Finite element analysis of soft ground improved by prefabicated vertical drains | |
| Author | Kim, Han Ki |
| Call Number | AIT Thesis no. GE-98-22 |
| Subject(s) | Finite element method Soil consolidation |
| 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 |
| Abstract | This study performed a detailed investigation on FEM analysis of unit cells and full scale PVD (Prefabricated Vertical Drain) improved ground with embankment surcharge loading. Interface element was introduced to simulate ve1tical drain with finite permeability to take well resistance into consideration. Based on equivalent discharge rate under confined flow condition, an equivalent horizontal permeability was determined to consider smear effect. Fmthermore, FEM analysis incorporated with the proposed matching schemes were performed on axisymmetric unit cell. The numerical results were compared with the theoretical solutions from Zeng (1988). Excellent agreements are found in comparisons. Consequently, the effectiveness of the proposed matching schemes is identified. A series of parametric studies based on the proposed matching scheme, were performed for two layered unit cell and the evaluation of well resistance. The numerical results of two layered unit cell were compared with the theoretical solutions from Onoue (1988). Excellent agreements further identify the applicability of the proposed matching schemes to the multi-layered ground improved by PVD. However, according to the numerical results, the well resistance factor proposed by Hansbo (1979) overestimates the well resistance of vertical drain with shorter installation length. In addition, the proposed matching schemes were employed to convert actual radial flow to two-dimensional plane strain flow based on the equivalent average degree of consolidation and discharge capacity of vertical drain. Well resistance is automatically considered by interface elements, which possesses equivalent discharge capacity to vertical drain in axisymmetric case. Meanwhile, the smear effect proposed by Hird et. al (1992) was also included in the analysis. Eventually, the proposed matching schemes were applied to full scale PVD improved ground with embankment surcharge loading. The evaluation of well resistance was carried out in term of consolidation rate. The numerical results show that significant well resistance existed during consolidation process in the full scale test embankment. |
| Year | 1999 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Der Guey, Lin; |
| Examination Committee(s) | Bergado, D. T.;Noppadol Phienwej; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1999 |