摘要
在第四系浅层气分布区,含气土地基的固结沉降易引发建筑物不均匀沉降、结构物开裂甚至倾覆等工程危害。为探求含气软土的固结变形与微结构演化特性,对珠江口海相重塑含气软土进行室内一维固结试验和微结构扫描电镜(SEM)试验,采用Image-Pro Plus(IPP)软件对蠕变前后的SEM图像进行处理,提取能描述微观结构特征的相关参数(孔隙度、孔隙圆度、孔隙分形维数、孔径大小、孔隙定向性特征等),定性定量分析含气软土微观结构的变化规律。结果表明,相较于饱和软土,含气软土的沉降变形更为显著,并且随着初始含气量的增加,沉降变形逐步增大。当考虑水孔隙比时,含气软土的压缩曲线和饱和软土基本重合。固结后土样大孔隙(40~50μm)和大孔穴(500~1000μm)减小,中孔隙(1.5~10μm)和小孔穴(50~300μm)数量增加、形状趋向扁平状发展、定向性变化不明显,孔隙特征的渐变过程揭示了含气软土固结变形的微观机制。
In areas with shallow Quaternary gas-bearing strata,the consolidation settlement of gassy soil foundations can lead to engineering hazards such as differential building settlement,structural cracking,and even overturning.To investigate the consolidation deformation and microstructural evolution characteristics of gassy soft clay,a series of laboratory one-dimensional consolidation tests and scanning electron microscopy(SEM)tests were conducted on marine remolded gassy soft clay from the Pearl River Estuary.The SEM images before and after creep were processed using Image-Pro Plus(IPP)software to extract microstructural parameters(e.g.,porosity,pore roundness,pore fractal dimension,pore size,and pore orientation characteristics)for qualitative and quantitative analysis of microstructural changes.The results show that,compared to saturated soft clay,gassy soft clay exhibits more pronounced settlement deformation,which increases with higher initial gas content.When the water void ratio is considered,the compression curves of gassy and saturated soft clay essentially coincide.After consolidation,large pores(40~50μm)and macrovoids(500~1000μm)decrease,while medium pores(1.5~10μm)and small voids(50~300μm)increase in number and tend to flatten,with no significant change in orientation.This gradual evolution of pore characteristics reveals the microscopic mechanism behind the consolidation deformation of gassy soft clay.
作者
周千惠
王凌
袁柱
王典
赵广辉
郭清锋
常留成
ZHOU Qianhui;WANG Ling;YUAN Zhu;WANG Dian;ZHAO Guanghui;GUO Qingfeng;CHANG Liucheng(Guangzhou Metro Design&Research Institute Co.Ltd.,Guangzhou,Guangdong 510410;Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071)
出处
《地质与勘探》
北大核心
2025年第4期841-850,共10页
Geology and Exploration
基金
国家自然科学基金重大仪器专项(编号:52127815)资助。
关键词
含气软土
固结变形
微结构
扫描电镜
水孔隙比
gassy soft clay
consolidation deformation
microstructure
scanning electron microscope(SEM)
water void ratio
