EXPERIMENTAL STUDY ON THE RELATIONSHIP BETWEEN DEGREE OF SATURATION AND P-WAVE VELOCITY IN SANDY SOILS

摘要

A series of laboratory tests were performed to investigate the effects of the size and roundness of soil particles, relative density, and air bubbles in pore water within sandy soils on the relationship between the degree of saturation (Sr) and P-wave velocity (Vp). We also considered the effect of the degree of saturation on the liquefaction strength of sand. We arrived at the following conclusions based on the test results: (1) the size of soil particles in sand has a strong influence on the B-value-Vp relationship, but a weak influence on the Sr-Vp relationship; the P-wave velocity increases rapidly with increasing degree of saturation from 90 to 100 % for all tested sands; (2) relative density (Dr) has a negligible effect on the Sr-Vp relationship; (3) air bubbles in pore water have a significant effect on both the B-value-Vp relationship and Sr-Vp relationship; (4) based on comparisons of the liquefaction strengths obtained in undrained cyclic triaxial tests on Futtsu sand, we propose that the method of reducing the degree of saturation by injecting air bubbles into sandy ground will prove to be a useful method in terms of mitigating disasters induced by the liquefaction of sand.