LIQUEFACTION RESISTANCES OF UNSATURATED NON-PLASTIC SILT
LIQUEFACTION RESISTANCES OF UNSATURATED NON-PLASTIC SILT
复制标题
DOI：
10.3208/sandf.49.221
复制
发表时间：
2009-04
影响因子：
3.7
通讯作者：
M. Okamura;Kohei Noguchi
中科院分区：
文献类型：
--
作者：
M. Okamura;Kohei Noguchi
研究表明，提高非饱和砂土抗液化强度的机理可能有两种。第一种机制是部分饱和砂体中的空气通过减少其体积来吸收产生的超孔隙压力。Okamura和Soga（2005）从理论上推导出部分饱和砂土抗液化强度的影响因素，并通过一系列干净砂土的三轴试验来检验这些因素的影响。他们发现了抗液化比与潜在体积应变之间的独特关系，这使得可以估计部分饱和砂土的抗液化性。第二种是非饱和砂的基质吸力，它增加了有效应力，从而提高了土体的强度。本研究针对非塑性粉土进行了两组动三轴试验，以观察两种液化机制下的抗液化强度。在第一个系列中，一个顶帽与蓄液罐被用来研究孔隙流体的压缩性对抗液化的影响。Okamura和Soga推导的经验关系式被发现是有效的，即使对于粉土，假设基质吸力可以忽略不计。在第二个测试系列中，使用了普通帽。抗液化强度随基质吸力的增加而线性增加，其增加率大于净应力的增加率。归一化抗液化强度与基质吸力之间存在唯一的线性关系。结果总结的形式，可以很容易地应用于评估部分饱和土的抗液化性。
It has been pointed out that there are two possible mechanisms that enhance liquefaction resistances of unsaturated sand. The first mechanism is where air in a partially saturated sand mass plays a role of absorbing generated excess pore pressures by reducing its volume. Okamura and Soga (2005) derived the influential factors of the liquefaction resistance for partially saturated sand from theoretical consideration and effects of the factors were examined through a series of triaxial tests on a clean sand. They found a unique relationship between liquefaction resistance ratios and the potential volumetric strain, which allows the estimation of the liquefaction resistance for partially saturated sand. The second is the matric suction of unsaturated sand which increases the effective stress and thus the strength of the soil mass. In this study two series of cyclic triaxial tests on non-plastic silt were carried out to observe the liquefaction resistance in both mechanisms. In the first series, a top cap with an accumulator tank was used to study the effect of compressibility of pore fluid on the liquefaction resistance. The empirical relationship derived by Okamura and Soga is found to be valid even for the silt provided that the matric suction is negligible. In the second test series an ordinary cap was used. The liquefaction resistance increased linearly with the matric suction, with the increasing ratio being higher than that for the net stress. A unique linear relationship is found between the normalized liquefaction resistance and the matric suction. Results are summarized in the form which can be easily applied to evaluate the liquefaction resistance of a partially saturated soil.