Showing papers on "Groundwater-related subsidence published in 2004"

Land subsidence due to groundwater drawdown in Shanghai

Abstract: INTRODUCTION Shanghai is located on the deltaic deposit of the Yangtze River, as illustrated in Fig 1 Fig 2 shows the main geological strata The total thickness of the Quaternary deposit is about 300 m (Shanghai Geology Office, 1976, 1979) Excessive pumping of the groundwater caused compression of the Quaternary deposit, and subsidence in Shanghai Although several countermeasures, including recharge of the groundwater, have been adopted to mitigate the rate of subsidence, up to the present the recorded cumulative subsidence has been 2–3 m in the central area of Shanghai This subsidence has caused a lot of social problems The immediate problem is the increase in the possibility of flooding From 1981 to 1994, rainfall flooding occurred 22 times, at a rate of almost twice per year (Liu, 2001) The possibility of tidal flooding also increased From 1956, the height of the dike along the coast line was increased four times, with the crest elevation rising from 5 m to 68 m Other problems caused by the land subsidence are damage to the sewerage system, road, buildings, and subway tunnels etc In Shanghai the monitoring of land subsidence started in 1921 The history of land subsidence in the urban area of Shanghai can be divided into two periods: namely a rapid subsidence period (1921–1965) and a controlled period (1965–present) (Zhang & Han, 2002) However, there has been a tendency for the subsidence rate to increase after 1990 In this paper, the mechanism of land subsidence due to excessive pumping of groundwater is discussed first Then the measured field data are presented, and the relationship between groundwater pumping and land subsidence is discussed

Topographic response to mantle lithosphere removal in the southern Sierra Nevada region, California

Abstract: Geological studies of mantle xenoliths entrained in late Neogene‐Quaternary lavas from the southern Sierra Nevada region and regional geophysical studies suggest that the highdensity mantle lithosphere that formed beneath the Sierra Nevada batholith in conjunction with arc magmatism is being convectively removed as a ‘‘drip’’ structure. This structure, as imaged seismically, is roughly cylindrical in shape with a diameter of ;100 km, and extends to ;225 km depth. Centered above this structure is a region ;120 km in diameter that is undergoing active subsidence relative to adjacent regions. Such subsidence is seen in the active fluvial-alluvial sediment flooding of mountainous topography of the southwestern Sierra and in the development of the adjacent Tulare Lake basin of the San Joaquin Valley. Dynamic modeling of such upper-mantle drip structures predicts a phase of overlying surface subsidence during the most vigorous phase of drip formation. The southern Sierra upper mantle drip and the overlying crust appear to be in this phase of their dynamically coupled evolution.

Summary of hydrogeology and simulation of ground-water flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system, Texas

Abstract: The northern part of the Gulf Coast aquifer system in Texas, which includes the Chicot, Evangeline, and Jasper aquifers, supplies most of the water used for industrial, municipal, agricultural, and commercial purposes for an approximately 25,000square-mile (mi2) area that includes the Beaumont and Houston metropolitan areas. The area has an abundant amount of potable ground water, but withdrawals of large quantities of ground water have resulted in potentiometric-surface declines in the Chicot, Evangeline, and Jasper aquifers and land-surface subsidence from depressurization and compaction of clay layers interbedded in the aquifer sediments. This fact sheet summarizes a study done in cooperation with the Texas Water Development Board (TWDB) and the Harris-Galveston Coastal Subsidence District (HGCSD) as a part of the TWDB Ground-Water Availability Modeling (or Model) (GAM) program. The study was designed to develop and test a ground-water-flow model of the northern part of the Gulf Coast aquifer system in the GAM area (fig. 1) that waterresource managers can use as a tool to address future groundwater-availability issues.

Profiling Function for Surface Subsidence Prediction in Mining Inclined Coal Seams

Abstract: A new profiling function is proposed to predict the value of surface subsidence over longwall panel in the inclined seams. This function was used at the Parvada-2 mine in Tabass coal region, Iran. The calculated results are compared with the real movements obtained by field measurements.

