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

得到了土体块体在拉伸加载条件下液化诱导流动过程中地表未液化土的特性。采用空心扭剪试验装置进行了新鲜试验和阶段试验。结果表明，在循环荷载作用下，其抗拉强度约为抗压强度的1110。另外，在小菌种下，鲜试与阶段试有一定差异，但在大菌种下，鲜试与阶段试无差异。这两个结果表明，在评价地表非液化土的拉伸性能时，加载历史的影响可以忽略不计。考虑液化诱导流动的三维特性，对作用在结构上的载荷进行了数值计算。将此力与传统设计中考虑的水平力（如惯性力）进行比较。以港岛的土壤剖面为例进行了研究，在那里发生了显著的液化引起的流动。以结构尺寸为参数进行计算。研究发现，常规设计中考虑的水平力比截面形状为方形时液化诱导流产生的力大，但随着宽深比的增大，液化诱导流产生的力变大，必须重新考虑液化诱导流的补救措施。

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.