Movement of surface nonliquefied ground caused by liquefaction-induced flow and its effect to structures

在拉伸荷载作用下，得到了地表未液化土在剪切诱导流动过程中作为土块运动的特性。利用空心扭剪仪进行了新鲜试验和阶段试验。研究发现，即使在循环荷载作用下，抗拉强度也约为抗压强度的1110倍。此外，小菌株的新鲜测定和阶段测定之间存在一定差异，但大菌株的新鲜测定和阶段测定之间没有差异。这两个结果表明，在评价表层非液化土的拉伸特性时，荷载历史的影响可以忽略不计。将该力与传统设计中考虑的水平力（如惯性力）进行比较。一个案例研究使用的土壤剖面在港口岛发生显着的扰动诱导流。计算是以结构的尺寸为参数进行的。结果表明，当断面形状接近正方形时，常规设计中考虑的水平力要大于冲流引起的力，而当断面宽深比增大时，冲流引起的力要大得多，这表明必须重新考虑冲流的补救措施。

Behavior of surface unliquefied soil that moved as a soil block during liquefaction-induced flow is obtained under the tensile loading condition. Both fresh test and stage test are made by means of hollow torsional shear test apparatus. It is found that tensile strength is about 1110 of the compressive strength even under the cyclic loading. In addition, although there are some difference between fresh and stage test at small strains, there is no difference between them at large strains. These two results indicate that effect of loading history can be neglected in evaluating tensile behavior of surface unliquefied soil.Load acting on the structure during the liquefaction-induced flow is evaluated numerically considering the three dimensional behavior. This force is compared with the horizontal force that is considered in the conventional design such as inertia force. A case study is made using the soil profile at Port Island where significant liquefaction-induced flow occurred. The calculation is made with the size of the structure as parameter. It is found that horizontal force considered in the conventional design is larger that the force caused by liquefaction-induced flow if the cross-sectional shape is dose to square, but the latter becomes larger when width-depth ratio increase& It indicates that remedial measure against liquefaction-induced flow must be re-considered.