Modeling of Subsidence and Reservoir Compaction under Waterflood Operations

Abstract: A full-field, three-dimensional (3D) computer model has been developed to numerically simulate reservoir compaction and surface subsidence for a weak, water-sensitive, hydrocarbon reservoir during field-wide water-injection operations. The developed model was used for modeling the compaction and subsidence processes under waterflood operations at the Ekofisk Field in the North Sea. The model was thoroughly validated through the comparison of model results to extensive field measurements with good agreement being achieved. The validated model has been successfully employed as a tool to forecast subsidence and to assist in the development of a subsidence risk assessment. For practical field applications, important quantitative information, that includes reservoir compaction, seafloor subsidence, and seafloor horizontal movement, may be generated from the full-field, 3D model and is presented in this paper.

Engineering-geological map of the wider Thessaloniki area, Greece

Abstract: The preparation and compilation of a 1:10,000 scale engineering geological map of the wider Thessaloniki area is discussed This map includes the range of values of the geomechanical characteristics of the 13 engineering geological units distinguished Greater detail was available in the inhabited and industrial areas where many of the 1,300 boreholes studied had been drilled Particular emphasis was given to the earth fill unit, which in places is up to 20 m thick Some of the underlying Quaternary units are aquifers and severe pumping has resulted in both a lowering of the groundwater level and surface subsidence The subsidence was most prominent in the Sindos–Kalohori–Axios River zone and required the construction of an embankment along the coast

Applying probability distribution density function to predict the surface subsidence caused by subcritical extraction

Abstract: It was found that the moving probability of the shiver in the discrete medium caused by super-subcritical extraction approach to probability density function of normal distribution through theory analysis and computer simulation.The probability distribution density function method was presented to predict the surface movement and deformation caused by super-subcritical extraction.The prediction data were compared with the actual observation data,it was concluded that the prediction relative error is less than 10%, if the prediction parameters were exactly selected.It was resolved that the problem using probability integration method to predict the surface subsidence caused by super-subcritical extraction is greater than the actual surface subsidence.

Technical Analysis of the Remote Sensing Monitoring for Coal-mining Subsidence Based on D-InSAR

Abstract: Based on analysis of the present situation of the technologies in the mining subsidence monitoring,the developments of SAR interferometry (InSAR),differential InSAR(D-InSAR)and their applications in the surface subsidence monitoring,the features and advantages of D-InSAR applied in coal-mining subsidence monitoring are analyzed.It is also pointed out that the actual goals of D-InSAR monitoring for coal-mining subsidence include the process analysis of surface subsidence evolution in coal mines,the dynamic monitoring and analysis of surface subsidence in active mining zone and the DEM data update of coal mines.The key technologies that need to be solved include obtaining and selection of SAR data sources,methods for SAR data processing,ground assistant,data precision and reliability analysis and integral analysis on multi-source information.As an important part of Digital Mine,D-InSAR could be more effective in production guiding,mine planning and the sustainable development of coal mines.

Composition of groundwater resources in deep-seated aquifers under the condition of land subsidence in Tianjin Plain

Abstract: On the basis of the monitoring results of land subsidence and calculation of deep groundwater resources by using water balance method, it is shown that the leakage recharge from its upper shallow groundwater account for approximately 38.2%, drainage of the clay layers, about 41.3%, water release from the aquifers, around 5.6%, and lateral inflow, some 14.9%, of the total groundwater resources. In order to control the land subsidence, adjusting three dimensional exploitive positions and moderately utilizing the leakage recharge from its upper shallow groundwater play a key role in realizing the sustainable development of deep groundwater resources in this area.

The law of tectonic stress mining ground surface subsidence and its engineering treatment method

Abstract: The ground surface subsidence caused by underground excavation in which has obvious tectonic stress effect is the coupling effective results of tectonic stress and self-weight stress (Because) it has different mechanical mechanism, this subsidence expresses special macroscopic destruction characteristics From the observation and analysis of macroscopic destruction characteristics, the mechanical essence of tectonic stress ground surface subsidence caused by underground excavation and established it′s mechanical model was revealed, it is shown that the law of self-weight stress ground surface subsidence caused by underground excavation be not suitable for the study of tectonic stress ground surface subsidence caused by underground excavation Thus the concept of tectonic stress general changed stress must be introduced into the anticipate formula system of tectonic stress ground surface subsidence caused by underground excavation From the viewpoint of engineering application, the synthetical effect of self-weight stress and general changed stress should be considered to investigate the ground surface subsidence caused by underground excavation The developing direction of theoretical research on tectonic stress ground surface subsidence caused by underground excavation is also pointed out in this paper

