Static And Dynamic Characteristics Of Intact Loess And Its Structure Under Different Water Content

This paper deals with the problem of quantitative parameter expressing the characteristics of soil structure so-called as"the focus problem of soil mechanics in the 21# century". Loess is a kind of typical structural soil, its special structure and special sensitivity to water effect on the characteristics of engineering mechanics of loess, this is also the special aspect of the study on static and dynamic behavior of loess. In this paper, based on the observation and analysis of a large number of literature references about the static and dynamic behavior and structure characteristics, from the works in this paper, some outcomes are obtained as following:On basis of a new soil mechanical method, load is applied on disturbed saturated loess samples which have the same dry density in order to destroy structure of intact loess. By means of compression, drained tri-axial and dynamic test under different water content, a soil structure parameter was put forward with under compression, static and dynamic stress condition, variation characteristics were studied under different stress condition, and the correlation factors influencing the loess structure are analyzed, it indicates structure parameter has rationality and sensitivity as well as stability. The relationship between static and dynamic characteristics were studied, the structural constitutive relations of intact loess are put forward for static and dynamic stress conditions.The quantitative comprehensive structural parameter based on deformation is defined by using void ratio of intact and disturbed as well as saturated loess under compression stress condition. compressibility, collapsibility and moistening collapsibility were interpreted by means of the parameter, relationship curve between structural parameter and coefficient of collapsibility, moistening coefficient of collapsibility were the same line, the tests of parameters of Xi'an, Lanzhou, Qinghai, Yangling intact loess and Xi'an compacted loess about line relationship were the same under different pressure and water content, it can calculate the collapsibility and moistening collapsibility deformation, it gets a further step on collapsibility research by means of structure parameter.The quantitative comprehensive structural parameter based on stress is defined by static and dynamic stress under the same strain of intact and disturbed as well as saturated loess under static and dynamic tri-axial stress condition, it can reveal water content and consolidation stress influencing factors to the static and dynamic characteristics. The relationship curves between structural parameter variation quantity and static and dynamic strain are hyperbola, structural parameter expression can be obtained under static and dynamic stress condition, the expression add to static and dynamic stress strain relation of disturbed saturatedloess, the structural constitutive relations of intact loess are put forward for static and dynamic stress conditions. The structural constitutive relations considered factors of moistening and load to loess structure, and it has the same parameter of Duncan-Chang and Hardin model, the results of comparison between predicted and observed dynamic stress-strain curves of intact loess inosculate better.