连云港海相软土在孔隙水盐分溶脱环境下的固结特性  

Consolidation behaviors of soft marine clay in Lianyungang under desalination environment of pore water

作　　者：邓永锋[1,2] 岳喜兵 张彤炜[1,2] 刘松玉[1,2] 杨忠超[3] 

机构地区：[1]东南大学交通学院岩土工程研究所,江苏南京210096 [2]江苏省城市地下工程与环境安全重点实验室,江苏南京210096 [3]重庆交通大学水利水运工程教育部重点实验室,重庆400074

出　　处：《岩土工程学报》2015年第1期47-53,共7页Chinese Journal of Geotechnical Engineering

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)

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。The marine soft clays, the quaternary sediments, are widely deposited in the sea transgression/regression environment in Lianyungang, Jiangsu Province, whose behaviors are focused recently with the implementation of the coastal development strategy. The salinity of pore water during deposition is relatively high, and with the erosion of the surface or underground freshwater, the desalination of pore water occurs, whilst its effect on soil behaviors of the natural soft clays is still unclear. The piezo-cone penetration tests(CPTu) and physical property experiments of the soft clays with salinity of pore water of 0.1% and 4.9% at two sites, e.g. Lianyungang-Linyi highway and Linhai highway, are conducted. The higher strength of the soils with more salinity at the same depth is observed, but they have the similar deposition environment, ratios of water content to liquid limit, particle-size distributions and mineral compositions. To further clarify the effect of pore water, the paralleled percolation and oedometer tests with the synthetic solution and deionized water are performed. The results show that the parameters of oedometer modulus EOed, consolidation coefficient Cv and hydraulic conductivity k with the synthetic solution are higher than those with deionized water, while the compression index Cc, swelling index Cs and secondary consolidation coefficient Ca are on the contrary. Those results will deepen the understanding of behaviors of Lianyungang marine clays and provide the reference for the offshore engineering.

关 键 词：孔隙水盐分 溶脱环境 海相软土 固结特性 换盐与固结试验 

分 类 号：TU447[建筑科学—岩土工程] TU411[建筑科学—土工工程]