InSAR-based land subsidence map for bangkok, Thailand

Abstract: The metropolis of Bangkok is facing serious problems with land subsidence caused by over-exploitation of groundwater. Although groundwater abstraction for domestic uses has decreased considerably during the past decade, abstraction for industrial purposes is still very high. In consequence, hydraulic heads have declined rapidly. They reach depths below 60 m below m.s.1. in the most heavily pumped aquifer horizons, which are between 150 and 250 m below m.s.1. Land subsidence has reached almost 2 m at some places, causing flooding and damage to buildings. A network of benchmarks and observation wells has been set up since the late 1970s to monitor land subsidence and groundwater levels. Land subsidence maps derived from leveling measurements at benchmarks show precise results for each observation point, but are inaccurate for the areas between the benchmarks of the investigation area. Interferometric SAR was tested to determine whether it can be used to supplement leveling owing to its higher accuracy in terms of the areal distribution of subsidence rates. It could be demonstrated that interferometric SAR can contribute to making monitoring of land subsidence more accurate than when only leveling at benchmarks stations is used.

Surface Subsidence and its Countermeasures in Cangzhou City

Abstract: A serious land surface subsidence occurred in Cangzhou City, Hebei Province. In the subsiding center of Cangzhou City, the land surface had sunk for 30 years by 2001 and the subsidence amount reached more than 2 m, which caused waterlogging of some segments in the city. And the subsidence in the river bed will seriously influence the security of the Water Transfering Project From South to North China. Our investigation indicates that the surface subsidence is mainly caused by over pumping groundwater.The thick-bedded clay layer is under the city, which provides the material for the land subsidence, under the big pressure, if the clay gives out the water in it, that means the land surface cannot be rebound. According to the analysis between cumulative subsidence and the groundwater table depth, the relative expression is established. The warning water table depth (critical va-lue) is 40 m and limited depth (stop pumping) is 70 m, and the trend of the land surface subsidence is forecasted. The countmeasure for land subsidence to control groundwater table is proposed too.

Application of ANSYS software to numerical simulation of coal mining

Abstract: Taking the typical coal mines such as Huafeng of Shandong, Wulong of Fuxin and Datai of Beijing of examples, the surface subsidence induced by coal mining, the dangerous regions determination of rockburst and the parameters optimization of oblique sublevel concentration mining were numerically simulated by using ANSYS software. According to the geology and coal reserves, the two-dimensional and three-dimensional models were established. The surface subsidence curves and the max subsidence values position were calculated for Huafeng mine. The results show that the subsidence displacements and influenced scopes increase with coal mining. The position of the max subsidence displacements gradually moves toward the mining direction. When 800m were mined, the max subsidence velocity 3.5mm/d appeared. The max subsidence displacements are 3.7m. In the 311 working face of Wulong mine, when 100m were mined the rockburst was easy to happen as the igneous rock wall effect. When 400m were mined the rockburst was also easy to happen as the roof failure induced by the stress concentration regions breakthrough. In the oblique sublevel concentration mining, only coal seam obliquities are 60o-67o, the mining distances have obvious effect on the max normal pressure stress of roof. The rules of normal displacements of roof and floor are that top displacements are greater than middle displacements, and middle displacements are greater than lower displacements. When the coal seam obliquity was 70o, the influenced scope of the advanced support pressure in the working face was 30m, and the scope of lower laneway was 25m. When three laneways are mined the peak position of advanced support pressure is 5.3m. The simulation results show the numerical analysis is reasonable with the practice. The ANSYS software is an effective way to coal mining.

