| Summary: | 博士 === 國立成功大學 === 土木工程學系碩博士班 === 92 === Two special properties of granular soils are investigated in this study. Dilative behavior of soil has been found. It is very important when analyzing critical or ultimate states of granular soils. However, a lack of this type report has been reported to identify the dilative behavior of granular soils, especially at low confining pressure. In an effort to study the dilative behavior of granular soils, this study performed numbers of triaxial tests on various types of granular soils. Test results indicated that dilation angles were much higher than those suggested by previous literatures. In addition to the laboratory work, this study also verified the test results using numerical analysis based on a finite difference computer program. Results of the numerical analysis showed that predictions of stress-strain relationships of granular soils were obviously improved when actual dilation angles were applied. Besides, the behavior for the artificially cemented granular soils is also investigated in this paper. Blast furnace slag cement is used in the test and compared with ordinary Portland cement. As the cement content increases, both peak strength and initial stiffness increase. Besides, cemented soils are required significantly a larger number of cycles to cause initial liquefaction and 5 % to 10 % shearing strain cyclic mobility under cyclic loading condition and for a given cyclic stress ratio. Cementation increases the shear modulus and decreases damping ratio of sand under high strain amplitudes in a variety of confining pressures. The performances of blast furnace slag cement are regarded as well as ordinary Portland cement.
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