In Korea, granite is abundant and occupies around one-third of the country, and granite weathered residual soils, which is called 'Masado', is widely distributed. The soil is visually described as a sandy or gravelley soil, but the behavior is quite different from the behavior of usual sand and gravel. Undisturbed sampling of this soil has been extremely difficult because of the particle structure, and this difficulty have kept the researchers from investigating the deformational characteristics of granite weathered residual soil.
The purpose of this research is to determine the stress-strain relationships of the undisturbed and statically compacted granite weathered soils of different degree of weathering. A special undisturbed sampling device was developed and undisturbed samples were obtained for triaxial compression (TX), resonant column (RC), and torsional shear (TS) tests. Local deformation transducer (LDT) was developed for the internal strain measurements during TX test. Both undisturbed samples and statically compacted samples of same density were tested using TX with LDT, RC, and TS tests.
The stress-strain relations of granite weathered soils were determined in a wide range of strain amplitude from $10^{-4}$% to 1% by combining various test results. Moduli obtained from different testing techniques matched very if the effect of strain amplitude was considered in the comparison. The stiffness and strength decreased with increasing the degree of weathering. The stiffness of statically compacted specimens was lower than that of undisturbed one, whereas the shear strength of statically compacted specimens was slightly higher than that of undisturbed one.
