【作者】 王寒梅；

【导师】 钱光人； 沈照理；

【作者基本信息】 上海大学 ， 环境工程， 2013， 博士

【摘要】 本研究依托上海地区各类地面沉降的长期监测资料，根据上海地区地面沉降发生的机理，综合考虑地面沉降灾害对社会、经济可持续发展带来的严重影响，归纳出决定上海地区地面沉降风险程度的主要控制因子。据此开展地面沉降风险评价研究工作，确定风险评价要素，建立风险评价指标体系，构建风险评价模型，进行上海市地面沉降风险评价的实证研究；分析上海市采取地下水人工回灌措施对地面沉降风险的防治效果，并进一步探讨了地面沉降防治过程中地下水人工回灌对地质环境和地下水环境质量的影响，最终提出控制上海市地面沉降风险的分区管理对策。主要研究结论如下：1、通过对上海市地形地貌、基岩地质概况、第四纪地质、人文地质条件、工程地质条件等地质背景分析，结合近年来上海市地面沉降发展历史，分析上海市地面沉降发生的原因包括：受区内继承性特征新构造运动的影响，上海地区形成了二个凹陷和三个隆起，在凹陷带内第四系疏松堆积较厚，构成了地面沉降的物质基础；上海市地下水开采比较集中，地面沉降现象严重，并发育了数个沉降漏斗；通过数据分析表明，地下水的开发利用引起了地下水流场的变化，对地面沉降量的相对大小与分布特征产生影响。此外，工程建设活动也对地面沉降产生影响：以轨道交通为代表的线性工程建设对区域地面沉降空间格局影响较大；受深基坑降排水影响，浅部第Ⅰ承压含水层地下水位呈下降态势，中心城形成明显的地下水位漏斗，对地面沉降影响明显；城市建筑荷载对地面沉降具有长期影响。地面沉降造成上海市建筑物破坏、井口相对抬升、桥洞净空减少、市政设施破坏、港口码头或堤岸失效、江海水倒灌、洪涝、农田盐渍化等城市风险。2、根据上海地区地面沉降的特征与发生的机理分析，上海地区地面沉降地质灾害的风险要素由危险性和易损性这两个要素系列组成，以此要素建立上海市地面沉降风险评价指标体系。结合上海的实际情况，将上海地面沉降危险性增加的因素归纳为地面沉降易发程度、历史灾害强度、预测沉降速率、地势高程等指标；将上海地面沉降易损性增加的因素归纳为城市人口密度和单位面积的GDP以及建设用地所占比重，另外还包括市政设施：防汛墙长度、供水管密度、高架道路密度和轨道交通密度；影响易损性减小的因素为减灾防护的投入，包括单位面积减灾防护投入以及单位面积回灌投入。3、确定了上海地面沉降风险评价的主要内容为：危险性评价、易损性评价及风险评价三级模式，据此分别建立了上海地面沉降危险性评价模型、易损性评价模型和风险评价模型，其中，采用改进的模糊层次分析法建立适合上海地面沉降危险性评价模型；采用模糊综合评判法判别分区建立适合上海地面沉降易损性评价模型；采用统计分析法、基于Mapgis基础建立适合上海地面沉降风险性评价模型。4、利用危险性评价模型进行上海地面沉降危险性评价，得到结论：上海主要处于地面沉降危险性中等区，危险性高区主要分布于中心城区及与江浙两省交界的嘉定、金山局部地区，而地面沉降危险性低区主要分布在地质环境发育较好、地面沉降预测速率较低地区，以奉贤及青浦局部地区为代表。此外，三岛地区均属于地面沉降危险性中等区。5、利用易损性模型进行上海地面沉降易损性评价，得到结论：中心城区地面沉降易损性最为严重；原浦东新区也是地面沉降比较严重的地区，形成了高桥、张江、塘桥等区域性沉降漏斗，归为较高易损性区；宝山区和闵行区归为中等易损性区；松江区、原南汇区、嘉定区三个区归为较低易损性区；奉贤区、崇明县、金山区、青浦区四个区，归为低易损性区。6、利用风险性模型进行上海地面沉降风险性评价，得到结论：以中心城区为中心形成地面沉降的三级体系，即中心城区基本处于地面沉降风险高区，近郊区处于地面沉降较高至中等区，郊区处于地面沉降风险较低区。7、在地面沉降防治过程中，随着地下水人工回灌开发利用控制力度进一步加大，上海市第四承压含水层地下水位普遍呈现上升态势，且中心城、宝山区上升幅度大于10m以上；地下水人工回灌会导致回灌水源与地下水混合后的水质电导率下降，氧化还原电位升高，溶解氧含量有所升高，pH值有所降低，氯离子、重碳酸根离子的浓度有所下降，硫酸根、硝酸根离子的浓度有所升高，钠离子、钾离子、钙离子和镁离子的浓度均有所下降；此外，回灌初期地下水中总铁、总锰含量降低，且达到饮用水标准，但当回灌25-35天后发生含铁、含锰矿物组分重新溶出的现象，导致重金属浓度又超标；TOC、COD的浓度均逐渐升高，但并未超过回灌水源浓度值，未造成污染。因此，地下水人工回灌对于缓解地面沉降具有明显效果，对地下水水质有一定影响，但影响不大。8、针对上海市地面沉降的风险评价结果，本研究进一步提出建设上海市地面沉降管理区的风险管理对策。根据上海市地面沉降风险程度在空间上的分布特征，对应提出上海市地面沉降三级风险体系的管理区划，包括地面沉降重点防治管理区（Ⅰ区）、地面沉降次重点防治管理区（Ⅱ区）以及地面沉降一般防治管理区（Ⅲ区），详细划分各管理区所包含的范围，并从工程措施、规划控制、监测、预报、预警、规避、接受、防灾减灾教育等方面有针对性的提出各风险管理区的风险管理重点。更多还原

【Abstract】 Relied on a lot of long-term monitoring data of land subsidence, and according to themechanism of land subsidence in Shanghai area, this study has considered the serious impactof land subsidence disasters on social and economic sustainable development, andsummarized the main condition which can decide the risk level of land subsidence inShanghai. This study has carried out the research work of risk assessment on land subsidencein Shanghai, including the determination of the risk assessment elements, the establishment ofrisk assessment system and building risk assessment model. In addition, this study also hasanalysized the control effects of land subsidence risk by artificial recharge of groundwater. Atlast, this study has raised the partition management countermeasures on the risk of groundsubsidence in Shanghai. The main conclusions are as follows:1. Based on the geological background analysis of