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1.
GIS and ANN coupling model: an innovative approach to evaluate vulnerability of karst water inrush in coalmines of north China 总被引:5,自引:0,他引:5
Evaporites, including rock salt (halite) and gypsum (or anhydrite), are the most soluble among common rocks; they dissolve
readily to form the same types of karst features that commonly are found in limestones and dolomites. Evaporites are present
in 32 of the 48 contiguous states in USA, and they underlie about 40% of the land area. Typical evaporite-karst features observed
in outcrops include sinkholes, caves, disappearing streams, and springs, whereas other evidence of active evaporite karst
includes surface-collapse structures and saline springs or saline plumes that result from salt dissolution. Many evaporites
also contain evidence of paleokarst, such as dissolution breccias, breccia pipes, slumped beds, and collapse structures. All
these natural karst phenomena can be sources of engineering or environmental problems. Dangerous sinkholes and caves can form
rapidly in evaporite rocks, or pre-existing karst features can be reactivated and open up (collapse) under certain hydrologic
conditions or when the land is put to new uses. Many karst features also propagate upward through overlying surficial deposits.
Human activities also have caused development of evaporite karst, primarily in salt deposits. Boreholes (petroleum tests or
solution-mining operations) or underground mines may enable unsaturated water to flow through or against salt deposits, either
intentionally or accidentally, thus allowing development of small to large dissolution cavities. If the dissolution cavity
is large enough and shallow enough, successive roof failures can cause land subsidence and/or catastrophic collapse. Evaporite
karst, natural and human-induced, is far more prevalent than is commonly believed. 相似文献
2.
我省岩溶充水矿床较为广泛,可分为岩溶充水和暗河管道充水矿床两个类型,前者包括水文地质条件简单、中等和复杂三个亚类。本文比较全面地阐述了它们的基本水文地质特征,并针对各类矿床由于开发普遍引起的岩溶塌陷问题,提出了岩溶水的防治与利用意见。 相似文献
3.
The aim of this study is to shed light on the hydrogeochemical characteristics of karst underground waters at shallow depth in Guiyang City, Guizhou Province with an emphasis on the geochemistry of major elements. Guiyang City bears abundant underground waters and it is also an important representative of the karst areas throughout the world. Ca^2 and Mg^2 are the dominant cations, accounting for 81% -99.7% of the total, and HCO3^- and SO4^2- are the dominant anions. Weathering of limestones and dolostones is the most important factor controlling the hydrogeochemistry of underground waters, and weathering of sulfate and evaporite rocks is less important. Moreover, the precipitation and human activities also have a definite influence on the hydrogeoehemistry of underground waters in the region studied. 相似文献
4.
南宁市是广西岩溶地面塌陷危害十分严重的城市之一。2012年6月2日突发的岩溶地面塌陷主要集中分布在坛洛镇南西方向,形成塌陷坑19个,地裂缝17条,威胁62户共232人,潜在经济损失约870万元。坛洛塌陷多形成于松散盖层厚度小于15 m,地下水位埋深小于20 m,地下岩溶强发育的区段。碳酸盐岩岩溶发育、松散盖层厚度较小和水动力条件(降水、地表水和地下水)复杂为岩溶塌陷产生的必要条件,尤以地下水的作用对岩溶塌陷的形成起至关重要的作用。通过对坛洛地下水动态观测与岩溶塌陷的调查研究确定地下水强径流带,分析评价岩溶地面塌陷的危险性,为岩溶地区的岩溶塌陷危险性勘察、评价工作提供一定指导意义。 相似文献
5.
Irena Pluta 《Environmental Geology》2001,40(3):345-348
Waters discharged from coal mines in the Upper Silesia in Poland cause contamination of rivers and their sediments. Saline
waters discharged from coal mines of the southern region contain elevated barium and radium. The discharge of these elements
can be reduced by treating these waters with sulphates in mine workings. Sources of sulphate used in treatments include gypsum,
anhydrite and industrial wastes such as: fly ash, slags and flotation tailings. Gypsum and anhydrite are used in the coal
mine workings as components of the fire protection walls. Industrial wastes from power plants are stored in the mine workings
as fire- and methane-protection agents. Sulphates precipitate barium and radium from saline waters inflowing into the mine
workings. The waters can be treated by flowing them through old mine workings. In this case, the source of sulphates is the
natural oxidation of pyrite. Mining activities and the natural process of desulphurisation of the Carboniferous rocks reduce
the amount of barium and radium that is discharged in the southern region of Upper Silesia. The processes for reducing the
environmental impact of toxic discharges from the mines should be monitored.
