连云港海相软土在孔隙水盐分溶脱环境下的固结特性

发布时间：2018-06-23 08:43

本文选题：孔隙水盐分 + 溶脱环境　；参考：《岩土工程学报》2015年01期

【摘要】：随着江苏沿海开发战略的实施,作为第四纪海进海退成因的典型区域性软土,连云港海相土的工程特性也日益引起关注。海相软土沉积过程中孔隙水盐分较高,而随着地表或地下淡水的冲蚀,孔隙水盐分发生溶脱,土的物理力学特性发生会改变,但是目前研究较少。以连云港海相沉积软土为研究对象,首先依托离岸线不同距离的连临高速与临海高等级公路,进行了多个场地的原位测试试验(CPTu)和孔隙水化学成分分析,对比后发现,两处场地具有相类似的沉积历史,含水比w0/wL、颗粒粒组与矿物成分基本相同;而相同深度处,孔隙水盐分高的场地土体强度较高。为了进一步探明其机理,设计了换盐和固结装置,即采用蒸馏水和取样点原位地下水(盐水)在一定水力梯度下淋洗原状土,淋洗后进行固结试验。结果表明:盐水淋洗的试样LYGOed1的压缩指数Cc、回弹指数Cs和次固结系数Ca小于蒸馏水淋洗试样LYGOed2,而LYGOed1的压缩模量EOed、固结系数Cv与渗透系数k大于LYGOed2,说明了盐分溶脱环境下,土的压缩性增大,次固结变形增大,固结时间变长,渗透系数变小。研究成果不仅能加深对连云港海相软土的认识,也为近岸或近海岩土工程设计提供参考。
[Abstract]:With the implementation of Jiangsu coastal development strategy, as a typical regional soft soil of Quaternary sea entry and regression, the engineering characteristics of Lianyungang marine facies soil have attracted more and more attention. In the process of marine soft soil deposition, the salt content of pore water is higher, but with the erosion of surface or underground fresh water, the salt of pore water dissolves and the physical and mechanical properties of soil change, but little research is done at present. Taking the marine sedimentary soft soil in Lianyungang as the research object, the in-situ test (CPTu) and the chemical composition analysis of pore water were carried out on the high speed highway and the high grade highway near the sea at different distances between the offshore line, and it was found that, The two sites have a similar sedimentary history, the water content ratio w _ 0 / w _ L, the particle group is basically the same as the mineral composition, and at the same depth, the soil strength of the site with high pore water and salt content is higher. In order to further study its mechanism, a salt exchange and consolidation device was designed, that is, distilled water and in-situ groundwater (brine) were used to wash undisturbed soil under a certain hydraulic gradient, and the consolidation tests were carried out after leaching. The results showed that the compression index Cc, springback index Cs and secondary consolidation coefficient Ca of LYGOed1 were lower than that of distilled water leaching sample LYGOed2, while the compression modulus of LYGOed1, consolidation coefficient CV and permeability coefficient k were higher than that of LYGOed2, which indicated that under the environment of salt solution desorption, the compression modulus of LYGOed1 was higher than that of LYGOed2, and the permeability coefficient of LYGOed1 was higher than that of LYGOed2. The compressibility of the soil increases, the secondary consolidation deformation increases, the consolidation time becomes longer and the permeability coefficient becomes smaller. The research results can not only deepen the understanding of marine soft soil in Lianyungang, but also provide reference for geotechnical engineering design near shore or offshore.
【作者单位】：东南大学交通学院岩土工程研究所;江苏省城市地下工程与环境安全重点实验室;重庆交通大学水利水运工程教育部重点实验室;
【基金】：国家自然科学基金项目(51378117,41330641) 水利水运工程教育部重点实验室暨国家内河航道整治工程技术研究中心开放基金项目(SLK2012B01)
【分类号】：TU447;TU411

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