首页|孔隙水盐度与黏土类型对海洋沉积物水分特征曲线的影响研究

孔隙水盐度与黏土类型对海洋沉积物水分特征曲线的影响研究

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海洋沉积物在天然气水合物分解或海水入侵过程中会出现孔隙水盐度及水饱和状态不断变化的现象,其透气和透水能力与沉积物水分特征曲线有关,然而孔隙水盐度变化对沉积物水分特征曲线的影响规律目前仍不够清楚.本文采用南海北部天然气水合物赋存区的海洋沉积物与实验室配置的混合沉积物进行试验,使用相对快速的离心机法,测定了不同基质吸力条件下的孔隙水饱和度,分析了黏土矿物类型和孔隙水盐度等因素对沉积物水分特征曲线的影响,选用被广泛使用的van Genuchten模型,率定了模型的拟合参数.结果表明:含黏土石英砂水分特征曲线基本不受黏土矿物种类的影响;南海北部海洋沉积物的黏土质量含量超过35％,但其水分特征曲线在两倍海水盐度范围内也几乎不受影响;对于南海北部海洋沉积物,van Genuchten模型系数a取值为0.00023 kPa-1,系数n和m取值分别为0.51和4.9.
Experimental study on the effect of pore water salinity and clay mineral type on the soil water characteristics of marine sediments
The dynamics of pore water salinity and sediment saturation degree are critical factors influencing fluid flow during gas hydrate production and seawater intrusion in marine environments.The percolation capacity of pore fluids is closely related to the soil water characteristics curve(SWCC).However,the influence of pore water salinity and clay mineral type on the SWCC of marine sediments remains poorly understood.This study investigates these effects through centrifuge tests on laboratory sand-clay mixtures and desalted marine sediments collected from the northern South China Sea(SCS),a region with natural gas hydrate occurrences.Pore water saturation was meticulously measured under varying matrix suctions conditions.Subsequently,the influence of pore water salinity and clay mineral type on the SWCC were systematically analyzed,followed by curve fitting using the van Genuchten model.The findings revealed that the SWCC of artificial quartz sands containing 20％clay by weight exhibited negligible dependence on the clay mineral type.Despite the clay content exceeding 35％,the SWCC of natural marine sediments from the northern SCS exhibited minimal variation when subjected to changes in pore water salinity.Upon applying the van Genuchten model to these natural marine sediments,the following parameter values were obtained:a=0.00023 kPa-1,n=0.51,and m=4.9.

natural gas hydratehydraulic permeabilityseawater intrusionsalinityclay mineralmatrix suction

付佳妮、于晓曦、傅晓敏、赵航、刘昌岭、马云、刘乐乐

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青岛市地下水资源保护与修复重点实验室,山东青岛,266101

自然资源部滨海城市地下空间地质安全重点实验室,山东青岛,266101

青岛地质工程勘察院(青岛地质勘查开发局),山东青岛,266101

自然资源部天然气水合物重点实验室,中国地质调查局青岛海洋地质研究所,山东青岛,266237

长江师范学院土木建筑工程学院,重庆,408100

中国海洋大学海底建设与保护山东省工程研究中心,山东青岛,266100

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天然气水合物 渗透率 海水入侵 盐度 黏土矿物 基质吸力

青岛市地下水资源保护与修复重点实验室开放基金项目山东省自然科学基金优秀青年基金项目重庆市自然科学基金项目山东省泰山学者青年专家项目

DXSKF2022Z03ZR2022YQ54cstc2019jcyjmsxmX0815tsqn202306297

2024

10.19762/j.cnki.dizhixuebao.2024186

地质学报
中国地质学会

地质学报

CSTPCD北大核心
影响因子：2.17
ISSN：0001-5717
年,卷(期)：2024.98(9)
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