湿陷性黄土卸荷试验及其微结构  

Unloading Test of Wet Sinking Loess and Its Microstructure

作　　者：刘昌旺 郅彬[1] 任毅龙 LIU Chang-wang;ZHI Bin;REN Yi-long(School of Architecture and Civil Engineering,Xi'an University of Science and Technology,Xi'an 710054,China)

机构地区：[1]西安科技大学建筑与土木工程学院,西安710054

出　　处：《科学技术与工程》2024年第27期11826-11833,共8页Science Technology and Engineering

基　　金：陕西省西安市岩土与地下工程重点实验室项目(2060521002)。

摘　　要：湿陷性黄土在卸荷状态下的湿陷量与恒压下不同,通过试验从宏观与微观角度研究了卸荷作用下黄土湿陷量与微观结构变化情况。对铜川地区黄土进行湿陷性试验,测得不同埋深处恒压与卸荷的湿陷性系数,对比恒压与卸荷、湿陷系数的差异性,并结合电镜扫描(scanning electron microscope,SEM)与图像分析系统PCAS(particles and cracks analysis system)观测分析湿陷性黄土微观结构变化,得到不同埋深、卸荷量下微观参数孔隙面积占比、概率熵与平均形状系数等变化特征。结果表明:卸荷将有效提高湿陷起始压力,减少湿陷性的发生,相较于恒压条件下改变了湿陷性黄土孔隙面积、颗粒分布、排列方式等;微观结构主要以片状和蜂窝结构为主,随埋深与卸荷量增加,孔隙由疏到密、细小孔隙占比增加;概率熵逐渐增大、颗粒排列混乱且定向性变差,均一化程度降低;卸荷作用下黄土的湿陷系数、埋深与卸荷量有很强的相关性。The changes of wetting and microstructure of loess under unloading from macroscopic and microscopic viewpoints was investigated.The wet subsidence test was conducted on the loess in Tongchuan area,and the wet subsidence coefficients of constant pressure and unloading were measured at different burial depths,and the differences between constant pressure and unloading and wet subsidence coefficients were compared,and the microstructural changes of wet subsided loess were analyzed by combining SEM(scanning electron microscope)and PCAS(particles and cracks analysis system)observations,and the characteristics of changes in microscopic parameters such as pore area percentage,probability entropy and average shape coefficient were obtained at different burial depths and unloading.The results show these as follows.Unloading will effectively increase the initial pressure of wet sink and reduce the occurrence of wet sink,and change the pore area,particle distribution and arrangement of wet sink loess compared with the constant pressure condition;the microstructure is mainly lamellar and honeycomb structure,with the increase of burial depth and unloading amount,the pore space increases from sparse to dense,and the percentage of fine pore space increases;the probability entropy gradually increases,the particle arrangement becomes chaotic and poorly oriented,and the degree of homogenization.There is a strong correlation between the wetting coefficient,burial depth and unloading volume of loess under the unloading effect.

关 键 词：湿陷性黄土 卸荷 湿陷系数 微结构 

分 类 号：TU444[建筑科学—岩土工程]