topography, bedrock geology,Quaternary geology, humanities geological conditions, and engineering geological conditionsin Shanghai, and combied with the history of land subsidence in recent years, this study hasanalyzed the causes of land subsidence in Shanghai, including: the Shanghai region formedtwo depressions and three ridges, in the Quaternary loose piled is thick in depressions band,which constitute the material basis of ground subsidence; the groundwater compareconcentrated in Shanghai, and it leads to serious land subsidence and sedimentation funneldevelopment as well as a number of ground fissure zones; the development and utilization ofgroundwater caused the changes of groundwater flow field, which caused a great impact onthe relative size and distribution of land subsidence. In addition, construction activities havean impact on land subsidence. Land subsidence has caused the damage of buildings, relativeuplift of wellhead, reduce of clearance dong, destroy of municipal facilities, failure of port orbank, intrusion of river water, flooding, salinization of farmland.2. According to the characteristics and mechanism of land subsidence in Shanghai, therisk factors of land subsidence in Shanghai include two elements, hazard and vulnerability.Combined with the actual situation in Shanghai, the increased hazard factors of landsubsidence can be summarized as prone extent of ground subsidence, historical disasterintensity, forecast sedimentation rate and terrain elevation; the increased vulnerability factors of land subsidence can be summarized as urban population density, GDP per unit area, theproportion of land for construction, as well as municipal facilities, including the length offlood wall, the density of water pipe, the density of elevated and rail traffic. The impactfactors of reduced vulnerability are the inputs of disaster protection, including the inputs ofdisaster protection and recharge per unit area.3. The main contents of risk assessment on land subsidence in Shanghai are as follows:the establishment of the model on hazard, vulnerability and risk assessment.The hazardassessment model was established by improved fuzzy AHP. The vulnerability assessmentmodel was established by discriminant fuzzy comprehensive evaluation method. The riskassessment model was established by statistical analysis method, and based on Mapgis.4. The conclusions of hazard assessment on land subsidence in Shanghai are as follows:Shanghai is mainly in the middle hazard areas of ground subsidence. The high-risk areas aremainly distributed in the central city and Jiading, Jinshan areas which are at the junction ofJiangsu and Zhejiang provinces. The low risk areas are mainly distributed in thewell-developed geological environment and the low prediction rate of land subsidence, suchas Qingpu, Fengxian areas. In addition, Sandao region are in the middle hazard areas of landsubsidence.5. The conclusions of vulnerability assessment on land subsidence in Shanghai are asfollows: the vulnerability of land subsidence in downtown is most serious. The