A LIQUEFACTION TEST WITHOUT MEMBRANE PENETRATION EFFECTS

概要

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A test system is devised to minimize detrimental effects of membrane penetration on the undrained shear strength of granular soils. The system constituting an electropneumatic closed-loop can compensate for volume changes caused by membrane penetration in real time so that the constant volume of soil skeleton is maintained. It can readily be coupled to any conventional static or cyclic shear test apparatus.In order to evaluate effectiveness of the system, cyclic triaxial tests were performed on specimens 75 mm in diameter either with or without the system. Resulting pore pressure responses and liquefaction strength curves for specimens with and without membrane compliance are compared, and the effects of membrane penetration are discussed. The test results revealed that, while the liquefaction characteristics of a fine sand with a mean grain size of 0.17 mm were not affected significantly by membrane penetration, the cyclic shear stress ratios to cause liquefaction for a coarse sand with a mean grain size of 1 mm were overestimated by about 30% as a result of membrane penetration. These results are consistent with an analytical estimation by other investigators, indicating satisfactory performance of the system in liquefaction tests.
社団法人地盤工学会の論文
1986-12-15