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LIQUEFACTION STRENGTH CHARACTERISTICS OF GARAVEL-CONTAINING SANDY SOILS UNDER LOWER NUMBERS OF CYCLES AND ELEVATED CONFINING PRESSURE

低循环次数、高围压下含砾砂土的液化强度特征

基本信息

批准号：
08405035
负责人：
ISHIHARA Kenji
金额：
$ 19.01万
依托单位：
Tokyo University of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08405035/
关键词：
CYCLIC STRENGTH OF SOILS EARTHQUAKE MOTION LIQUEFACTION CYCLIC TRIAXIAL TEST

项目摘要

Due to 1995 Hyogo-ken Nambu Earthquake (Hanshin-Awaji Earthquake Disaster), gravel-containing Masado soils at Kobe Port Island were extremely liquefied, which were considered to be less liquefiable than clean sand. This study shows the outcome of experimental investigations on liquefaction characteristics of Masado soils.First, undrained monotonic compression as well as extension tests were carried out on reconstituted soil samples and intact soil samples recovered from Kobe Port Island. For reconstituted soil samples two different Masado soils having different gradations were used, and two different preparation methods of soil samples ***e adopted in this study. In the test series on reconstituted soil samples, the following experimental findings were found. Stress states at steady states of information are the same independent of sample preparation methods and confining pressures, in the void ratios of the soil samples are the same. The inclinations of the steady state envelopes for … More compressive and extensional loadings differ, accordingly, the deviator stresses at steady states for compressive and extensional loading are different. At states of phase transformation, mean effective stress achieved by the soil samples prepared by water sedimentation are lower those prepared by wet tamping. In the test series on intact soil samples, it was found that the intact soil samples shows mainly dilative behavior. The relationship between void ratios and mean effective stresses for the intact soil samples shows much scatter, probably due to a variation in gradations of the soil samples.Then, large-scale triaxial test apparatus with a hydraulic actuator, which enables constant amplitude motions as well as random earthquake motions to be applied to soil samples, were installed, and a series of experiments were carried out. First, undrained cyclic tests were performed on dense Toyoura sand, and the test results were verified against the existing published test results. Then, undrained tests subject to the earthquake motions, which were recorded at the time of 1995 Hyogo-ken Nambu Earthquake, were performed on dense Toyoura sand, and the influence of the characteristics of strong motions, I e. impulse-type or vibration-type, was examined. Finally, undrained tests under constant-amplitude and earthquake motions were performed on Masado soils, and it was found that liquefaction strengths of Masado soils are lower than those of dense Toyoura sand at lower number of cycles, and the characteristics of earthquake motions have less influence on the liquefaction of Masado soils. Less

由于1995年兵库县南部地震（阪神淡路地震灾害），神户港岛含有砾石的Masado土壤极度液化，被认为比干净的沙子更难液化。本研究展示了Masado土液化特性的实验研究结果。首先，对从神户港岛回收的重构土样和完整土样进行了不排水单调压缩和延伸试验。对于重构土壤样品，使用了两种具有不同级配的不同 Masado 土壤，并在本研究中采用了两种不同的土壤样品制备方法。在对重建土壤样品的系列测试中，发现了以下实验结果。信息稳态下的应力状态是相同的，与样品制备方法和围压无关，土样的孔隙比是相同的。压缩和拉伸载荷的稳态包络线的倾角不同，相应地，压缩和拉伸载荷稳态下的偏应力也不同。在相变状态下，通过水沉降制备的土样所达到的平均有效应力低于通过湿捣实制备的土样。在对完整土样的系列测试中，发现完整土样主要表现出膨胀行为。完整土样的孔隙率和平均有效应力之间的关系表现出很大的分散性，这可能是由于土样级配的变化所致。然后，安装了带有液压驱动器的大型三轴试验装置，该装置能够对土样施加恒定振幅运动以及随机地震运动，并进行了一系列实验。首先，在致密的丰浦砂上进行了不排水循环试验，并将试验结果与现有公布的试验结果进行了验证。然后，针对1995年兵库县南部地震时记录的地震运动，在致密的丰浦砂上进行了不排水试验，并研究了强运动特性的影响。脉冲型或振动型进行了检查。最后，对马萨多土进行了等幅和地震作用下的不排水试验，发现在较低的循环次数下，马萨多土的液化强度低于致密丰浦砂，且地震运动特性对马萨多土的液化影响较小。较少的