BEHAVIOR OF LIQUEFIED SANDS UNDER EXTREMELY LARGE STRAIN LEVELS IN CYCLIC TORSIONAL SHEAR TESTS
BEHAVIOR OF LIQUEFIED SANDS UNDER EXTREMELY LARGE STRAIN LEVELS IN CYCLIC TORSIONAL SHEAR TESTS
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DOI：
10.3208/sandf.48.727
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发表时间：
2008-10
影响因子：
3.7
通讯作者：
T. Kiyota;Takeshi Sato;J. Koseki;M. Abadimarand
中科院分区：
文献类型：
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作者：
T. Kiyota;Takeshi Sato;J. Koseki;M. Abadimarand
为了研究液化砂土在高达100%左右的双振幅剪应变的超大应变水平下的循环特性，对不同密度的饱和丰浦砂、两种原位冻结桑迪试样及其重塑试样进行了一系列保持试样高度不变的不排水循环扭剪试验。对膜力对实测剪应力的影响进行了适当的修正。当总剪应变超过一定值后，试件的变形变得不均匀，这在本研究中被称为“应变局部化”。这种局部化的开始与偏应力的循环幅值和剪应变增量的变化有关。在丰浦砂的情况下，开始应变局部化的剪切应变的极限值被发现，随着相对密度的降低，这样的趋势是一致的，当相对密度高于30%的土壤液化的经验关系。原位冻结桑迪试样的极限剪应变值小于重塑试样的极限剪应变值，表明在不同程度的自然老化作用下，其土体结构性存在差异。
In order to study the cyclic behavior of liquefied sands at extremely large strain levels up to double amplitude shear strain of about 100%, a series of undrained cyclic torsional shear tests while keeping the specimen height constant was performed on saturated Toyoura sand under different densities, two kinds of in-situ frozen sandy samples and their reconstituted specimens. Due correction was made for the effect of membrane force on the measured shear stress. After exceeding a certain level of overall shear strain, the specimen deformation became non-uniform, which is called as “strain localization” in the present study. The initiation of such localization was associated with the changes in the cyclic amplitude of deviator stress and the increment of shear strain. In the case of Toyoura sand, the limiting value of shear strain to initiate strain localization was found to increase with decrease in the relative density, and such a trend was consistent with the empirical correlation of soil liquefaction when the relative density is higher than 30%. In the case of in-situ frozen sandy samples, their limiting shear strain values were smaller than those of the reconstituted specimens, suggesting that their soil structures were different from each other under different degrees of natural aging effects.