Integrated GIS solution to mining subsidence assistant decision in mining area

Abstract: Mining subsidence brings enormous damages in mining area. Facing this problem, the paper proposes a solution based on integrated GIS. It takes the coal mining, terrain motion, subsidence predication, surface destruction and disaster evaluation as a whole integrated system. The solution provides an assistant decision support for mining subsidence's prevention and curing by means of classic probability integral model and GIS components model. Based on the research and analysis, a mining subsidence predication & assistant decision support system (abbreviated as MSPADSS) is developed using oriented object programming and component GIS development technology. MSPADSS is composed of five modules, i.e., data collection, mining subsidence predication, GIS graphic and attribute information management, surface subsidence damage evaluation and GIS spatial analysis & thematic mapping. All these are integrated in a whole system. Several recognitions and conclusions can be acquired through the research as follows: Firstly, prevention and curing of mining subsidence should consider many relative factors, which cover features from the bottom of the mine to the ground. Secondly, the subsidence prediction and damage evolution can be calculated and visualized synchronously by means of ComGIS developing. Thirdly, application of MSPADSS in the east of China shows that this integrated GIS solution is feasible and adoptable.

Environmental Problems and Its Prevention Countermeasures of Underground Water in South of Huanghe Delta

Abstract: Due to over-exploration of underground water, some environmental problems as lack of underground water, salt water intrusion, surface subsidence and earth crack have been occurred in south of Huanghe delta area, which should be soluted by underground water pondage and pollution prevention.

Stability evaluation of constructing large-scale building-toft above mine goaf

Abstract: The problems of stability of surface movement and deformation as time goes on and residual distortion are always important aspect of mining cover-rock subsidence study.This paper analyzes the time course of mining surface movement and deformation; and discusses the perdurability of surface subsidence and expected method of surface residual subsidence; and raises toft-stability evaluation index of constructing large-scale buildings above mine goaf; and puts forward the corresponding technological measures about building construction above mine goaf.

GROUND WATER RESOURCE ASSESSMENT UNDER THE CONDITIONS TO CONTROL GROUND SUBSIDENCE——A Case Study in Shanghai city

Abstract: Taking the sediment of the Quaternary system above the 5th confined aquifer, 350m under the ground around Shanghai city, as the target body to be studied as whole system for groundwater. A series of environmental geologic problems occurred, including ground subsidence, water table falling and exploitation condition degradation, as the results of the changed energy of the inner matter lead by groundwater pumping. Hydrogeological and engineering geological model is constructed after strict studies on the sediments of the Quaternary system in Shanghai region and its hydrogeological and engineering geological conditions. Furthermore, a 3-D water flow and one dimensional settlement model is established under the condition of maximum aquifer yield, reasonable water level lowering and ground surface subsidence, as well as a better economical and social benefit. This study also presents a method of groundwater resources assessment and management for big cities, especially those with water exploitation-induced ground subsidence problems.

Comprehensive Analysis of Safe Mining Underneath the Xitian River at Lingxin Coal Mine of China

Abstract: In order to study the damage of overburden rock and the surface subsidence caused by water-control mining at Lingxin Coal Mine, the in-situ stress distribution law, the damage height and crack height, the overburden rock displacement law and the ground pressure law were abtained by means of engineering geological investigation, color bore-bole TV inspecting, leakage monitoring in drilling fluid, simulation experiment, numerical computing, in-situ stress measurement and subsidence measurement. The result shows that safe mining at L3414 working face underneath the Xitian River and environmental protection can be implemented ultimately.

Inquiring into the influence of shallow groundwater exploitation on land subsidence in Suzhou,Wuxi and Changzhou area

Abstract: In Suzhou,Wuxi and Changzhou area,the land subsidence caused by the excess extraction of deep groundwater has become a serious hazardTherefore the provincial government has made a decision that the extraction of deep groundwater in this area is completely prohibited from 2000 to 2005In order to supply adequate water resources,many experts and scholars have suggested exploiting the shallow groundwaterHowever,the focus of the present dispute is whether the shallow groundwater exploitation will cause the same land subsidence problem as the deep groundwater didIn this paper,the hydro-geological condition,present situation of the land subsidence and the influence factors of the land subsidence are discussed in detailThe paper also analyzes and compares the differences of the descent volume of shallow groundwater and deep groundwater in the process of the extractionIt is concluded that the reasonable extraction of shallow groundwater can't cause the serious problem of the land subsidence

Study and application of the green mining technology

Abstract: This article clarifies the putting forward, connotation and greening technical system of mining The main content of the green technique in coal mining should includes water preserving mining, coal mining under building and bed separation grouting to reduce surface subsidence, partial extraction and backfill mining, simultaneous extraction of coal and coal-bed methane, coal roadway supporting and underground discharge of partial rock refuse, underground coal gasification, etc The theory of key strata in ground control provide a theory foundation for the green mining technology research

