Laboratory shear tests on rate-dependent nature of liquefied sand undergoing large deformation

目前的研究已经被证明是为了验证有液体的沙子，而且它有一种与速率相关的自然，而且很好地直接衡量了视觉效果。这一目标已经成为一个重要的因素，因为预测的流动诱导的沙子地面变形，迫切需要的是安全的生命线设施，就像河流和港口结构一样。模型测试是由许多研究机构执行的，这些研究机构已经获得了视觉的目标和若干价值观。这种研究的缩短是因为模型测试不能直接衡量压力和液体沙子的压力，以及视觉的价值不能从测试结果中返回计算。用这个观点，目前的研究启动了实验室的剪切测试来衡量视觉。在第一阶段，一个空心的圆锥形挤压切割装置被安装得很成功。从它那里学到的一课;-一个令人难以置信的特别指定形式的水电影在其顶部和间接的torsion shear becomes difficult。- Moreover是一个真正的液体状态，因为混乱的真实状态是不可能发生的，因为在未定义的条件下，会增加有效的压力和造成严重的压力。确切地说，第二阶段的研究在特定的一个可能的水电影中使用的三重压缩测试是不影响压缩力加载的。莫弗，它已决定在一幅排水的画布上运行测试，同时控制土壤压力高而有效的压力低。研究中的主要发现;-液体沙子的可见性协同作用在500至4000千帕的范围内。一种干燥的物质展示了一个较小的可见性，建议说，水饱和的物质中约有50%的可见性是由pore水产生的;可能在pore水中以移动的沙子和谷物发挥重要的角色，允许的沙子和有一个较小的可见性比统一分级的沙子。

The present study has been attempting to verify that liquefied sand has a rate-dependent nature, as well as directly measuring the viscosity coefficient. This aim has been important because prediction of liquefaction-induced deformation of sandy ground is urgently needed for safety of lifeline facilities as well as river dikes and harbor structures. Model tests have been conducted by many research institutes for this goal and several values of viscosity have been obtained. The shortcoming of this way of study is that model tests cannot directly measure the stress and strain of liquefied sand, and the values of viscosity as back calculated from test results cannot be examined.With this view point, the present study initiated laboratory shear tests for measuring the viscosity. In the first stage, a hollow cylindrical torsion shear device was employed with little success. The lesson learned from it are ;- A liquefied specimen forms a water film at its top and consequently torsion shear becomes difficult.- Moreover, the true state of liquefaction cannot be attained because of dilatancy which under undrained conditions increases the effective stress and makes sand stiff. Accordingly, the second stage of study employed triaxial compression tests in which a possible water film at the specimen ユs top did not affect loading of compressional force. Moreover, it was decided to run tests in a drained manner while controlling artificially the pore pressure high and effective stress low.The major findings from the study are ;- The viscosity coefficient of liquefied sand is in the range of 500 to 4000 kPa.- A dry specimen exhibits a smaller viscosity, suggesting that about 50% of viscosity in a water saturated specimen is generated by pore water ;probably vortex in pore water among moving sand grains plays an important role.Alluvial sand with fines has a smaller viscosity than uniformly graded sand.