ROLE OF FINES ON UNDRAINED CYCLIC SHEAR STRENGTH AND RELATIVE DENSITY OF DECOMPOSED GRANITE SOIL "MASADO"

Abstract

 A series of undrained cyclic triaxial tests was performed on reconstituted decomposed granite soil Masado sampled from two sites. The liquefaction strengths of these Masado were almost constant when the relative density was less than 80% and they increased markedly when the relative density exceeded 100%. This was believed to be due to the fact that the relative densities were calculated based on conventional minimum and maximum density tests specified for clean dry sands whereas Masado contains non-plastic fines and volume reduction occurred during saturation. In the present study, minimum and maximum density tests were carried out using wet samples and the results were used to re-define the new relative density of the material. The relationship between liquefaction strength and the re-defined new relative density showed good correlation, with Masado showing similar trend in behavior with relative density as Toyoura sand. With the proposed method of using a re-defined relative density, a better understanding of the relation between liquefaction strength and relative density of decomposed granite soil containing fines was obtained.