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1.
基于DFOS的苏州第四纪沉积层变形及地面沉降监测分析 总被引：1，自引：0，他引：1
苏州地区广泛分布松散第四纪沉积物,大量抽取地下水导致了苏州大范围的地面沉降,严重影响了该区经济发展。本文在苏州盛泽200m钻孔内安装了分布式感测光纤,采用BOTDR及FBG等分布式光纤感测技术(DFOS),对第四纪沉积层压缩及地面沉降进行了长期的监测分析。分析结果表明:苏州盛泽地区第四纪土层可分为3个含水层(Af)及4个弱透水层(Ad),现阶段含水层压缩已不明显,主要压缩层为与抽水含水层相邻的两个隔水层,且与抽水含水层距离越近的部位压缩越明显; 第四纪沉积层的变形与抽水含水层孔隙水压变化基本一致,呈现出夏季压缩,冬季略回弹的趋势,并且存在滞后现象; 定义压缩度为各层累计压缩量与其自身厚度的比值,即每米压缩量。各土层沉降趋势可用压缩度判断,对于黏土隔水层沉降程度Ad2 Ad3 Ad4 Ad1,对于含水砂层,Af2为主要变形层,Af1及Af3变形基本稳定。DFOS技术为研究地面沉降机理,评价土层压缩变形潜力提供了十分先进的监测手段。 相似文献
2.
Land subsidence due to aquifer-system compaction accompanying groundwater extraction is a global hazard. Rising urban construction and groundwater demand necessitate increased awareness and better understanding of the geological problem. Motivated by the lack of laboratory-scale studies on this issue, an experimental investigation on the newly developed Tongchuan region, China, is presented. The study addresses the deformation behaviors of three soil samples, with the lithology of silty clay, silt, and fine sand, under the conditions of groundwater withdrawal and recharge using the GDS Consolidation Testing System. Results indicate that all three samples were characterized by elastic–plastic deformation under the conditions of withdrawing and recharging. The vertical deformation of the silty clay in the aquitard above the first confined aquifer was larger than those of the other two samples, and its deformation is a gradual and long process; thus, considerable attention should be paid to deformation in this aquitard due to the apparent creep effect and tiny rebound deformation. However, the settlement of the fine sand in the second confined aquifer cannot be ignored due to the great thickness of the aquifer. For the same soil, as the pore-water pressure declined, the unit rate of vertical deformation decreased gradually, whereas the creep effect of deformation in the later declining stage of pore-water pressure was more apparent than that in the former declining stage. These observations are highly important to the local government, which is developing measures to prevent and control subsidence. 相似文献
3.
地面沉降主要由深层地下水开采造成,含水层的压缩释水是深层地下水开采量主要构成来源,同时随其压缩变形孔隙比减小造成储水系数、渗透系数的减小,对弱透水层非弹性释水量、越流补给量造成影响。地面沉降过程中的水文地质参数非线性变化及对承压含水层系统的反馈作用也成为水文地质领域的前沿问题。为对地下水开采量、沉降量、地质参数变化以及给水能力变化之间的关系做一个较为定量定性的探究,以含水层压缩过程中的物理机制为依据,并基于沧州地区深层承压含水层的地下水位变化过程和水文地质参数,采用数学手段构建储水系数和渗透系数变化的一维非线性沉降模型。模拟结果显示随承压水头下降,储水系数最高可减小77%,含水层系统的给水能力和储水能力会随压缩变形减小50%甚至更多。研究成果为深入认识水文地质参数与应力变化相关关系、科学评价承压含水层地下水储水调节能力有重要借鉴意义。 相似文献
4.
