华北平原典型地段地面沉降演化特征与机理研究

发布时间：2018-03-28 18:34

本文选题：华北平原　切入点：地面沉降　出处：《中国地质》2017年06期

【摘要】：华北平原是世界上最大的地下水系统之一,地面沉降问题突出。由于沉积环境变化多样、地质条件差异性显著和人类开采活动强烈,使得该地区地面沉降成因机理复杂。本文采用卫星对地观测技术与传统手段相结合,监测地面沉降灾变过程,分析华北平原地面沉降发展历史和现状。结合应力-应变图解法及土工实验研究地面沉降差异性特征及滞后变形成因机理。取得了以下关键认识:(1)华北平原地面沉降空间分布差异性明显,沉降主要分布在平原区第四纪沉积凹陷,呈现东西分带、南北分段特点。地面沉降空间发展部分受到北东向和北西向构造控制。在沧县隆起区,地面沉降也比较发育,主要原因是沧县隆起在第四纪时期构造运动相对不活跃,沉积了较厚的第四系;存在与构造走向一致的3期古河道,该地区赋存丰富的地下水资源并被大量开采。(2)地面沉降发生发展与地下水开采历史密切相关,沉降主要压缩贡献层随地下水开采层位变化而变化。北京平原100 m以深地层对地面沉降贡献呈增加趋势。天津平原目前地面沉降的主要贡献层来自300 m以下地层。(3)气候干旱导致地下水补给量减少,同时增加了地下水的开采,因而是引起地面沉降的重要间接驱动因素。高层建筑荷载、基坑降排水、地热开采对地面沉降的影响应引起足够重视。(4)地面沉降具有很强的滞后性,最大滞后时间可达25年。除了渗透固结成因以外,土体蠕变是另外一个重要原因。更新世地层在不同荷载下,蠕变特征明显。沧县隆起晚更新世地层次固结可达到总变形28.3%。(5)土的物理性质、地下水位变化模式对土层变形特征具有重要影响。不同埋深地层在地下水位变化条件下的变形特征存在较大的差异(弹性、黏弹性、黏弹塑性)。浅部含水组呈现以弹性为主的变形特征。
[Abstract]:The North China Plain is one of the largest groundwater systems in the world, and the problem of land subsidence is prominent. The formation mechanism of land subsidence in this area is complicated. In this paper, the disaster process of land subsidence is monitored by the combination of satellite observation technology and traditional means. The history and present situation of land subsidence in North China Plain are analyzed. The difference characteristics of land subsidence and the formation mechanism of lag deformation are studied by means of stress-strain graphic method and geotechnical experiment. The following key understandings are obtained: 1) North China Plain land. The spatial distribution of settlement is obviously different, The subsidence is mainly distributed in Quaternary sedimentary sag of plain area, showing east-west zonation, north-south subdivision characteristic. The spatial development of land subsidence is partly controlled by NE and NW trending tectonics. In Cangxian uplift area, land subsidence is also relatively developed. The main reason is that the Cangxian uplift was relatively inactive in the Quaternary period and deposited thick Quaternary system. The occurrence and development of ground subsidence in this area is closely related to the history of groundwater exploitation. The contribution layer of subsidence mainly changes with the variation of groundwater mining horizon. The contribution of deep strata to ground subsidence in Beijing Plain is increasing. The main contribution layer of ground subsidence in Tianjin Plain at present comes from strata below 300 m. (III) reduced groundwater recharge due to climatic drought, At the same time, the groundwater mining is increased, so it is an important indirect driving factor to cause the ground subsidence. The influence of high-rise building load, foundation pit drainage and geothermal mining on the ground subsidence should be paid enough attention to. The maximum lag time can be up to 25 years. In addition to the causes of osmotic consolidation, soil creep is another important reason. The Pleistocene strata were subjected to different loads. The creep characteristics are obvious. The physical properties of the soil in the late Pleistocene of Cangxian uplift can reach the total deformation of 28.3. The variation model of groundwater level has an important influence on the deformation characteristics of soil layer, and there are great differences in deformation characteristics (elasticity, viscoelasticity, viscoelasticity) of different buried strata under the condition of groundwater level change. Viscoelastic-plastic. The shallow water-bearing group is characterized by elastic deformation.
【作者单位】：中国地质环境监测院;天津市地质调查研究院;首都师范大学;北京市水文地质工程地质大队;中国地质调查局;
【基金】：中国地质调查局地质调查项目(DD20160235,1212011140022,12120113011700) 国家自然科学基金项目(41572220)联合资助~~
【分类号】：P642.26

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