdm) of 2 are found to yield comparable results. It is seen that 'Uh' adjustment gives comparatively better aggrement with the field data than 'Q' adjustment because of comparatively low model permeability. The construction activities are completed within 226, 238 and 257 days for TSl, TS2 and TS3, respectively. It is also observed that up to the end of construction (EOC), both of these approaches give higher rate of settlement than the field because of a constant value of Poisson's ratio is assumed in the analysis. The very soft clay layer is found to cause 60 to 65% of maximum surface settlement whereas the contribution from medium and soft clay layer is found to be about 27 to 32%. PVD installation with preloading is again reconfirmed as an effective method to accelerate consolidation process with subsequent increase in shear strength. An average of 77%, 83% and 86% of degree of consolidation are observed at 440 days from the start of construction if a PVD length of 10 m with 1.5 m, 1.2 m and 1.0 m spacing in square pattern is used, respectively. It is seen that CRISP considering well resistance and smear, gives better fit to the observed data at the earlier days. |
| Year | 1996 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-95-02 |
| 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. |
| Examination Committee(s) | Balasubramaniam, A.S. ;Noppadol Phien-wej ;Ashford, Scott A. |
| Scholarship Donor(s) | The Royal Thai Government; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 1996 |