landsubsidence is more serious in Pudong areas, leading to the regional subsidence funnel inGaoqiao, Zhangjiang, Tangqiao, which are classified as high vulnerability zone. Baoshan andMinhang are classified as moderate vulnerability zone. Songjiang, Nanhui, and JiadingDistricts are classified as the lower vulnerability zone. Fengxian, Chongming, Jinshan, andQingpu Districts are classified as the lowest vulnerability zone.6. The conclusions of risk assessment on land subsidence in Shanghai are as follows: thethree level of land subsidence system formed with the central city as the center. Thedowntown is in the highest risk areas of land subsidence, peri-urban areas are in the higherrisk areas of land subsidence to the middle risk areas, and the rural is in the low risk areas ofland subsidence.7. With the control of artificial groundwater recharge increased, the level of fourth confined aquifer groundwater was generally upward, and the center of the city, as well asBaoshan District, rise more than10m. Artificial groundwater recharge causes theconductivity of recharge water mixed with the groundwater decreased, redox potential rised,dissolved oxygen content increased, pH value decreased, the concentrations of chloride ionand bicarbonate ions decreased, the concentrations of sulfate and nitrate ions increased, theconcentrations of sodium, potassium calcium and magnesium ions decreased. In addition,with groundwater recharging, the total iron and manganese contents was decreased, which canmeet the drinking water standards. But with the recharge going for25-35days, the iron andmanganese mineral components was re-dissoluted, leading to the concentrations of heavymetals cannot meet the drinking water standards. The concentrations of TOC and COD weregradually increased, but did not exceed the back concentration of recharge source, which didnot cause any pollution. In addition, the water quality after artificial groundwater rechargemay contain hazardous chemical substances and pathogenic microorganisms, which arehazard on human health and ecosystems. Therefore, the groundwater quality after artificialrecharge has some effects to groundwater environment.8. With the risk assessment results of land subsidence in Shanghai, this study furtherproposed the risk management countermeasures of land subsidence in Shanghai. According tothe spatial distribution characteristics of land subsidence in Shanghai, this study raised thecountermeasures about three corresponding system of risk management divisions, includingthe focus area of prevention and management of land subsidence (Ⅰ area), the sub-focusarea of prevention and management of land subsidence (Ⅱ area), as well as the general areaof prevention and management of land subsidence (Ⅲ area). The detailed range of eachmanagement area was divided, and the risk management priorities in each managementdistrict was proposed targeted from the engineering measures, planning control, monitoring,forecasting and early warning, avoidance, acceptance and education of disaster prevention andmitigation.更多还原