Characterization of land subsidence induced by groundwater withdrawals in the plain of Beijing city,China 总被引：3，自引：1，他引：2
Youquan Zhang Huili Gong Zhaoqin Gu Rong Wang Xiaojuan Li Wenji Zhao 《Hydrogeology Journal》2014,22(2):397-409
The plain of Beijing city in China suffers severe land subsidence owing to groundwater overdraft. The maximum subsidence rate could reach 6 cm/year through the 2000s. An integrated subsidence-monitoring program was designed, including levelling survey, borehole extensometers and multilayer monitoring of groundwater level, with the aim to understand both hydrological and mechanical processes and to characterize the land subsidence. From multilayer compaction monitoring, the major compression layers were identified. The major strata contributing to compression deformation are the second (64.5–82.3 m) and third (102–117 m) aquitards, which contributed around 39 % of the total subsidence. Meanwhile, irrecoverable deformations were also observed in the second (82.3–102 m) and third (117–148 m) confined aquifers; they exhibit elasto-plastic mechanical behavior, which is attributed to the thin beds of silt or silty clay. Stress–strain analysis and oedometer tests were conducted to study the aquifer-system response to pumping and to estimate the specific storage of the major hydrogeologic units. The results reveal the creep behavior and elasto-plastic, visco-elasto-plastic mechanical behavior of the aquitards at different depths. The compressibility of the aquitards in the inelastic range is about one order of magnitude larger than for the elastic range. 相似文献
5.
Land subsidence in China 总被引：19，自引：0，他引：19
Land subsidence in China occurs in different regions. It is primarily caused by excessive groundwater withdrawal. Other reasons
for the subsidence include the oil, warm groundwater withdrawal and the neotectonic movement. The common characteristics of
land subsidence in China are slow, accumulative, irreversible, and other unique properties. The range of subsidence still
keeps extending and the accumulative subsidence increasing though some measures taken. Adjustment of the aquifer exploitation
practice is a subsidiary way to control land subsidence, but it cannot solve this problem completely. In a specfic way of
groundwater changing, the contribution of a certain soil layer to the total subsidence depends on its compressibility and
thickness. Besides the elasticity, both cohesive soil layers (aquitards) and sand layers (aquifers) are observed to be plastic
and creep when the groundwater level fluctuates in a specific way, which often leads to subsidence delay. 相似文献
6.
Investigation into subsidence hazards due to groundwater pumping from Aquifer II in Changzhou,China 总被引：2，自引：1，他引：1
Ye-Shuang Xu Yao Yuan Shui-Long Shen Zhen-Yu Yin Huai-Na Wu Lei Ma 《Natural Hazards》2015,78(1):281-296
This paper presents an investigation into increased deformation of Aquifer II caused by groundwater pumping from the aquifer in Changzhou, China. As groundwater levels of aquifers have been decreasing in recent decades due to uncontrolled water pumping, land subsidence is becoming a serious geohazard in Changzhou. Based on recently reported field data, the compression of aquitards has not increased compared to that of aquifers with the same scale of layer thickness. The Cosserat continuum model was adopted to analyse the observed phenomenon in this study. A classic Cauchy continuum model is also used for comparison. The comparison between these two models indicates that the proposed approach can interpret the increased deformation well, and the classic Cauchy continuum model underestimates the aquifer deformation as it does not consider shear displacement and macro-rotation. A discussion on the relationship between the groundwater level in the aquifer and subsidence is then undertaken. The results show that the severity of the annual subsidence is correlated with the variation in groundwater level in Aquifer II. To mitigate the subsidence hazards, countermeasures should be adopted to avoid the shear stress in aquifers which results from the high hydraulic gradient, by the appropriate allocation of pumping wells and by restricting groundwater withdrawal volume from each pumping operation. 相似文献
7.
天津市地下水流-地面沉降耦合模型 总被引：6，自引：0，他引：6
天津市平原区地面沉降主要由地下水大量开采引起,影响范围广、危害大,已成为天津市主要的环境地质问题。分析了研究区的水文地质条件,结合地下水开发利用状况,将研究区概化为6个含水层组,地下水流考虑三维非稳定流,地面沉降选用一维固结压缩模型,运用地下水流模型Modflow 2005和地面沉降模拟模块 Sub,建立了天津市平原区地下水流-地面沉降数值耦合模型,模型面积为1.1×104 km2,利用1998-2008年地下水位等值线、过程线、地面沉降过程线等资料对模型进行了识别。模拟期的地下水均衡分析表明,在多年开采条件下,越流补给、压缩释水、侧向边界流入分别占深层含水层补给量的41.84％、32.15％和24.17％。将调试后的模型应用于南水北调实施后地下水控采条件下的地面沉降趋势预测,显示出停采或减少地下水的开采,有利于减缓地面沉降下降速度,且表现出开采层位越往下,地面沉降恢复难度越大的变化趋势。 相似文献
8.
