基于自然电位的裂隙-基质系统溶质运移试验研究  

Experimental Study of Solute Transport in Fracture-matrix System Based on Self-potential

作　　者：王展 闫亚景 赵贵章 丁力 刘少康 李文曦 WANG Zhan;YAN Yajing;ZHAO Guizhang;DING Li;LIU Shaokang;LI Wenxi(School of Earth Geosciences and Engineering,North China University of Water Resources and Electric Power,Zhengzhou 450046,China)

机构地区：[1]华北水利水电大学地球科学与工程学院,河南郑州450046

出　　处：《华北水利水电大学学报（自然科学版）》2024年第6期97-108,共12页Journal of North China University of Water Resources and Electric Power：Natural Science Edition

基　　金：国家自然科学基金面上项目(41372260);南京水利科学研究院水文水资源与水利工程科学国家重点实验室“一带一路”水与可持续发展科技基金资助项目(2021490511);华北水利水电大学研究生教育创新计划基金项目(YK-2021-68)。

摘　　要：为了精细刻画岩石裂隙溶质运移过程及特征,构建了长×宽×高为0.20 m×0.03 m×0.50 m的砂箱模型,模型中间为裂隙,模型两侧为基质,两者共同构成了裂隙-基质系统。通过自然电位这一无损、快捷监测手段,针对不同粒径基质,在不同渗流速度下开展溶质运移试验,研究裂隙-基质系统溶质运移特征。结果表明:①在试验流速为0.0097~3.1959 mm/s时,裂隙-基质系统内裂隙渗透系数为5.5×10^(-2)m/s,与基质渗透系数2.4×10^(-3)、3.5×10^(-4)m/s相差不大,水流符合达西定律;随着基质粒径的不断减小,当裂隙渗透系数5.5×10^(-2)m/s与基质渗透系数3.6×10^(-5)m/s相差约3个数量级时,水流由达西流向非达西流转变。②在3种不同粒径的基质条件下,沿溶质运移方向,随着基质渗透系数的不断减小,裂隙域和基质域电极测点自然电位峰值不断减小,到达峰值的时间逐个增大。③随着流速的不断增大,裂隙域和基质域电极测点自然电位峰值出现时间提前,且同一系统流速下的裂隙域电极测点自然电位峰值的出现与基质域的相比历时较短。④通过自然电位峰值出现时间与溶质运移距离可以量化流速。计算所得流速值略小于系统测量流速值,其相关性拟合优度基本上均大于0.99,其中利用裂隙域电极测点自然电位计算所得的流速误差大多在10%以内,相对于基质域,计算精度更高,这与试验现象高度吻合,为探究裂隙-基质系统中的溶质运移过程提供了参考。In order to finely delineate the process and characteristics of solute transport in the rock fractures,a sandbox(0.20 m×0.03 m×0.50 m,L×W×H)was made by plexiglass plates.There is a fracture in the center of the sandbox,and on both sides of the fracture is the matrix.The fracture and matrix in the sandbox form a fracture-matrix system.The solute transport experiments were carried out under different grain size matrix seepage velocities by self-potential,a nondestructive and fast monitoring means,to study the solute transport characteristics of the fissure-matrix system.The results are as follows.①In the range of test flow rate 0.0097~3.1959 mm/s,the fracture permeability coefficient in the system is 5.5×10^(-2)m/s,and the difference between matrix permeability coefficient 2.4×10^(-3)m/s and 3.5×10^(-4)m/s steps is not significant,the flow conforms to Darcy′s law.And with the continuous reduction of matrix particle size,the water flow changes from Darcy flow to non-Darcy flow when the difference between fracture permeability coefficient 5.5×10^(-2)m/s and matrix permeability coefficient 3.6×10^(-5)m/s is about 3 orders of magnitude.②Follow the solute transport direction under three different matrix conditions with different particle sizes,the peak SP of the fracture domain and matrix domain electrode measurement points decreased continuously and the peak arrival time increased one by one with the decreasing matrix permeability coefficient.③With the increasing flow rate,the peak SP time of the slit domain and matrix domain electrode points appeared earlier and the peak SP time of the slit domain electrode measurement points at the same system flow rate was shorter compared with the matrix domain.④Flow velocity can be quantified by SP peak time and solute transport distance.The calculated flow velocity value is slightly smaller than the measured flow velocity value of the system,and the correlation fitting coefficient R^(2)is greater than 0.99,among which the error coefficient calculated by using t

关 键 词：自然电位 溶质运移 裂隙-基质系统 非达西流 

分 类 号：P641[天文地球—地质矿产勘探]