Behaviors of soil structure in shearing zone by the ring shear test and its characteristics

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In this research, two kinds of results are obtained as follows, although comparisons between strain-controlled and stress-controlled ring shear test characteristics are omitted in final report, because the latter test adjustment have made much time.(A) Characteristics of ring shear test for sandy soils(1) The magnitude of ring shear strain is necessary to 0.5-1.0 for sandy soils and 0.5 for coarse sand.(2) Adjustment of shearing strength by volume strain as dilatancy for sandy soil at the ring shear test isn't so great in comparison with the adjustment for silty soils.(3) Composition of fine and coarse sand particles makes effect on shearing resistance. The more the coarse particles fraction is, the greater the strength of sandy soil specimen is.(4) Friction between coarse sand and mineral board is not so great against the expectation of empirical engineers.(5) The strength of sandy soils by direct shear test result is thought to be too great for design purpose compared with ring shear test, and the ring shear test is better even for sands.(B) Estimation of soil structure in shear zone by pore diameter distribution(6) Using the soil moisture retention curve, we can get the distribution of void diameter, which is called as the "moisture method".(7)The most frequent void diameter of sands after shear turns to be slightly greater than before shear, for example, as a diameter in 0.075 mm turns to 0.085 mm for fine sands.