南阳膨胀土浸水变形特性及微观结构研究  

Investigation of swelling behavior and microstructure of expansive clay in Nanyang area

作　　者：范文晓 Fan Wenxiao(School of Civil Engineering,Xinjiang Institute of Engineering,Urumqi 830023,China)

机构地区：[1]新疆工程学院土木工程学院,新疆乌鲁木齐830023

出　　处：《建筑科学》2025年第1期126-135,共10页Building Science

基　　金：新疆维吾尔自治区高校基本科研业务费科研项目(XJEDU2024P082);国家自然科学基金项目(42462030)。

摘　　要：为探究南阳地区膨胀土变形时程特性,首先测定了土-水特征曲线,开展了一系列不同饱和度和上覆应力的一维膨胀试验,阐明了其膨胀变形特性并提出了双曲线模型,结合压汞试验探究了南阳膨胀土浸水变形过程中的微观结构演变规律。结果表明:膨胀变形时程曲线为“S”型,变形展现三阶段时程特性。第一阶段为初始膨胀,膨胀变形发展并不显著。第二阶段为主要变形阶段,试样膨胀变形迅速增加。第三阶段为膨胀稳定阶段,膨胀变形增长非常缓慢,已基本处于稳定状态。变形时程曲线可用双曲线形式表述。在双曲线模型中,初始膨胀速率和最终膨胀变形控制曲线形状和位置。最终膨胀变形与初始吸力和上覆应力呈三维对数曲面,初始膨胀速率随最终膨胀变形增加呈指数增加。非饱和时试样呈双峰结构,浸水膨胀后,从双峰布变成单峰分布,施加上覆压力主要导致1μm~10μm孔隙压缩。SEM照片显示,非饱和状态下,试样团聚体多呈鳞状,粒径较大,颗粒间接触较强。浸水后,由于试样团聚体呈絮凝状,粒径较小,粒间接触减弱。试样浸水前后宏观变形和孔径分布的改变主要由团聚体膨胀导致。To explore the deformation time-history characteristics of expansive soil in Nanyang area,the soil water characteristic curve is first measured,and a series of one-dimensional expansion tests with different saturation and overlying stress are carried out to elucidate its expansion deformation characteristics.A hyperbolic model is proposed,and the microstructure evolution law of Nanyang expansive soil during immersion deformation is explored through MIP experiments.The results show that the expansion deformation time history curve is an “S” shape,and the deformation exhibits three-stage time history characteristics.The first stage is initial expansion,and the development of expansion deformation is not significant.The second stage is the main deformation stage,and the expansion deformation of the sample increases rapidly.The third stage is the stable expansion stage,where the expansion deformation grows very slowly and is basically in a stable state.The deformation time-history curve can be expressed in hyperbolic form.In the hyperbolic model,the initial expansion rate and final expansion deformation control curve shape and position.The final expansion deformation follows a three-dimensional logarithmic curve with initial suction and overlying stress,and the initial expansion rate increases exponentially with the increase of final expansion deformation.When the sample is unsaturated,it exhibits a bimodal structure and expands after immersion in water,changing from a bimodal distribution to a unimodal distribution.The application of overlying pressure mainly leads to 1μm~10μm pore compression.SEM photos show that under unsaturated conditions,the agglomerates in the sample are mostly scaly,with larger particle sizes and stronger interparticle contact.After immersion,due to the agglomerates of the sample being flocculent and having a smaller particle size,the contact between particles is weakened.The changes in macroscopic deformation and pore size distribution of the sample before and after immersion are mainl

关 键 词：膨胀土 变形时程 一维膨胀 双曲线模型 

分 类 号：TU443[建筑科学—岩土工程]