• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.3
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• pp.91-100
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• 1999

Tow constitutive models for weathered granite soil, Yasufuku's constitutive model with a single yield surface and Lade's constitutive model with two intersectiong yield surface compared in terms of their capabilities to accurately capture the observed behavior of compacted weathered grainite soil for various stress-paths. Both the single surface and the double surface models capture the experimentally observed behavior at a variety of stress-paths with good accuracy. The double surface model may model the observed compacted weathered granite soil behavior with better accuracy for proportational loading with increasing stress, but the single surface model may model dilatancy property with better accuracy for p-constant loading with increasing stress ratio.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.2
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• pp.70-79
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• 1999

The lower ground of structure, in which the strip loads, such as earth dams and embankments , are signiificantly working on , is required to be interpreted as a state of plane strain where the strain of intermediated principal stress direction is put '0' . The plane strain state is frquently observed in actural soil engineering case. For those case, drained stress-strain and strength behavior of Iksan weathered granite soil prepared in cubical specimens with cross-anisotropic fabric was studied by conventional triaxial compression, plane strain and cubial triaxial tests with independent control of the three principal stress. All specimens were loaded under conditions of principl stress directions fixed and aligned with the directions of the material axes. As a result of research , when a ground condition is analyzed under plane strain state, the shear strength obtained from the conventional triaxial compression test can be understimated.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.43-55
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• 1999

This study evaluated Yasufuku's constitutive model in terms of its capability to accurately consider the observed behavior of Iksan compacted weathered granite soil for various stress-paths. The strains calculated from the model are in reasonable agreement with those measured, but some discrepancies occur. The largest differences between measured and calculated strains occur for axial strain of proportional loading with increasing stress. Yasufuku's constitutive model can consider the observed behavior of Iksan compacted weathered granite soil with accuracy for conventional triaxial compression and for p'-constant loading with increasing stress ratio.

• Geotechnical Engineering
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• v.10 no.3
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• pp.55-78
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• 1994

Decomposed granite soil is a Granitic Gneiss, and it is a c Korean peninsula. It is known a changed significantly when it is aim of this study is to evaluat utility of the constitutive laws. Firstly, triaxial tests were pe sites prepared by the laborato scrutinized the characteristics results were analysed and the p evaluated. Finally, the predicted Even though the origins of slight difference in the angle of pression line( A) : both soils show In the effective mean normal uniqueness of the Normal Compr The relationships between the the decomposed granite soil tier OCR is larger than 2, the stress stress(MDS) or. even thous moved below the theoretical Ros was found to coincide with the (NC) soils, the pore pressure parameter, A,, increased up to 1.3. This phenomenon might be mainly due to the effect of the particle crushing during shearing, When the OCR value approaches 7, the negative pore pressure is developed in undrained tests and the dilatancy is observed in drained tests. The predicted and the observed behavior of drained tests showed relatively good fitting with the Cam-Clay model.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.6
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• pp.64-73
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• 1996

The three-dimensional strength behavior of compacted decomposed granite soil was studied using cubical triaxial tests with independent control of the three principal stresses. All specimens were loaded under conditions of principal stress direction fixed and aligned with the directions of compacted plane. For comparable test conditions, the major principal strain and volume strain to failure were smallest when the major principal stress acted perpendicular to the compacted plane. The opposite extremes were obtained when the major principal stress acted parallel to the compacted plane. In cubical triaxial tests with same b values and with ${\theta}$ values in one of three sectors of the octahedral plane, independent of the range of ${\theta}$, higher friction angles are obtained in tests with b greater than in triaxial compression tests in which b 0.0, Comparison between the results of the drained cubical triaxial tests on lksan compacted decomposed granite soil and the cross section of the Mohr-Coulomb failure surface as well as the cross section of the Mohr-Coulomb failure surface were made. Lade's isotropic failure criterion based on vertical specimens overestimates the strengths for tests performed with values of 0 between 90˚ and 1 50˚ the Mohr-Coulomb criterion generally underestimates the strengths of tests performed with values of ${\theta}$ between $0^{\circ}$ and $180^{\circ}$ except around the $120^{\circ}$.

• Geotechnical Engineering
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• v.13 no.4
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• pp.177-198
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• 1997

Since decomposed granite soil shows various characteristics of shear behavior dependent on initial conditions such as weathering degree and grain breakage, it is nacessary to invert ligate stress -strain relationship and changes of shear characteristics for different initial conditions. Associated with abovefnentioned view, direct shear tests, and triaxial compression tutsts(Ef, CD) were carried out in this study for undisturbed and disturbed compacted weathered granite samples obtained from 4 construction work sites with the various weathering degree and components of parent rocks. The deformation behavior of undisturbed samples under small confining stress shows hardening to softening, which is similar to that of over nsolidated clay whereas disturbed weathered granite soils do hardeningfonstant regardless of weathering degree, which is also similar to sedimentary clay. Conventional direct shear-tests for undisturbed samples show a tendency to overestimate cohesion. It is possidle to approximate stress ratio(q/p') and volumetric increment ratio(dv/ds) in the triaxital compression tests by an equation, ($dv/d\varepsilon,=\alpha(M-\eta))$ irrespective of moisture content, weathering degree and disturbance.