| Summary: | 碩士 === 國立交通大學 === 土木工程學系 === 100 === Because the difficulties involved in field tests in unsaturated soils, we often perform laboratory tests on reconstituted soil samples to determine the mechanical properties of unsaturated soils, such as soil water characteristic curves and shear strength under various matric suctions. However, soil water characteristic curve can be affected by stress state, disturbance, initial void ratio, and moisture content, etc. Characterization of unsaturated soils in situ can be a more desirable approach. Taking advantage of the optic fiber Bragg grating sensing techniques, the author modified an existing pressuremeter to enhance the sensitivity of its strain and pressure measdurement capabilities. A test site was set up within the campus of National Chiao Tung University. A series of field pressuremeter tests were performed in unsaturated soils under various matric suctions. The thesis describes the modifiaction of the pressuremeter and the field test proceduree. The pressuremeter test results are interpreted according to cavity expansion theory considering the effects of matric suction.
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