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  

Experimental study on the effect of pore water salinity and clay mineral type on the soil water characteristics of marine sediments

作　　者：付佳妮 于晓曦 傅晓敏 赵航 刘昌岭[4] 马云 刘乐乐 FU Jiani;YU Xiaoxi;FU Xiaomin;ZHAO Hang;LIU Changling;MA Yun;LIU Lele(Qingdao Key Laboratory of Groundwater Resources Protection and Rehabilitation,Qingdao,Shandong 266101,China;Key Laboratory of Geological Safety of Coastal Urban Underground Space,Ministry of Natural Resources,Qingdao,Shandong 266101,China;Qingdao Geo-Engineering Surveying Institute(Qingdao Geological Exploration Development Bureau),Qingdao,Shandong 266101,China;Key Laboratory of Gas Hydrate,Ministry of Natural Resources,Qingdao Institute of Marine Geology,China Geological Survey,Qingdao,Shandong 266237,China;School of Civil and Architectural Engineering,Yangtze Normal University,Chongqing 408100,China;Shandong Engineering Research Center of Marine Exploration and Conservation,Ocean University of China,Qingdao,Shandong 266100,China)

机构地区：[1]青岛市地下水资源保护与修复重点实验室,山东青岛266101 [2]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 [3]青岛地质工程勘察院(青岛地质勘查开发局),山东青岛266101 [4]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 [5]长江师范学院土木建筑工程学院,重庆408100 [6]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

出　　处：《地质学报》2024年第9期2795-2805,共11页Acta Geologica Sinica

基　　金：青岛市地下水资源保护与修复重点实验室开放基金项目(编号DXSKF2022Z03);山东省自然科学基金优秀青年基金项目(编号ZR2022YQ54);重庆市自然科学基金项目(编号cstc2019jcyj-msxmX0815);山东省泰山学者青年专家项目(编号tsqn202306297)联合资助的成果。

摘　　要：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。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.

关 键 词：天然气水合物 渗透率 海水入侵 盐度 黏土矿物 基质吸力 

分 类 号：P618.13[天文地球—矿床学]