Characterization of unsaturated residual soils susceptible to rain-triggered landslides from Mae Hong Son Province in Thailand | |
| Author | Zaw Ye Aung |
| Call Number | AIT Thesis no.GE-10-04 |
| Subject(s) | Landslides--Thailand--Mae Hong Son Soil mechanics--Thailand--Mae Hong Son |
| Note | A thesis submitted in partial fulfillment 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-10-04 |
| Abstract | A laboratory experimental investigation was carried out to characterize some residual soils collected from Mae Hong Son Province in Northern Thailand, which are frequently affected by rain-triggered landslides. The program,giving due consideration to the unsaturated natureof the materials,consisted of basic property and index tests on all collected samples, 13in number,and a series of soil water characteristics and performance tests on a 4selected number of samples. Performance tests included a series of saturated flexible wall permeability tests, saturated multi-stage triaxial tests, and suction monitored constant water content confined shear tests in triaxial apparatusand performed on specimens obtained from undisturbed block samples. Modifications as required for constant water content tests were newly made for the triaxial top caps.All samples tested for their particle size distributions were found to exhibit bimodalityin their distribution in varying degrees.The Fredlund et al (2000)equation forbimodal grain size distribution curves is capable of modeling all the grain size distribution with excellent goodness of fit.Soil water characteristic curves obtained from the experimentalprogramalso exhibitsimilar characteristics of bimodality as those of the grain size distributions. Thehysteresisdue to wetting and drying in the soil water characteristic curves are not pronounced.The characteristics of experimental soil water characteristic curves are compared welltoGitirana and Fredlund (2004)modelfor bimodal soil water characteristic curves.Further, an attemptisto predictthe soil water characteristic curves from grain size distribution curvesusing the physic-empirical Arya and Paris(1981)model shows excellentresultswithfitting parameter, ,varying from 0.87to 1.29.The saturated permeability values of the tested samples variedin the range of 10-7to 10-6m/s. The predicted unsaturated permeability function using Jackson’s (1972) statistical model was found todescribetheir overall trend usingtheAverjanov (1950)power model with the fitting parameter varying in the range of 3.3to 3.9. Thesespecimens sheared after isotropic consolidation to effective cell pressures of 100, 200, and 300 kPa exhibited contractive behavior. The results also illustrate that the stress paths are geometrically similar as explained by the critical state concept with q/p' values remaining almost constant. The effective cohesion and friction angles of the selected residual soils variedin the range of 1.6to 12.4kPa and 21 to 32degrees,respectively. Suction monitored triaxial tests revealedthat the shear strength reduction of the tested unsaturated residual soils from the initial unsaturated state to only up to“no suction” state, with the determined saturated and unsaturated effective shear strength parameters can be as much as 47% at imposednet normal stress of 25 kPa.Predictions of the unsaturated effective strength parameter, as proposed byLu and Likos (2006)comparedreasonably well with those obtained from the experiments. |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-10-04 |
| 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) | Bergado, Dennes T.; |
| Examination Committee(s) | Pham Huy Giao;Park, Kyung-Ho;Panich Voottripruex;Apiniti Jotisankasa; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2011 |