粉土动力特性研究综述

Review of Silty Soil Dynamic Characteristics

粉土是一种具有特殊工程性质的土,粉土中砂粒、粉粒、粘粒都存在,这3种粒种分别具有不同的性质。总结这3种粒种对粉土动模量和阻尼的影响,得到了粉土模量阻尼的表达式以及粉土动力特性符合土体非线性和滞后性的一般规律。液化是一种特殊的强度问题,国内外预测液化可能性的方法主要有经验法、剪切波速法、Seed法、有限元法等。室内研究主要集中在粉土动力特性试验研究上,研究了各种因素影响下粉土液化特性,包括3种不同的粒种对粉土液化特性的影响,尤其是粘粒含量影响下粉土液化特性。粉土的动孔压响应与砂土有很大区别,这也可以用粉土特殊的颗粒结构组成来分析。最后,分析了粉土液化机理,并对粉土进一步研究提出了几点看法。

Much destruction would be caused by vibration in various natural disasters. The dynamic characteristic of sand, especially liquefaction characteristic, has been studied for a long time, while in comparison the history of the study of dynamic characteristic of silty soil is relatively short. Liquefaction is known to be caused by earthquake shaking, with the state of soil changing from solid to liquid. Silty soil is one of the engineering soils in nature of special interest, with distinct characteristics from those of sand. Silty soil has three kinds of properties, i.e., sand content, silt content and clay content, each of which has different dynamic characteristics including liquefaction characteristic. The influence is summarized of the three kinds of properties on dynamic modulus and dynamic damping. The functions of modulus and damping are also proposed. The tests have demonstrated that the dynamic characteristic of silty soil follows the general rule of non-linearity and hysteresis in soil. Liquefaction is a special issue related to the soil strength. The main methods for predicting the possibility of silt liquefaction are empirical method?SPT method?Seed method?FEM, and etc. The laboratory study is aiming at the determination of the dynamic characteristics through dynamic tests. The liquefaction characteristics of silty soils have been studied under various kinds of conditions. The influence of the clay content in silty soil is specially studied. The results of laboratory tests show that great differences exist between silty and sandy soil in response to pore water pressure. Finally, the mechanism of silt liquefaction is analyzed and the future studies about silt dynamic character are also suggested.