基于固结与回弹试验的黄土自重湿陷下限深度确定方法  

Determination Method of Lower Limit Depth of Loess Self⁃weight Collapse Based on Consolidation and Rebound Test

作　　者：井彦林[1] 冯雅茜 何椿霖 赵宏宇 乔泽 张旭彬 JING Yanlin;FENG Yaxi;HE Chunlin;ZHAO Hongyu;QIAO Ze;ZHANG Xubin(School of Civil Engineering,Chang’an University,Xi’an 710061,China)

机构地区：[1]长安大学建筑工程学院,西安710061

出　　处：《铁道建筑》2023年第2期116-122,共7页Railway Engineering

基　　金：国家自然科学基金(41472267)。

摘　　要：针对室内湿陷试验判定的黄土自重湿陷性与现场试坑浸水试验结果差异较大的问题,本文以西安黄土为研究对象,进行了黄土的自重湿陷系数试验与回弹试验,结果显示卸荷回弹变形与自重湿陷变形间存在紧密联系。通过扫描电镜试验、压汞试验等分析了不同压力下回弹变形与黄土微结构间的关系。应力较小时回弹变形较大,浸水附加变形(湿陷变形)以弹性为主并在卸荷后完全恢复,土体结构保持稳定;应力较大时回弹变形极小,浸水附加变形在卸荷后无法恢复,土体结构明显破损,黄土发生湿陷。在理论分析与试验结果的基础上提出了一种判定黄土自重湿陷下限深度的方法。黄土自重湿陷系数试验后,若土样卸荷回弹稳定高度大于浸水前固结稳定高度,则黄土不具自重湿陷性,反之则具有自重湿陷性,具有自重湿陷性的最大土层深度即自重湿陷下限深度。经工程实例验证,本文方法的判定结果与现场试坑浸水试验结果一致。In view of the large difference between the self-weight collapsibility of loess determined by the indoor collapsibility test and the results of the in-situ pit immersion test,the self-weight collapsibility coefficient test and rebound test of loess have been carried out with Xi’an loess as the research object.The results show that there is a close relationship between the unloading rebound deformation and the self-weight collapsibility deformation.The relationship between the rebound deformation and the microstructure of loess under different pressures was analyzed by scanning electron microscope test and mercury intrusion test.When the stress is small,the rebound deformation is large,and the additional deformation(collapsible deformation)after immersion is mainly elastic and completely recovered after unloading,and the soil structure remains stable.When the stress is large,the rebound deformation is very small,the additional deformation after immersion cannot be recovered after unloading,the soil structure is obviously damaged,and the loess collapses.On the basis of theoretical analysis and experimental results,a method to determine the lower limit depth of loess self-weight collapse is proposed.After the loess self-weight collapsibility coefficient test,if the unloading rebound stability height of the soil sample is greater than the consolidation stability height before immersion,the loess does not have self-weight collapsibility,otherwise it has self-weight collapsibility.The maximum depth of the soil layer with self-weight collapsibility is the lower limit depth of self-weight collapsibility.The results of the method in this paper are consistent with the results of the in-situ pit immersion test.

关 键 词：铁路路基 自重湿陷下限深度 试验研究 黄土 卸荷回弹 

分 类 号：TU444[建筑科学—岩土工程]