长江河口深层软土含盐特征及其沉积环境分析  

Salt characteristics and sedimentary environment analysis of deep soft soil in the Changjiang River Estuary

作　　者：苟富刚[1,2] 龚绪龙 张岩[1,2] 杨露梅 刘彦[1,2] Gou Fugang;Gong Xulong;Zhang Yan;Yang Lumei;Liu Yan(Geological Survey of Jiangsu Province,Nanjing 210049,China;Key Laboratory of Earth Fissures Geological Disaster,Ministry of Natural Resources,Nanjing 210049,China)

机构地区：[1]江苏省地质调查研究院,江苏南京210049 [2]自然资源部地裂缝地质灾害重点实验室,江苏南京210049

出　　处：《海洋学报》2022年第4期12-22,共11页

基　　金：中国地质调查局地质大调查项目(1212011220005);国家自然科学基金(41772327);江苏省自然资源厅项目(JSZRHYKJ202106)。

摘　　要：软土的含盐特征是地基设计的一个重要指标,含盐特征主要受沉积环境控制,往往具有较强的地域性。以长江河口北翼海陆交互相软土为研究对象,采集多组土样进行室内试验,进行土体含盐特征、参数相关性及沉积环境分析。研究结果表明,软土含盐特征为NaCl型,含盐量均值为0.613%,以弱盐渍土为主,占比85.4%。含盐量、Cl^(-)含量、Na^(+)含量、K^(+)含量峰度检验符合正态分布,但偏度检验值坐落在拒绝域,不属于正态分布。其他离子假设检验偏度和峰度检验均不符合正态分布。软土含盐量与Cl_(–)含量相关性最高,与除了Ca^(2+)含量、CO_(3)^(2-)含量之外的离子相关性好。软土Cl_(–)含量与含盐量、SO_(4)^(2-)含量拟合以乘幂效果最佳;Cl^(–)含量与Na^(+)、Ca^(2+)、Mg^(2+)、K^(+)、HCO_(3)^(-)含量拟合以多项式拟合效果最佳。软土环境沉积为碱性。软土钠吸附比平均值为54.35,与标准海水的钠吸附比接近,说明软土层含盐特征保留了海水特征。随着深度的增加,软土钠吸附比有减小的趋势,这与软土形成时间有关,软土形成时代越老,渗透淋滤的时间越长。软土中Sr/Ba远大于1,说明土体沉积时受到了海水作用。软土浸出液中的γ_(Mg)/γ_(Ca)远高于地表淡水的γ_(Mg)/γ_(Ca)背景值,说明土体沉积时受到海水入侵。引入海水混合模型,计算了海水混合比例。海水混合比的低值主要分布于西部远离海岸区,该区土体沉积主要受长江河水控制。海水混合比的高值主要分布在滨海地区,该区土体沉积主要受海侵控制,海相属性更重。The salt-containing characteristics of soft soil are an important indicator of foundation design,and saltcontaining features are mainly protected by deposition environment,often with strong geographicalism.In the Changjiang River Ekimae,the softener of the Changjiang River Ekimae is a research object,collecting multi-sets of soil samples for indoor trials,and conducts salt-containing characteristics,parameter correlation and deposition environment analysis.The results show that the salt-containing salt is NaCl type,the salt content is 0.613%,mainly based on weak saline soil,accounting for 85.4%.The salt content,Cl^(-) content,Na^(+) content,K^(+) content peak test meets the regular distribution,but the reputation test value is located in the rejection domain,and does not belong to normal distribution.Other ion assumptions and peak tests do not comply with the right to distribution.The salt content of soft soil is highest in relationship with Cl^(-)content,and is good to ion-relevance to the Ca^(2+)content and CO_(3)^(2-).The content of the soil-solvent Cl-content and salt content,the SO_(4)^(2-) content is equipped with the highest multiplication effect;Cl-content is best fitted with Na^(+),Ca^(2+),Mg^(2+),K^(+),HCO_(3)^(-) contents fitted to polynomial fitting effect.The soft soil is deposited by an alkaline environment.The sodium adsorption ratio of soft soil is 54.35,which is close to the sodium adsorption ratio of seawater,indicating that the salt-containing characteristics retains the seawater characteristics,and with the increase of depth,soft soil sodium adsorption ratio has reduced trend.The soft soil formation time is related,the older the formation of soft soil,the longer the time of penetration.The Sr/Ba value of the soft soil is much greater than 1,indicating that the soil deposition environment is a marine environment.The γ_(Mg)/γ_(Ca) value in the soft soil leaching solution is much higher than the γ_(Mg)/γ_(Ca) background value,which is subjected to seawater dipping.The seawater mixing model is

关 键 词：沉积环境 含盐特征 软土 海水入侵 弱透水层 

分 类 号：P641.3[天文地球—地质矿产勘探] P343.5[天文地球—地质学]