FLOW POTENTIAL OF SANDY SOILS WITH DIFFERENT GRAIN COMPOSITIONS

抄録

The flow deformation or strain softening in undrained shear of saturated sand is discussed in this paper. When evaluating the flow of field deposits, the prime issue to be addressed is whether the soil in its in-situ state has the potential to develop flow deformation or not. This paper presents a rational method which allows for such an assessment to be made and aims at quantifying the effects of grain-size distribution on the flow potential of sandy soils. On the basis of existing laboratory and field test results on sandy soils, a flow potential formulation was developed within the framework of the state concept. Here, the SPT blow count was used as a parameter for field characterization of sand deposits whereas the void ratio range (e_max-e_min) was employed as a measure indicative of the grading properties of sandy soils. It is shown that sands with a large value of void ratio range have a high flow potential, indicating that fines-containing sands are more susceptible to flow than clean sands. Results of this study also suggest that flow with zero residual strength is limited to field deposits with a very low SPT blow count, and that soils with a void ratio range of less than 0.35, such as coarse sands and gravels, are practically safe against flow with zero residual strength.