上覆荷载作用下钦州海积软土孔隙结构特征变化  

Pore structure changes for marine soft soil under overlying loadings

作　　者：周东[1,2] 焦文灿 吴恒[1,2] 刘汉民[1,2] 王业田[1,2] ZHOU Dong JIAO Wen-can WU Heng LIU Han-min WANG Ye-tian(a. College of Civil Engineering and Architectur b. Key Laboratory of Disaster Prevention and Structural Safety of the Ministry of Education, Guangxi University, Nanning 530004, Chin)

机构地区：[1]广西大学土木建筑工程学院,南宁530004 [2]广西大学工程防灾与结构安全教育部重点实验室,南宁530004

出　　处：《桂林理工大学学报》2017年第1期81-87,共7页Journal of Guilin University of Technology

基　　金：国家自然科学基金项目(51178124);广西科技计划重点项目(桂科攻0895004-2;0992027-3)

摘　　要：粘土孔隙结构特征对土体的水理性质和力学性状尤为重要。为探讨海相软粘土结构强度增长过程中孔隙的演化机制,以广西北部湾钦州地区海相软土为研究对象,通过对不同上覆荷载作用下的土样进行压汞仪法(MIP)试验和扫描电镜图像(SEM)分析,揭示土样孔隙特征(尺度分布、平均孔径、孔隙体积密度和临界孔径)随上覆荷载的变化规律,以及其与土体渗透性、结构强度之间的联系。试验结果表明:上覆荷载作用下,土样孔隙呈大孔隙(>10μm)—中孔隙(1~10μm)—小孔隙(0.1~1μm)—微孔隙(<0.1μm)的演化趋势,大、中孔隙逐渐分裂和湮灭成小、微孔隙,但并非均是优先调整大孔隙来补偿小、微孔隙;平均孔径和临界孔径能直接反映孔隙结构特征的重分布和结构性演化,随着平均孔径的逐渐减小,土样的渗透性逐渐降低、结构强度逐渐增强;通过SEM图像分析,粘土结构演化过程呈蜂窝状结构—紊流状结构—粒状堆叠结构—胶粘式结构的发展趋势。The change of pore structure characteristics of soil is important in water-physical properties and me-chanical behavior. Marine soft soil obtained from Beibu Gulf of Guangxi is used as research object to discuss the evolution mechanism of pore during the growth process of clay structure. MIP tests and SEM image analysis were conducted with different overlying loadings, to reveal the variation law of pore scale distribution, average pore diameters, pore volume density and critical pore size of soil. The study reveals the connection between these four factors and the permeability, structural strength of soil. The soil specimens evolution trends are macro pores（ 〉 10 [xm） to middle pores（ 1 - 10 （xm） to small pores（0？ 1 - 1 （xm） then to micro pores（〈0？ 1 （xm） ？ Macro and middle pores split gradually into small and micro pores, but not all macro pores are preferably adjusted to com-pensate for small, micro pores. The average pore size and the critical pore size directly reflect the redistribution of pore structure characteristics and structural growth. With gradual decrease of average pore size, the permea-bility of soil decreases while structural strength grows, which occurs in “binding pore” in soil. This kind of pore has high sensitivity to soil cohesion. Based on the analysis of SEM images, the clay-structure growth process presents the trends from cellular structure to turbulent structure to granular stacking structure then to cohesive structure.

关 键 词：孔隙尺度分布 平均孔径 临界孔径 结构强度 渗透性 

分 类 号：TU411.92[建筑科学—岩土工程]