【作者】 杨丽芝；

【导师】 张光辉； 李壮；

【作者基本信息】 中国地质科学院 ， 地质工程， 2009， 博士

【摘要】 海河平原第四系深层承压地下水（简称“深层水”,下同）超采问题,已经影响了区域经济社会又好又快发展,引起广泛关注。本文针对海河平原长期过量开采深层水导致地下水位不断下降,引发地面沉降等环境地质问题,选择德州深层水水位降落漏斗分布区作为重点研究区,以300～500m、500～800m和800～940m三个主要开采层位的深层水动态变化及其对应相关的粘性地层作为主要研究对象,应用地下水动力学、统计学方法和同位素技术,以深层水动态监测及其水化学组分和同位素采样测试分析作为获取源信息的主要技术手段,围绕“深层地下水位下降引起地面沉降的岩性及其结构和埋深阈值条件”和“大规模开采条件下深层承压水的补给来源与更新能力变化机制”这两个关键科学问题,重点开展了如下研究:①德州深层地下水漏斗区含水层概化的物理结构,包括含水层岩性特征、厚度变化、相互联系、空间分布规律;②德州深层地下水漏斗形成、演变过程及其与补给量、开采量与开采深度、地层岩性与结构之间关系;③人类活动对深层地下水补给及水位衰变影响机制与模式。研究取得如下主要认识和进展。1.德州深层地下水系统具有其典型性和特殊性,其开采层位包括6个含水层和7个粘性土层,地层结构复杂;开采深度为300～900m,最大开采深度达940m,是海河平原地下水开采最深的层位。目前,德州深层地下水位降落漏斗中心的水位已下降至-120m左右,水位埋深达140m。2005年在德州市范围内漏斗面积11068.8km²,与北部的沧州深层地下水位降落漏斗、文安-大成漏斗、天津漏斗相联,形成区域性复合式深层地下水位降落漏斗分布区。区内已出现地面沉降和地下咸水界面下侵和南移等环境地质问题。2.德州深层地下水开采资是由侧向径流补给、越流补给、含水层的弹性释水和粘性土层的压密释水的四部分组成,其中20.6%的侧向-越流补给量来自深层地下水系统外部的区域径流补给,反映深层地下水的自然更新能力。同位素数据分析表明,德州深层地下水是末次冰期盛期的大气降水补给,具有淋滤水特征,在其循环过程中,受到蒸发的影响和咸水的侵染,后期又遭遇多次海进干扰。水化学类型以HCO₃-Na型水占优势,具有高氟、高碘、高钠、低钙、低硬度、偏碱性的地下水化学特征,其同位素特征是氢氧稳定同位素低,氚含量低。3.相关分析结果表明,人工超采是德州深层地下水降落漏斗形成和演变的主导因素,开采量与漏斗中心水位之间非线性关系,呈三次项曲线特征。4.德州深层地下水赋存地层,虽然历经较长时间固结,属于超固结土,然而一旦增加外荷失水,附加应力超过前期固结应力,则将产生新的压密固结和释水。地面沉降与深层地下水位下降具有良好的相关性。根据地面沉降与深层地下水回归方程计算,德州深层地下水临界水位为-51.12m,容许水位降深为70.24m。5.在合理调控开采量条件下,深层地下水位降落漏斗中心水位是可以恢复的。每年减少60×10⁴～100×10⁴m³的开采量条件下,德州漏斗中心水位开始缓慢回升,至2020年前后德州漏斗中心消失。但是,深层地下水资源承载力具有不确定性和可变性,与开采技术条件、开采层位、地层结构之间关系较为密切。主要成果及创新点:①根据区内地层的埋藏深度、岩性、成因类型、沉积年代、土的物理力学性质、水力特征和水理性质,首次将800m以浅的地层划分为8个含水层、9个压缩层（弱透水层）和1个表土层,构建水-岩的水动力场研究体系,并将第三含水层至第五含水层及其间弱透水夹层概化为第Ⅲ含水岩组,将第六含水层至第八含水层及其间弱透水夹层概化为第Ⅳ含水岩组。第Ⅲ含水岩组和第Ⅳ含水岩组是德州深层水的主要开采层位。②初步查明德州主要开采层位的深层水储存资源主要形成于末次冰期盛期的大气降水补给,开采资源中20.6%的侧向径流补给和越流补给来自区域径流系统,含水层弹性释水和粘性土压密释水量分别占17.5%和61.9%。③揭示了德州深层水位降落漏斗形成和演变规律,并应用地学统计学方法识别和确定深层水位降落漏斗形成与变化的主导因素,为预测和制定合理调控对策研究奠定了坚实基础。④创建了德州深层水位降深漏斗变化与人类开采活动相关模型,并预测了不同开采条件下德州深层水位降深漏斗中心和漏斗分布区平均水位的变化趋势及可调控性;首次建立了德州地面沉降与深层水位之间关联关系,求得地面沉降的临界水位和容许水位降深,提出了德州深层地下水位降落漏斗的调控方案,为防控开采深层水引发环境地质灾害提供了重要的科学依据。更多还原

