2015年6月，第21卷，第2期，243-254页
June2015，Vol.21，No.2，pp.243254 D0I: 10.16108/j.issn10067493.2014195
高校地质学报
Geological Jourmal of China Universities
上海市地下水位大幅抬升条件下土层变形特征分析
罗跃"，叶淑君，吴吉春'，焦瑄2，王寒梅2
1.南京大学地球科学与工程学院，南京210023；
2.国土资源部地面流降监测与防治重点实验室，上海地质调查研究院，上海200072
摘要：过去对地下水位持续下降条件的地面沉降研究较多，但对水位大幅持续抬升过程中的地面沉降研究较少。本文根据上海大量地面沉降、水位观测和钻孔资料，系统分析上海市90年代末以来地下水位大幅抬升条件下各土层的变形特征。自 1998年以来，上海市通过大幅压缩开采量、回灌地下水等措施使第二、三、四和五承压含水层水位分别平均抬升2.1m， 3.6m，12.4m，12.7m。水位的抬升使上海市地面沉降平均速率由1998年的12.2mm/a减小到2011年的1.83mm/a,减少85%。通过对27组分层标数据分析发现：现阶段主要压缩层位在第一、二软土层，年沉降速率为2~4mm/a；而第二含水层以下土层已经有少量回弹。在水位持续大幅抬升过程中，本文总结了两种变形特征：1）变形和水位变化基本同步，残余变形量非常小，变形可概化为线弹性变形，这种变形主要发生在第一、二、三和五承压含水层、第五和六弱透水层；2）压缩速率逐渐减小，无明显持续回弹趋势，有较大残余压缩量且存在变形滞后现象，变形可概化为弹塑性变形，这种变形主要发生在地第二、三和四弱透水层。第四承压含水层变形较复杂，两种变形特征都有。其中较大残余变形量主要由塑性贮水率比弹性贮水率大2个数量级引起；变形滞后主要由弱透水层申超孔隙水压力消散较慢起。本文研究成果对于掌握水位抬升过
程中土层变形方式、发生发展机理、预测未来地面沉降及地下水科学管理和资源评价具有重要意义。关键词：变形特征；弹性变形；滞后变形；地面沉降
中图分类号：P641.2
文献标识码：A
文章编号：1006-7493（2015）02-024312
CharacterizationofLandSubsidenceDuringRecoveryof
GroundwaterLevelsinShanghai
LUOYue',YEShujunt*,WUJichun',JIAOXun2,WANGHanmei 1. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
2. Key Laboratory of Land Subsidence Monitoring and Prevention, Ministry of Land and Resources,
Shanghai Geological Survey, Shanghai 200072, China
Abstract: Previous research was focused mainly on land subsidence during decline of groundwater levels, However, there have been few studies for land subsidence during the recovery of groundwater levels, This paper analyzes the deformation of each individual aquifer or aquitard after 1998, when groundwater levels in aquifers continued to rise due to reduced pumpage and increased artificial recharge. From 1998 to 2012, the average groundwater level in the second, third, fourth and fifth confined aquifers rose on average by 2.1 m, 3.6 m, 12.4 m and 12.7 m, respectively. Because of the recovery of groundwater levels in Shanghai, the land subsidence rate gradually decreased from 12.2 mm/a in 1998 to 1.83 mm/a in 2011. And the strata below the second confined aquifer even became uplifted after 2009. Land subsidence was primarily contributed by compaction of the first soft layer with a compaction rate of 24 mm/a in recent years. During the recovery of groundwater level, two kinds of deformation characteristics were recognized. One is that 收稿日期：2014-11-11；修回日期：2015-01-26
基金项目：国土资源部地面降监测与防治重点实验室开放基金（20140012)；国家自然科学基金（41272259）；江苏省自然科学基金（BK2012730）作者简介：罗跃，1985年生，博士研究生；E-mail:kuaikuaikaikai@126.com
*通讯作者：叶激君，教授；E-mail:sjyenju.edu.en