弱透水层与含水层相互作用是国际水文地质学界关注的热点问题,特别是黏性土弱透水层与孔隙含水层的相互作用。近年来,在自然沉积、过量开采地下水、现代化农业机械与建筑业重型机械应用等自然与人为活动影响下,黏土弱透水层会发生有效应力增加、孔隙结构变形和孔隙度减少、渗透性降低、溶解氧和贮水能力减少以及侧向和垂向排水等的压实作用,导致地下水污染、地面沉降等环境问题的发生。本文重点介绍了黏性土弱透水层压实作用的原理,分析了地下水系统中4种不同状态下沉积物压实与孔隙流体压力的关系,基于压实物理模拟和数值模拟两个方面对压实作用的研究方法与技术进行了系统总结,随后探讨了压实作用下黏性土弱透水层对地下水水量与水质的影响,并对此研究的发展趋势及其在地球科学、环境科学等研究领域的潜在应用提出了展望。 相似文献
9.
The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007–2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use. 相似文献
10.
The application of satellite differential SAR interferometry-derived ground displacements in hydrogeology 总被引：7，自引：1，他引：6
The application of satellite differential synthetic aperture radar (SAR) interferometry, principally coherent (InSAR) and to a lesser extent, persistent-scatterer (PSI) techniques to hydrogeologic studies has improved capabilities to map, monitor, analyze, and simulate groundwater flow, aquifer-system compaction and land subsidence. A number of investigations over the previous decade show how the spatially detailed images of ground displacements measured with InSAR have advanced hydrogeologic understanding, especially when a time series of images is used in conjunction with histories of changes in water levels and management practices. Important advances include: (1) identifying structural or lithostratigraphic boundaries (e.g. faults or transitional facies) of groundwater flow and deformation; (2) defining the material and hydraulic heterogeneity of deforming aquifer-systems; (3) estimating system properties (e.g. storage coefficients and hydraulic conductivities); and (4) constraining numerical models of groundwater flow, aquifer-system compaction, and land subsidence. As a component of an integrated approach to hydrogeologic monitoring and characterization of unconsolidated alluvial groundwater basins differential SAR interferometry contributes unique information that can facilitate improved management of groundwater resources. Future satellite SAR missions specifically designed for differential interferometry will enhance these contributions. 相似文献
11.
Yun Zhang Yu-Qun Xue Ji-Chun Wu Shu-Jun Ye Zi-Xin Wei Qin-Fen Li Jun Yu 《Engineering Geology》2007,90(3-4):160-173
Excessive groundwater pumpage has caused regional cones of depression and severe land subsidence in the Southern Yangtse Delta, China. The characteristics of aquifer system compaction are complex because of the difference in the types, compositions and structures of the soils that the hydrostratigraphic units are composed of, and in the histories of groundwater level change the hydrostratigraphic units have experienced. Based on the data measured from extensometer groups and observation wells, the characteristics of deformation for individual hydrostratigraphic units are analyzed. The results show that different hydrostratigraphic units have different kinds of deformation and that an identical unit may also present different deformation characteristics, such as elasticity, elasto-plasticity, and visco-elasto-plasticity, at different sites of the cone of depression or in different periods. If the groundwater level rises continuously and remains constant later, the aquifers and the aquitard units that consist of hard clay primarily exhibit elastic behaviour, but the aquitard units that consist of soft clay deform plastically and by creep and exhibit visco-elasto-plastic behaviour. If the groundwater level falls but is much higher than the previous lowest value, aquifers and aquitards consisting of hard clay exhibit elasto-plastic behaviour. If the groundwater level falls below the previous lowest value, aquifers and aquitards consisting of hard clay deform plastically and by creep and exhibit visco-elasto-plastic behaviour. 相似文献
12.
