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

由于1995年兵库县南部地震（坂神淡路地震灾害），科比港口岛的含砾石的Masado土壤被极度液化，这被认为比干净的沙子更难液化。本研究是Masado土液化特性的实验研究结果。首先，对取自科比港口岛的重塑土样和原状土样进行了不排水单调压缩和拉伸试验。对于重建土样，本研究使用了两种不同等级的Masado土，并采用了两种不同的土样制备方法。在对重塑土样的系列试验中，发现了以下实验结果：在稳定状态下的应力状态信息是相同的，与试样的制备方法和围压无关，土样的孔隙比是相同的。稳态包络线的倾角 关于我们 压缩和拉伸载荷不同，相应地，在压缩和拉伸载荷的稳定状态下的偏应力也不同。在相变状态下，水沉法制备的土样所获得的平均有效应力低于湿沉法制备的土样。在对原状土样的系列试验中，发现原状土样主要表现为剪胀特性。原状土样的孔隙比与平均有效应力之间的关系表现出很大的分散性，这可能是由于土样的级配变化引起的。然后，安装了大型三轴试验装置，该装置可以对土样施加等幅运动和随机地震运动，并进行了一系列的试验。首先，对致密丰浦砂进行了不排水循环试验，并将试验结果与现有已发表的试验结果进行了验证。然后，在1995年兵库县南部地震时记录的地震运动的不排水试验进行了密集丰浦砂，和强烈的运动，即的特性的影响。脉冲型或振动型。最后，对Masado土进行了等幅和地震作用下的不排水试验，结果表明，Masado土的液化强度在较低的循环次数下低于致密丰浦砂，地震作用对Masado土的液化影响较小。少

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