基于MODFLOW SUB建立变渗透系数的地下水流地面沉降模型  

Modeling of Groundwater Flow-Land Subsidence with Variable Hydraulic Conductivity Based on MODFLOW-SUB

作　　者：孟世豪 崔亚莉[1] 田芳 罗勇 石鸿蕾 Meng Shihao;Cui Yali;Tian Fang;Luo Yong;Shi Honglei(School of Water Resources and Environment,China University of Geosciences(Beijing),Beijing 100083,China;Hydrogeology and Engineering Geology Team of Beijing(Geological Environment Monitoring Station of Beijing),Beijing 100195,China)

机构地区：[1]中国地质大学(北京)水资源与环境学院,北京100083 [2]北京市水文地质工程地质大队(北京市地质环境监测总站),北京100195

出　　处：《吉林大学学报（地球科学版）》2022年第2期550-559,共10页Journal of Jilin University：Earth Science Edition

基　　金：北京市财政专项(PXM2019_158305_000012)。

摘　　要：在基于MODFLOW SUB建立的地下水流地面沉降模型中,设定黏性土夹层内垂向渗透系数为常数,但黏性土夹层在压缩过程中,其垂向渗透系数会随之变化,因而运用该模型预测长期地面沉降可能与实际情况有较大差距.本次研究通过结合沉降过程中黏性土夹层内垂向渗透系数与水头的变化规律对SUB源代码进行改进,建立变渗透系数模型,并以美国地质调查局建立的加州羚羊谷典型结构为基础设计算例,分别对常渗透系数模型和变渗透系数模型进行模拟.结果显示:在开采初期的前20a,两模型具有较好的一致性;随着开采的持续进行,变渗透系模型计算的累计沉降量逐渐小于常渗透系数模型,80a内沉降量减少了约15.6%;随着开采量的增大,两模型产生差异的时间逐步提前且最终沉降差值增大;随着夹层厚度的增大,两模型产生差异的时间逐步滞后但最终沉降差值增大.由此表明,常渗透系数模型和变渗透系数模型在开采初期都具有很好的适用性,可以满足模型精度,但随着开采时间的延续,变渗透系数模型可以更好地反映实际压缩沉降过程.In the groundwater flow-land subsidence model based on MODFLOW-SUB,the vertical hydraulic conductivity of clay interbed is set as a constant.However,during the compression process of clay interbed,its vertical hydraulic conductivity will change accordingly,so the prediction of long-term land subsidence by using this model may be not realistically suitable.In this study,a variable hydraulic conductivity model was established through improving the source code of SUB combined with the change law of vertical hydraulic conductivity and the head of clay interbed during subsidence.Taking the typical structure of Antelope Valley in California established by the USGS(U.S.Geological Survey)as an example,the constant hydraulic conductivity model and the variable hydraulic conductivity model were used to simulate the process respectively.The results show that the two models have good consistency in the first 20 years of mining.With the continuous development of mining,the accumulated subsidence calculated by the variable system model is gradually smaller than that calculated by the constant model,and the accumulated subsidence in 80 years decreases by 15.6%.With the increase of mining amount,the time at which the two models differed is advanced and the final subsidence difference value is increased.With the increase of the interbed thickness,the time the two models differed gradually delays but the final subsidence difference value increases.The results indicate that both the constant model and the variable model have good applicability in the early stage of mining with desirable accuracy,but with the extension of mining time,the variable model can better reflect the actual compressive subsidence process.

关 键 词：地面沉降模型 垂向渗透系数 变参数 源代码改进 

分 类 号：P641.2[天文地球—地质矿产勘探]