Excessive groundwater withdrawal and resultant land subsidence in the Su-Xi-Chang area,China 总被引：5，自引：1，他引：4
Yun Zhang Yu-Qun Xue Ji-Chun Wu Xiao-Qing Shi Jun Yu 《Environmental Earth Sciences》2010,61(6):1135-1143
Excessive groundwater withdrawal has caused severe land subsidence in the Su-Xi-Chang (SXC) area, China. The restriction and
prohibition on groundwater pumping have been carried out since the late 1990s. Based on the latest updated field data, the
changing pattern of groundwater level and the distribution of land subsidence are analyzed. The distribution of land subsidence
in SXC is closely related to that of the cone of depression in the second confined aquifer in time and space. But land subsidence
is not in synchronization with the changing groundwater level. Both aquitards and aquifers compacted continuously in the early
period of groundwater level rising and behaved as creep materials. A series of laboratory tests were conducted on aquifer
sands, which indicated that the creep deformation under virgin compression is much greater than that under recompression and
unloading, and that the creep of sands decreases rapidly with the cycles of repeating load. The test results reveal the mechanism
of sand creep under the condition of long-term groundwater pumpage. As a consequence of the restriction and prohibition on
groundwater pumping, groundwater level has obviously recovered in the vast majority of the SXC area, and land subsidence has
slowed down and even a little rebound has occurred in some sites in Suzhou and Changzhou. If the pumpage is strictly limited
continuously, the groundwater level will not decline below the historical lowest value but fluctuate within a certain range.
In such a case, land subsidence in SXC will no longer develop obviously. 相似文献
13.
Xiaoqing Shi Jichun Wu Shujun Ye Yun Zhang Yuqun Xue Zixin Wei Qinfen Li Jun Yu 《Engineering Geology》2008,100(1-2):27-42
Su-Xi-Chang area and Shanghai City, located in the south of Yangtze Delta, China, has subsided due to groundwater overpumping. Because of the regional scale of the groundwater exploitation, cone of depression and land subsidence at present, Su-Xi-Chang area and Shanghai City are treated as a single area for land subsidence study to avoid the uncertainty of boundary condition due to the regionalism. The characteristics of aquifer system compaction are complex because of the difference in the types, compositions and structures of the soils that the hydrostratigraphic units are composed of, and in the histories of groundwater level change the hydrostratigraphic units have experienced. Considering the fact that different hydrostratigraphic units have different kinds of deformation and that an identical unit may also present different deformation characteristics, such as elasticity, elasto-plasticity, and visco-elasto-plasticity, at different sites of the cone of depression or in different periods, corresponding constitutive laws have been adopted. This avoids the shortcomings of the previous research that the same constitutive law was adopted in all the hydrostratigraphic units during the entire time period. A coupled flow and subsidence model, which includes a three-dimensional flow model with variable coefficients and a one-dimensional (vertical) subsidence model, is built according to the complicated hydrological condition in the region. The simulation model is calibrated using observed data, which include compression of individual strata from groups of extensometers and groundwater levels from observation wells from 1995 to 2002. The model reproduced that the primary subsidence layer in Shanghai shifts from the shallow aquitard to the fourth confined aquifer because of the groundwater yield variations and the change of exploitation aquifers. However the third aquitard was the primary subsidence layer in Su-Xi-Chang area and the compaction deformation of the sandy aquifers was remarkable. The simulation results could provide some reasonable advice about groundwater exploitation in the future. 相似文献
14.
上海市曾遭受了严重的地面沉降灾害,主要由于浅部含水层开采引发浅部土层固结所致。之后采取了回灌浅部含水层并转向开采深部含水层的措施,地面沉降得到了有效控制。但21世纪初,通过水位及分层沉降监测,发现随着开采量增加,深部含水层也会成为主要压密土层。其变形呈现出显著的非线性压密特征,即使水位普遍抬升,压密仍然持续,开展其固结压密机理模型研究对地面沉降防治十分必要。传统太沙基理论认为砂土骨架是瞬时变形的,忽略了流变性本质,因此无法解释该现象。基于国内外学者的研究,考虑了前期固结压力前后流变性的差异,建立了深部含水层黏弹塑固结压密模型。通过试验获取了相关参数,结合塘桥F16分层标监测结果,对第四含水层长期压密变形进行了模拟。模拟结果很好地反映了含水层长期非线性压密行为,研究结果对指导防治地面沉降有实际意义。 相似文献
15.
