考虑孔隙水盐分效应的人工软黏土工程特性与本构模型  

Engineering behavior and constitutive model of artificial soft clay considering pore water salinity effect

作　　者：张彤炜 邓永锋[2] 吴子龙[2] 刘松玉[2] 刘垚[2] ZHANG Tong-weil,;DENG Yong-feng;WU Zi-long;LIU Song-yu;LIU Yao(School of Civil Engineering and Mechanics,Department of Geotechnical Engineering,Key Laboratory of Mechanics on Disaster and Environment in Western China,Lanzhou University,Lanzhou 730000,China;Institute of Geotechnieal Engineering,Transportation College,Southeast University,Nanjing 210096,China)

机构地区：[1]兰州大学土木工程与力学学院地质工程系西部灾害与环境力学教育部重点试验室,甘肃兰州730000 [2]东南大学交通学院岩土工程研究所,江苏南京210096

出　　处：《岩土工程学报》2018年第9期1690-1697,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51378117,41572280,41807225,41790443);中央高校基本科研业务费专项资金项目(lzujbky-201-8);国家重点研发项目(2016YFC0800201)

摘　　要：中国江苏北部连云港地区海相软土蒙脱石族矿物含量相对较高,且在海陆交互环境沉积形成,沉积过程中具有孔隙水盐分较高的特点,但在后沉积过程中由于地表和地下淡水入侵,会使孔隙水盐分发生变化。工程设计一般依据既有地下水环境中土体参数,未能考虑盐分变化后土体参数变化,会造成工程安全系数的冗余度不足,进而导致工程风险。为了解决江苏北部地区基础设施运营中,孔隙水盐分变动环境下软黏土地基长期性状与工程性质变异问题,需要深入了解矿物成分、孔隙水盐分在软黏土物理和力学特性中的作用机制。由于天然软黏土的矿物成分、孔隙水成分差异较大,在黏土矿物盐敏性的研究和当地地下水盐分测试基础上,试验材料采用矿物成分均一的商用高岭土与膨润土组成的人工黏土作为研究对象,配制不同浓度的NaCl溶液作为孔隙水,模拟孔隙水盐分变化。通过液塑限试验、常规固结试验和固结不排水剪切试验,发现对于含蒙脱石矿物的人工黏土,液限w_L、压缩指数C_c和回弹指数C_s随着孔隙水盐分的增加而减小,而内摩擦角随着孔隙水盐分的增加而增加;对于高岭石矿物为主的人工黏土,液限w_L、压缩指数C_c、回弹指数C_s和内摩擦角都基本不随孔隙水盐分的增加而改变。将孔隙水盐分效应采用渗透吸力进行表征,在试验规律、修正剑桥模型和BBM模型认知的基础上,建立了考虑盐分效应的人工软黏土本构模型,并对比了计算结果与试验结果,两者在趋势上较为接近,验证了本构模型的实用性,可为近海岩土工程设计提供参考。The soft marine clay, which is deposited under the marine environment in the north plain of Jiangsu Province, is rich of montmorillonite mineral and saline pore water. During the post-sedimentary period, the soil suffers the invasion of the surface and underground freshwater, leading to the alteration and reduction of pore water salinity. Presently, the safety evaluation is generally based on the in-situ soil strength in the current environment. Hence, this non-consideration of the pore water salinity alteration may result in insufficient redundancy and potential risk. To clarify the evolution of the hydro-mechanical behavior of soils due to the alteration of pore water salinity during the operation of the coastal infrastructure, the impact of pore water salinity and clay mineral on the soil behavior is necessary to be investigated. To simplify the mineralogical influence, commercial kaolin and bentonite are selected. The physical and mechanical properties of artificial clay changing with pore water salinities（NaCl solution） are investigated using the Atterberg limits tests, oedometer tests and tri-axial tests. The results show that the liquid limits, compression index C_c and swelling index C_s of the artificial clay containing bentonite decrease with the pore water salinity, and its internal friction angle increases with the pore water salinity. Meanwhile, the liquid limits, compression index C_c, swelling index C_s and consolidated undrained strength of Kaolin are not affected by the pore water salinity. Finally, based on the testresults, modified Cambridge model and BBM model, an updated constitutive model considering pore water salinity effect represented by the osmotic suction is proposed, and the reliability is verified by the comparison between the calculated and measured data. These results will provide a reference for the design of coastal engineering.

关 键 词：人工软黏土 孔隙水盐分 矿物成分 工程特性 本构模型 

分 类 号：TU43[建筑科学—岩土工程]