【Abstract】 It is widespread concerned that over-exploitation of Quaternary deep confined water (referred to "deep water", the same below) in Haihe Plain has already affected development of regional economy and society. Aimed at continuous drawdown of water table for over-exploitation and other geo-environmental problems, like land subsidence, this thesis selected distribution area of deep groundwater depression cone in Dezhou City as focus area. And it took variation of deep groundwater table and corresponding clay layers in the three main exploitation layers of 300～500 m, 500～800 m and 800～940 m as study targets. There were two key scientific points which should be cleared fist. One was lithology and structure of the formation where land subsidence happened due to drawdown of deep groundwater table and threshold value of buried depth. The other was recharge source of deep confined water and mechanism of variation of regeneration ability under large-scale mining condition. In this thesis, information was mainly achieved from deep groundwater dynamic monitoring, water chemistry composition and isotopic samples analysis. Using groundwater dynamic methods and isotopic technology, the thesis made following research. First, the thesis studied physic structure of aquifers in Dezhou deep groundwater depression cone area, including lithology characteristics, variation of thickness, correlation relationship and spatial distribution rules. Second, it studied formation and evolution process of deep groundwater depression cone and the affection of recharge, exploitation quantity, exploitation depth, characteristics and structure of the aquifers. Third, it studied impact mechanism and pattern of human activities on recharge of deep groundwater. Through these researches, the thesis achieved main knowledge and advances as follows.1. Dezhou deep groundwater system was typical and specific. Its exploitation formation included six aquifers and seven clay layers so that the structure was very complex. Depth o f exploitation was from 300 m to 900 m, with the maximum amounting to 940 m, and it was the deepest layer for exploiting in Haihe Plain. At present, water table of central deep groundwater depression cone dropped to about -120 m, water buried depth reached 140 m. In 2005, depression cone area was 11068.8km~2 in Dezhou. And it connected with Cangzhou deep groundwater depression cone, Wen’an-Dacheng depression cone and Tianjin depression cone, which became a regional compositive depression cone. In study area, geo-environmental problems emerged, like land subsidence and interface of salt groundwater downward and southward.2. Exploitation resources of Dezhou deep groundwater was composed of four parts, such as lateral runoff recharge, crossflow recharge, elastic releasing water of aquifers and compression releasing water of clay layers. Lateral runoff recharge took 20.6% of the total recharge and it came from regional runoff of external deep groundwater systems, reflecting natural regeneration ability of deep groundwater. Isotopic data showed that Dezhou deep groundwater was from precipitation in the last glacial period. It had the characteristics of leaching, and affected by evaporation and invasion of salt water in the process of water cycle. Latter, it was interfered by seawater invasion for many times. HCO3-Na type of water was prior than any other type, with high fluorine, high iodine, high sodium, low calcium, low hardness and alkalescent, low concentration of hydrogen and oxygen steady isotope and low tritium content as well.3. Results of correlation analysis showed that artificial over-exploitation was the main factor that resulted in formation and evolution of deep groundwater depression cone. The relationship between exploitation and water table of central depression cone was non-linear, but was characteristics of cubic polynomial curve instead.4. Strata of filling deep groundwater in Dezhou were well consolidated. Although being a long period of time after consolidation, releasing water would happen when pressure and additional stress exceeding pre-consolation stress. Land subsidence and drawdown of water table of deep groundwater had a good correlation relationship. Based on regression calculation of land subsidence and deep groundwater table, threshold value of deep groundwater table was -51.12 m, allowable drop of water table was 70.24m.5. When exploitation regulated reasonably, water table of central deep groundwater depression cone was recoverable. Under the condition of reducing exploitation for 60×10~4～100×10~4m~3 one year, water table of central depression cone began to rise slowly, and it would disappear in the year about 2020. But bearing capacity of deep groundwater resources was uncertain and various, for it closely related to condition of exploitation, mining horizon and the structure of formation.The main results and innovation were as follows.①According to buried depth of formation in research area, lithology, types of causes, deposition time, physical and mechanical properties of soil, water power features and hydrological characteristics, strata above 800 m were first dived into 8 aquifers, 9 compression layers (aquitard) and one layer of surface soil, water-rock dynamic research system was also built. At the same time, formations between the third aquifer and the fifth aquifer as well as aquitard were generalized into III bearing formation group. Aquifers and aquitard between the sixth aquifer and eighth aquifer were generalized into IV bearing formation group. The III and IV bearing formation groups were the main exploitation layers in Dezhou.②Storage resources of deep groundwater in Dezhou were mainly from precipitation recharge in the last glacial period. Exploitation resources mainly included lateral runoff recharge and crossflow recharge, which were from regional runoff systems, with 17.5% of elastic releasing water and 61.9% of compression releasing water.③The thesis revealed formation and evolution of Dezhou deep groundwater depression cone, and identified and determined dominant factors inducing formation and evolution of depression cone, using geo-statistical methods. The results laid a solid foundation to predict and make reasonable regulation countermeasures.④The thesis created the model revealing relationship between variation of Dezhou deep groundwater depression cone and artificial exploitation. And it predicted water table of central depression cone and mean water table under different exploitation condition. The thesis also analyzed regulation characteristics of deep groundwater. Besides, the thesis established the correlation relationship between land subsidence and water table of deep groundwater for the first time, and it calculated the threshold water table and allowable drawdown of water table. At last, in order to better prevent geo-environment disasters, the thesis put forward regulation projects for controlling deep groundwater depression cone in Dezhou.更多还原