Wei-Chia Hung Cheinway Hwang Chung-Pai Chang Jiun-Yee Yen Chih-Hsi Liu Wan-Huei Yang 《Environmental Earth Sciences》2010,59(7):1535-1548
During 1992–2007, excessive pumping of groundwater caused large-scale aquifer-system compaction and land subsidence in the
Choshui River Alluvial Fan, especially in the area of Yunlin county. The subsidence impedes surface-water runoff and endangers
the operation of Taiwan High Speed Rail. Leveling, Global Positioning System (GPS), multi-level compaction monitoring well,
and Differential Interferometric Synthetic Aperture Radar (DInSAR) are used to study the extent of subsidence in Yunlin and
its mechanism. These sensors complement each other in spatial and temporal resolutions. A leveling network totaling 434 km
in length was deployed to derive subsidence at every 1.5 km along the routes, and the result is accurate to few mm and shows
a basin-like subsidence pattern centering at Tuku Township. Four multi-level compaction monitoring wells, co-located with
GPS pillars, detect compactions at different depths, showing that the aquifer-system compaction (the cause of subsidence)
occurs mostly below depths >200 m, where reduction of groundwater pumping is most needed. The vertical displacements from
GPS and leveling agree to within 1 cm, and are larger than the cumulative compaction detected by the compaction-monitoring
wells, suggesting that compaction also occurs below 300 m (the depth of the wells). The vertical displacements derived using
DInSAR and 8 ENVISAT SAR images agree with the leveling result to 1–2 cm. 相似文献
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18.
Shujun Ye Yue Luo Jichun Wu Xuexin Yan Hanmei Wang Xun Jiao Pietro Teatini 《Hydrogeology Journal》2016,24(3):695-709
Shanghai, in China, has experienced two periods of rapid land subsidence mainly caused by groundwater exploitation related to economic and population growth. The first period occurred during 1956–1965 and was characterized by an average land subsidence rate of 83 mm/yr, and the second period occurred during 1990–1998 with an average subsidence rate of 16 mm/yr. Owing to the establishment of monitoring networks for groundwater levels and land subsidence, a valuable dataset has been collected since the 1960s and used to develop regional land subsidence models applied to manage groundwater resources and mitigate land subsidence. The previous geomechanical modeling approaches to simulate land subsidence were based on one-dimensional (1D) vertical stress and deformation. In this study, a numerical model of land subsidence is developed to simulate explicitly coupled three-dimensional (3D) groundwater flow and 3D aquifer-system displacements in downtown Shanghai from 30 December 1979 to 30 December 1995. The model is calibrated using piezometric, geodetic-leveling, and borehole extensometer measurements made during the 16-year simulation period. The 3D model satisfactorily reproduces the measured piezometric and deformation observations. For the first time, the capability exists to provide some preliminary estimations on the horizontal displacement field associated with the well-known land subsidence in Shanghai and for which no measurements are available. The simulated horizontal displacements peak at 11 mm, i.e. less than 10 % of the simulated maximum land subsidence, and seems too small to seriously damage infrastructure such as the subways (metro lines) in the center area of Shanghai. 相似文献
19.
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2.1 m,
3.6 m, 12.4 m, 12.7 m。水位的抬升使上海市地面沉降平均速率由1998年的12.2 mm/a减小到2011年的1.83 mm/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2~4 mm/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中超孔隙水压力消散较慢引起。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。 相似文献
20.
Mechanics of land subsidence due to groundwater pumping 总被引：1，自引：0，他引：1
This paper presents the formulation of the basic mechanics governing the changes in stress states from groundwater pumping and comparisons among predicted land subsidence from this mechanics with existing analyses and field data. Land subsidence is a growing, global problem caused by petroleum and groundwater withdrawal, mining operations, natural settlement, hydro‐compaction, settlement of collapsible soils, settlement of organic soils and sinkholes. This paper is concerned with the land subsidence due to groundwater level decline by groundwater pumping. It is shown that the stress state consists of asymmetric stresses that are best simulated by a Cosserat rather than a Cauchy continuum. Land subsidence from groundwater level decline consists of vertical compression (consolidation), shear displacement and macro‐rotation. The latter occurs when conditions are favorable (e.g. at a vertical interface) for the micro‐rotation imposed by asymmetric stresses to become macro‐rotation. When the length of the cone of depression is beyond √2 times the thickness of the aquifer, simple shear on vertical planes with rotation is the predominant deformation mode. Otherwise, simple shear on horizontal planes is present. The predicted subsidence using the mechanics developed in this paper compares well with data from satellite‐borne interferometric synthetic aperture radar. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献