A study on the liquefaction of gravely soils such as Masa

采用室内试验和文献调研相结合的方法，研究了1995年日本南部大地震和1931年日本崎玉大地震两次大地震后液化重质土的土壤状况。在Hyogoken-Nambu地震中，神户市及其周边的许多填海土地上，一种名为Masa的严重沙子被液化。通过循环三轴试验对原状土样的液化强度进行了研究。在此基础上，研究了两种不同影响因素对玛莎砂土液化强度的影响，即饱和度和地层交替度。在第一个效应中，通过不排水循环三轴试验验证了饱和土样和部分饱和土样液化强度的差异。试验结果表明，液化强度随饱和比的减小而增大。在第二次试验中，制备了两种类型的样品，即均匀混合的颗粒和将颗粒分选成三种粒度的样品。试验结果表明，两种试件的液化强度没有差异。1931年西崎玉地震的土壤调查数据和破坏报告都是收集的。在此基础上，对液化场地的土壤条件进行了评价。液化场地主要为老河道和天然大堤。在一些液化场地发现了严重的土层。

Soil conditions of liquefied gravely soils by two earthquakes, 1995 Hyogoken-nambu earthquake and the 1931 Nishi-saitama earthquake was studied by several laboratory tests and literature surveys. In the Hyogoken-nambu earthquake, a gravely sand named Masa was liquefied at many reclaimed lands in and around Kobe City. Liquefaction strength of undisturbed samples was studied at first by cyclic triaxial tests. Then two kinds of efrects on the liquefaction strength of Masa, saturation ratio and alternation of strata were studied. In the first effect, undrained cyclic triaxial tests were carried out to demonstrate the difference of liquefaction strength between saturated and partial saturated samples. Test results showed that liquefaction strength increased with the decrease of saturation ratio. In the second tests, two types of samples, mixed of grains uniformly and sorted of grains into three grain sizes, were prepared. Test results showed that liquefaction strength of two types of samples had no difference.Soil investigation data and reports on the damage were collected for the 1931 Nishi-saitama earthquake. Based on these data, soil condition of liquefied sites were evaluated. Liquefied sites were mainly old river channel and natural levee. Gravely soil layrs were found at some liquefied sites.