Threshold stress and plastic settlement for high-speed railway foundation on over-consolidated clay under cyclic loading | |
| Author | Mudden, Falis |
| Call Number | AIT Thesis no.GE-19-09 |
| Subject(s) | Railroad tracks--Foundations--Thailand High speed trains--Thailand--Design and construction |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Geotechnical and Earth Resources Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Presently, the construction of the high-speed railway in Thailand is being constructed having the maximum speed at 250 km/hr. in order to have the efficiency of transporting goods and passengers with a total length of more than 1,000 km long. The behavior of soil foundation under cyclic loading conditions induced by high-speed trains should be studied and emphasized rather than a conventional train because of higher speed and a hence higher vibration that will surely affect the adjacent structure and subgrade soil. The cyclic loading increases the excess pore water pressure and could cause progressive shear failure (general subgrade failure) and settlement. Therefore, it is very important to study the behavior of the railway foundation and determine the threshold stress to avoid the problems (stress and settlement) caused by high-speed trains. Some parts of the Thai high-speed train project will be constructed on the Bangkok soft clay, which is normal and over-consolidated. The normal-consolidated Bangkok soft clay has been studied by Supavat, a former student. In this study, the threshold stress and plastic settlement behavior are focused on over-consolidated Bangkok soft clay. The sample collection and laboratory tests have been done in the Asian institute of technology. The triaxial tests have been performed with a variation of the over-consolidation ratio of 2 and 4 and a frequency of 2 Hz and 4 Hz. The threshold stresses of all cases were investigated showing that when the Bangkok soft clay was applied by cyclic stresses, the strength of Bangkok soft clay reduced by 30% of the strength when applied by static stresses. Therefore, the threshold stress of Bangkok soft clay is about 70% of peak monotonic strength. The plastic deformation of Bangkok soft clay was also observed by the results of all tests done. Moreover, the numerical model of Thai high-speed train was generated in PLAXIS2D for studying the behavior of the settlement under cyclic loading from the high-speed train and for comparison to the experimental tests. The numerical analysis showed that the development of the plastic settlement in the numerical model is dependent on the velocity or frequency of the train. The threshold stress obtained by the laboratory worked was used to predict the safety of the Bangkok soft clay foundation in numerical modeling. |
| Year | 2020 |
| 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; |
| Examination Committee(s) | Seah Tian Ho;Pham Huy Giao; |
| Scholarship Donor(s) | His Majesty the King’s Scholarships (Thailand); |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2020 |