湛江组结构性黏土物理力学特性对其触变性的影响

INFLUENCE OF PHYSICO-MECHANICAL PARAMETERS OF STRUCTURAL CLAY IN ZHANJIANG GROUP ON ITS THIXOTROPY

广泛分布于北部湾沿岸地区的湛江组结构性黏土具有强烈的触变性,产生的工程问题比较突出。为了研究湛江组结构性黏土的物理力学特性对其触变性的影响,对湛江组结构性黏土触变性进行了一系列的宏观试验研究,通过改变含水率、孔隙比及灵敏度得到重塑土在不同静置龄期的触变强度比率,建立3种物理力学特性分别作为变量下重塑土的触变强度比率与静置龄期的关系,分析湛江组结构性黏土含水率、孔隙比及灵敏度对其触变性强弱的影响。结果表明:(1)湛江组结构性黏土扰动后,随着静置龄期的增加,含水率对湛江组结构性黏土触变强度影响较大,且含水率越大,湛江组结构性黏土触变强度增长的幅度越大;触变强度比率增长的速率表现为前期增长快,后期增长慢。(2)湛江组结构性黏土扰动后,在前期,孔隙比的变化对湛江组结构性黏土触变强度影响不显著,在后期,随着孔隙比增大,湛江组结构性黏土触变强度增长的速率与幅度显著减小。(3)湛江组结构性黏土强度恢复情况与灵敏度有关,湛江组结构性黏土扰动后,随着静置龄期的增加,不同灵敏度重塑土黏聚力、内摩擦角、触变强度比率均增大,扰动后,在静置前期,其黏聚力、内摩擦角、触变强度比率均增长快,扰动后,其黏聚力、内摩擦角、触变强度比率增长慢。

Widely distributed in the coastal areas of the Beibu Gulf,the structural clay of the Zhanjiang Group poses significant challenges to engineering practice due to its high thixotropy.To reveal the way that the factors of water content,void ratio and sensitivity can affect thixotropy,we conducted a series of tests examining how these physico-mechanical properties of the clay along with its thixotropy changed over time after disturbing the clay samples and putting them to stand.Test results show that:(1)higher water content leads to greater thixotropic strength growth by the end of the standing period,with the thixotropic strength growth rate being high in the early stage of standing and low in the late stage;(2)void ratio presents insignificant correlation with thixotropic strength growth during the early standing stage while,during the late stage,a higher void ratio is associated with considerably smaller growth in thixotropic strength as well as a lower growth rate;and(3)higher sensitivity leads to greater thixotropic strength.