Cyclic loading response of Fraser River sand for validation of numerical models simulating centrifuge tests
Cyclic loading response of Fraser River sand for validation of numerical models simulating centrifuge tests
复制标题
弗雷泽河沙的循环加载响应，用于验证模拟离心机测试的数值模型
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
S. Sriskandakumar
中科院分区：
文献类型：
--
作者：
S. Sriskandakumar
采用U B C直剪试验装置对弗雷泽河砂的循环荷载响应进行了试验研究。一个简单的空气pluresolvement的方法来重建实验室砂样复制离心标本中预期的土壤结构。恒体积（不排水）进行了测试和不初始静态剪应力条件下，在松散和致密的密度状态。虽然所观察到的机械响应的趋势是相似的，松散的airpluviated样本更容易在循环载荷下液化比水pluviated对应。两种样品重构方法产生的差异可归因于颗粒结构的差异，这清楚地突出了组构效应在砂的机械响应评估中的重要性。由于增加围压（应力致密化）的致密化显着增加了松散的空气-pluviated砂的循环阻力，具有强烈的影响，从离心试验的观察结果的解释。然而，这种影响并不突出的情况下，水pluviated或密集的样品。初始静态剪切应力降低了在简单剪切加载的松散的空气-pluviated砂的循环剪切阻力，相反，从三轴试验的数据的基础上报告的电阻增加。在初始静剪应力的存在下，密实砂的循环阻力增加。先前的循环荷载产生高的超孔隙水压力（或显著的剪切应变），降低了砂土对未来循环荷载的抗液化能力，
Cyclic loading response o f Fraser River sand was investigated using the U B C direct simple shear (DSS) device as input to numerical simulation o f centrifuge physical models. A simple air-pluviation method was developed to reconstitute laboratory sand samples replicating the soil fabric anticipated in centrifuge specimens. Constant-volume (undrained) tests were conducted with and without initial static shear stress condition at loose and dense density states. While the observed trends in mechanical response were similar, the loose airpluviated samples were more susceptible to liquefaction under cyclic loading than their water-pluviated counterparts. The differences arising from the two sample re-constitution methods can be attributed to the differences in particle structure, clearly highlighting the importance of fabric effects in the assessment of the mechanical response of sands. Densification due to increasing confining stress (stress densification) significantly increased the cyclic resistance of loose air-pluviated sand with strong implications in relation to the interpretation of observations from centrifuge testing. This effect, however, was not prominent in the case of water-pluviated or dense samples. The initial static shear stresses reduce the cyclic shear resistance of loose air-pluviated sand in simple shear loading, in contrast to the increase in resistance reported based on data from triaxial testing. Dense sands indicated a increase in cyclic resistance in the presence of initial static shear stress. Previous cyclic loadings generating high excess pore water pressures (or significant shear strains) reduced the liquefaction resistance of sand against future cyclic loading, while