Ground deformation associated with deep excavation in soft clay | |
| Author | Trinidad, Inocito A. |
| Call Number | AIT Thesis no. GE-01-10 |
| Subject(s) | Clay--Analysis Numerical analysis Excavation--Simulation methods |
| Note | A thesis submitted in partial fufillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-01-10 |
| Abstract | A numerical simulation of a double propped wall vertical excavation in normally consolidated soft clay was carried out in this study. The excavation considered is a prototype of a centrifuge model test excavation. A finite element program DACSAR (Deformation Analysis Considering Stress Anisotropy and Reorientation) that implements the Sekiguchi and Ohta (1977) elasto-viscoplastic constitutive model for normally consolidated clay was used in the numerical analysis. Lateral movement of the retaining wall, settlement of the ground surface behind the wall, earth pressures acting on the wall and pore water pressures on the prototype ground were predicted. The effects of propping and preloading on the associated deformation behavior of the ground and wall during excavation were carefully studied. Special attention was given to the effect of timing and depth of excavation during preloading. The effects of embedment of the retaining wall into the bottom sand layer on the behavior of ground and wall movements were also studied. The results of FEM prediction were found in close agreement with the measurements and observation in the centrifuge model test. Predicted lateral wall movement, lateral earth pressure distribution, and pore water pressure at various zones of excavation match very closely with the measurements in the centrifuge model. Settlement patterns were similar to that in the physical model however, the magnitude of settlements were underestimated near the wall and overestimated away from the wall. The main reason for this difference is attributed to the capability of the constitutive soil model to simulate small strain stiffness. It was found that even 1-m embedment into sand layer could significantly increase the stability of excavation. Under this condition deformation becomes the main concern in the analysis and design instead of stability. Preloading and the early timing of propping can effectively control the increase in lateral deformations and settlement. However, it is difficult to recover deformations once it has occurred by increasing the preloading. Hysteresis and non-linear behavior of the soil is considered to be one of the main reasons of the irrecoverable deformation. |
| Year | 2002 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-01-10 |
| 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) | Takemura, Jiro; |
| Examination Committee(s) | Noppadol Phien-wej;Park, Kyung-Ho; |
| Scholarship Donor(s) | University of San Carlos;Netherlands Organization for International Cooperation in Higher Education (NUFFIC); |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2002 |