扰动程度对湛江组结构性黏土触变性的影响

Effect of Disturbance Degree on Thixotropy of Structural Clay in Zhanjiang Formation

扰动对湛江组结构性黏土触变性具有重要影响,扰动程度不同,湛江组结构性黏土触变强度恢复程度也不同。为探究扰动程度对湛江组结构性黏土触变性的影响规律,对该土展开室内模型试验研究。基于现场原位十字板剪切试验,设计模型装置,采用室内振动试验模拟土样受扰过程,在不同扰动程度(0、33%、66%、100%)、不同静置时间(0、7、28、56、91 d)下对3种土样进行微型十字板剪切试验,在相同扰动程度(66%)、不同静置时间(0、7、28、56、91 d)下对3种土样进行无侧限抗压强度试验,分别测试各静置时间下的微型十字板不排水抗剪强度和无侧限抗压强度,分析扰动程度对土体触变恢复强度的影响规律。结果表明:土体扰动时间与扰动程度正相关。在相同扰动程度下,强度恢复程度、触变恢复强度比均随静置时间的增加而增大,触变灵敏度随静置时间的增加而降低;土体结构性越强,强度恢复程度、触变恢复强度比随静置时间增加而增大的幅度和速率越大,触变灵敏度随静置时间增加而降低的幅度和速率越大。在不同扰动程度下,强度恢复程度与扰动程度呈线性关系,触变恢复强度比与扰动程度呈反比例关系。

The thixotropy of structural clay in Zhanjiang Formation is affected by disturbance,the recovery degree of thixotropy strength of structural clay in Zhanjiang Formation varies with the degree of disturbance.In order to explore the influence of disturbance degree on thixotropy of structural clay in Zhanjiang Formation,a model test was carried out in the laboratory.Based on the in-situ shear test of cross plate,the model device was designed,indoor vibration test was used to simulate the disturbed process of soil samples.The micro-cross plate shear test was carried out on three kinds of soil samples under different disturbance degree(0,33%,66%,100%)and different standing time(0,7,28,56,91 d).Under the same disturbance degree(66%)and different standing time(0,7,28,56,91 d),the unconfined compressive strength tests of the three soil samples were carried out,the undrained shear strength and unconfined compressive strength of the micro-cross plate at each standing time were tested respectively,the influence law of disturbance degree on thixotropic recovery strength of soil was analyzed.The results show that the disturbance time of soil is positively correlated with the disturbance degree.For the same degree of disturbance,the strength recovery degree and thixotropic recovery intensity ratio increased with the increase of standing time,and the thixotropic sensitivity decreases with the increase of standing time.The stronger the soil structure,the greater the amplitude and rate of strength recovery and thixotropic recovery strength ratio increases with the increase of standing time,and the greater the amplitude and rate of thixotropic sensitivity decreases with the increase of standing time.Under the different degree of disturbance,there is a linear relationship between strength recovery degree and disturbance degree,and an inversely proportional relationship between thixotropic recovery intensity ratio and disturbance degree.