不同先期固结压力下重塑软黏土微观结构研究  

A Microstructural Study of Remodeled Soft Clay Under Different Prior Consolidation Pressures

作　　者：彭俊发 刘红军[1] 杨超 PENG Jun-fa;LIU Hong-Jun;YANG Chao(School of Civil Engineering and Architecture,Wuyi University,Jiangmen 529020,China)

机构地区：[1]五邑大学土木建筑学院,广东江门529020

出　　处：《五邑大学学报（自然科学版）》2024年第2期72-78,共7页Journal of Wuyi University(Natural Science Edition)

基　　金：广东省教育厅广东省普通高校特色创新项目(2020KTSCX152);五邑大学教学质量工程与教学改革工程项目(JX2021023);五邑大学博士科研启动基金项目(5041700131);五邑大学学生创新创业项目(2020CX10)。

摘　　要：为了研究软黏土在不同先期固结压力下的微观结构特征,将珠三角西部地区软黏土重塑为5组土样,1组不施加荷载,第2至5组分别施加50、100、200、300kPa的轴向压力,经过24h后再统一卸载到50kPa,待土体变形稳定后选取有代表性的部位进行扫描电镜试验.利用PCAS软件对土样的微观结构进行定性和定量分析,研究结果显示,重塑软黏土的微观结构主要呈密集基质状和蜂窝状的微结构,颗粒之间多为点与面、面与面纤维状胶结接触,单元体之间有镶嵌和架空结构;随着先期固结压力的增加,1号到5号土样微观结构的变化为:表观孔隙率从46.3%降到40.0%,孔隙体积变小;平均形状系数从0.325减小到0.238,土样孔隙形状逐渐变得狭长;概率熵从0.992减小到0.975,孔隙排列更统一,有序性增强;分形维数从1.443下降至1.308,黏性土微观结构复杂程度降低.In order to study the microstructural characteristics of soft clay under different prior consolidation pressures,the soft clay in the western part of the PRD region was remolded into five groups of soil samples,with no load applied to group 1,and axial pressures of 50,100,200,and 300 kPa were applied to groups 2 to 5,respectively,which were then uniformly unloaded to 50 kPa after 24 h.Representative parts of the soils were selected for scanning electron microscopy(SEM)tests when the deformation of the soil body was stabilized.Then the microstructure of the soil samples was analyzed qualitatively and quantitatively using PCAS software,and the results of the study showed that the microstructure of the remodeled soft clay was mainly a dense matrix-like microstructure and honeycomb microstructure,with mostly point-to-point and surface-to-surface fibrous cementation contacts between particles,and mosaic and shelf structures between the units;with the increase of the prior consolidation pressure,the microstructure of the soil samples from No. 1 to No. 5 changed as follows: apparent porosity decreased from 46.3% to 40%, and the pore volume became smaller;the average shape coefficient decreased from 0.325 to 0.238, and the pore shape of soil samples gradually became narrow;the probability entropy decreased from 0.992 to 0.975, the pore arrangement was more uniform, and the ordering was enhanced;the fractal dimension decreased from 1.443 to 1.308, and the complexity of the microstructure of the clayey soil decreased.

关 键 词：先期固结压力 重塑软黏土 扫描电镜 压缩试验 定量分析 

分 类 号：TU472[建筑科学—结构工程]