Modeling of hexagonal wire reinforcement and 2D/3D simulation of full scale embankment | |
| Author | Chairat Teerawattanasuk |
| Call Number | AIT Diss. no.GE-03-03 |
| Subject(s) | Embankments Soil mechanics Soils--Testing |
| Note | A disse1iation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. GE-03-03 |
| Abstract | The "conventional pullout tests" were conducted on hexagonal wire mesh embedded in Ayutthaya sand to investigate the soil reinforcement interaction. Two types of hexagonal wire mesh were tested; namely: (a) galvanized (zinc-coated) and (b) PVCcoated. The failure mechanism of both types of the reinforcement differs depending on cell size aperture, reinforcement stiffness, reinforcement material, fill material, and vertical normal stress. The empirical equations for predicting the maximum pullout load, Pmax, as a function of normal pressure, CTv, has been developed. A new analytical model for predicting the pullout resistance of hexagonal wire mesh reinforcement has been proposed under the conventional pullout condition. The relationship between the friction resistance and relative displacement relationship of a hexagonal wire mesh can be simulated by a linear elastic- perfectly plastic model. The passive bearing resistance of an individual bearing member can be modeled by a hyperbolic function. Under the "conventional pullout test'', a "necking phenomenon", which greatly reduced the pullout resistance, occurred during the pullout process. To investigate the necking effect on the hexagonal wire mesh samples, the pullout clamping system was installed inside the pullout box with confinement from the fill materials hereinafter called "in-soil pullout test". The necking phenomenon during the "insoil pullout test" can be greatly reduced to negligible amounts. The predicted total pullout resistance for zinc-coated hexagonal wire mesh is approximately 20% greater than PVCcoated hexagonal wire mesh at the applied normal pressure due to the higher stiffness, EA, and higher shear stiffness, ks, of the former than the latter.Under "in-soil pullout" condition, a new analytical model for the pullout resistance of hexagonal wire mesh reinforcement has also been proposed. In finite difference modeling of "in-soil pullout tests", the values of interaction coefficient, R, applied were 0.90 and 0.65 for zinc-coated and PVC-coated hexagonal wire meshes, respectively. The predicted pullout resistance results from finite difference modeling reasonably agreed with the results from laboratory tests as well as the results from the analytical modeling. The modeling of hexagonal wire mesh reinforcement as a rough sheet elements or shell structural elements can combine the bearing resistance on transverse members and frictional resistance on both transverse and twisted members. Two existing full scale test embanlanents; namely: steel grid and hexagonal wire mesh reinforced embankments, were selected to be the reference cases for comparisons between the predicted results obtained from numerical analyses and the measured field data. The 2D and 3D numerical modeling based on finite difference method were carried out to investigate the influence of the boundary conditions applied in the numerical analyses. The 2D numerical analysis simulated the overall behavior of the steel grid reinforced embanlanent system with more reasonable agreement between the field measurement and the predicted values compared to 3D numerical analysis. The 3D numerical analysis yielded closer the overall behavior of the hexagonal wire mesh reinforced embankment than the 2D numerical analysis. The actual behavior of the steel grid reinforced embanlanent with longer plan dimensions and the actual behavior of the hexagonal wire mesh reinforced embankment with shorter plan dimensions corresponded well to the 2D case and the 3D case, respectively. The di<;crepancy between the predicted results and the measured field data may be caused by the exclusion, for reasons of simplicity, of the seasonal variations of the groundwater level. Finally, the effects of boundary conditions (2D or 3D) applied in numerical analysis should be considered as important factors that may affect the numerical results. |
| Year | 2003 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. GE-03-03 |
| Type | Dissertation |
| School | School of Civil Engineering |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Bergado, Dennes T.; |
| Examination Committee(s) | Park, Kyung-Ho; Pichai Nimityongskul;Hayashi, Shigenori ; |
| Scholarship Donor(s) | Government of Austria; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2004 |