Rheological model of Dynamic Prediction on Mining Subsidence and Its Applications

Abstract: Based on the study of the movement and deformation regulation on overburden strata of the mining field, a time-displacement function of surface subsidence is provided in light of rheology; and by using the method of regression analysis, this paper gives out an empirical formula of dynamic surface subsidence suited to Datong mining area, the calculated results are fitted well with the actual measurement. Besides, the authors put forwards the index of the retardation time for the surface subsidence firstly, which can be used as numerical indicator for mining subsidence areas.

Analysis on Destructive Effect of Land Subsidence on Urban Sustainable Development

Abstract: As a geological disaster, land subsidence is discussed from the aspect of urban sustainable development. The various destructive effect of land subsidence for urban sustainable development, such as the impact on the human environment and the safety of building, induction of the hindered of drainage, the invasion of tile on coastal urban, and the restriction on the development of economy are presented. The preventing measures are suggested, which give the reference for the sustainable development of urban.

Numerical Simulation of Land Subsidence Effect Induced by Metro Tunnel Excavation and Water Loss

Abstract: Considering the case of Shenzhen metro Dajuyuan-Kexuanguan section tunnel excavation and the loss of water, in accordance with the effective stress analysis, sets up a flexible and plastic seepage flow-stress (coupling) analysis model. Uses VOF to trace the dynamic free water level of the unstable seepage field. Develops the corresponding numerical simulation analysis program. Emulates the process of dynamic excavation and the process of losing water in real tunneling work. Analyzes in detail the unstable seeping flow field in the process of losing water. And obtains the dynamic ground surface subsidence curve. It concludes that the calculation agrees with the field measurement.

Ground Subsidence in Areas of Loose Porous Aquifers

Abstract: Groundwater is one of the important water resources in northern China's plain areas. Many severe geological hazards have occurred in these areas due to ground subsidence which is caused by over exploitation of groundwater. This paper introduces and analyses the ground subsidence caused by groundwater exploitation and its mechanism in the northern China's plains. A ground subsidence prediction model has been developed based on the consolidation theory. The authors have tested this model in a case study of Fuyang City, Anhui Province, where ground subsidence is a severe environmental problem. In the case study, the model results match very well with those of the actual measurement. Two schemes of groundwater exploitation are assessed. The conclusion from the study could be used in the long-term water and economical management planning. The strategies for the control of ground subsidence are discussed.

Problems of Environmental Geology on the Urbanization in Tianjin City

Abstract: With the acceleration of economic development in Tianjin, the problems of urban environmental geology become more and more serious. There are 4 080.48 km~2 land subsiding more than (1 000) mm because of the groundwater over pumping. And several subsiding centers have been formed already. The ground subsidence lost the elevation, and it let the flood discharge more difficult, resu-lted in water accumulating after heavy rain. It decreased the seashore preventing the storm surge, and also damaged the pipe net under the city. The waste water irrigation, industy drainage and oil exploitation etc. made the soil and groundwater polluted, directly damaged the health of the people. The agriculture developing and the city construction speeded up the marsh shrinking, made the marsh ecological environment deterioration. The environment geological problems above mentioned will restrict Tianjin socio-economical development. So the author put forward some suggestions to avoid and reduce these hazards.

Assessment of Sinkhole Occurrences Using Fuzzy Reasoning Techniques

Abstract: Underground mining causes surface subsidence long after the mining operation had been ceased. Surface subsidence can be in the form of saucer-shaped depression or collapsed chimneys or sinkholes. Sinkhole formations are predominant over shallow-depth room and pillar mines having weak overburden strata. In this study, occurrences of sinkholes due to mining activity are assessed based on local geological conditions and mining parameters using fuzzy reasoning techniques. All input and output parameters are represented with linguistic hedges. Numerous fuzzy rules are developed to relate sinkhole occurrences with input parameters using fuzzy relational matrix. Based on the combined fuzzy rules, possibility of sinkhole occurrences can be ascertained once the geological and mining parameters of any area are known.