Received: 3 July 1997 · Accepted: 27 March 2000 相似文献
6.
冀北下寒武统馒头组底部有一套层位稳定的紫红色、灰黄色白云质砾岩和页岩。砾石具棱角状或次棱角状,粒度分选差,砾石成分与填隙物成分相同,主要为白云岩。根据对该层位岩石组成、沉积特征的分析,其成因与砾岩(碳酸盐岩)中盐类物质经次生变化形成溶塌角砾岩相关。由于该层位稳定,含盐类物质较高,因此在一定层位有可能找到石膏矿。 相似文献
7.
In the framework of a regional landslide susceptibility study in southern Sicily, a test has been carried out in the Tumarrano
river basin (about 80 km2) aimed at characterizing its landslide susceptibility conditions by exporting a “source model”, defined and trained inside
a limited (about 20 km2) representative sector (the “source area”). Also, the possibility of exploiting Google Earth™ software and photo-images databank to produce the landslide archives has been checked. The susceptibility model was defined,
according to a multivariate geostatistic approach based on the conditional analysis, using unique condition units (UCUs),
which were obtained by combining four selected controlling factors: outcropping lithology, steepness, plan curvature and topographic
wetness index. The prediction skill of the exported model, trained with 206 landslides, is compared with the one estimated
for the whole studied area, by using a complete landslide archive (703 landslides), to see to what extent the largest time/money
costs needed are accounted for. The investigated area stretches in the fore-deep sector of southern Sicily, where clayey rocks,
mainly referring to the Numidian Flysch and the Terravecchia Formations, largely crop out. The results of the study confirm
both the exploitability of Google Earth™ to produce landslide archive and possibility to adopt in assessing the landslide susceptibility for large basin, a strategy
based on the exportation of models trained in limited representative sectors. 相似文献
8.
Palaeo-karst collapse pillars in northern China and their damage to the geological environments 总被引:4,自引:0,他引:4
According to statistics, there are a total of 39 sites of palaeo-karst collapse pillars in Northern China, as well as 3,650
palaeo-karst collapse pillars. Through an overall survey and analysis of the distribution regularities and formation mechanisms
of palaeo-karst collapse pillars in the northern coal mine regions, this paper found that the rock formation structures, geological
structures, karst characters, underground hydrodynamic conditions of karst and neotectonic movement conditions are basic geological
bases for the formation of karst collapse pillars and rule the distribution of them. Karst collapse pillars apparently have
three south–north regularities in terms of distribution, and they have resulted in severe damages to geological resources
and environment in their distribution areas: mine water inrush causing and coal resources damage and influencing the impounding
of reservoirs as well as the stability of dam sites. Based on the basic geological features of palaeo-karst collapse pillars
in northern China, this paper also introduces the new methods of integrated prospecting of successive approximation to determine
hydraulic conductivity of palaeo-karst collapse pillars. 相似文献
9.
内蒙古伊盟地区现代碱湖地质特征和形成条件分析 总被引:1,自引:0,他引:1
内蒙古伊克昭盟地区分布着众多小型现代盐湖。湖内沉积有天然碱、芒硝和石盐等化工矿产。各碱湖地层构成碎屑-粘土-蒸发岩沉积旋回,沉积厚度在10m 左右,基岩为白垩纪砂岩。结晶碱层以块状、厚层状为主,其分布受湖盆形态控制,一般埋深0.1~0.4m。伊克昭盟地区碱湖的形成是构造活动的结果。经长期风化剥蚀,地表和地下水向古河道和风蚀洼地聚集了基岩或剥蚀区地层的有关组分,并携带到湖盆中,使湖水转变为成水、卤水,后来由于气候骤然变冷,湖水中 Na_2CO_3或 Na_2SO_4过饱和而分别结晶为Na_2CO_3·10H_2O 或 Na_2SO_4·10H_2O,从而形成碱湖沉积。 相似文献
10.
通过对松宜矿区地面塌陷调查研究,按煤层顶板埋深和塌陷成因的不同将其分为浅埋型采空塌陷和深埋型岩溶塌陷,前者系指煤层顶板为栖霞组、茅口组地层区域,在缓坡地带、构造、岩溶发育部位、煤层厚度大的采空区易形成采空塌陷,无序复采、矿柱遭受破坏是主要诱发因素;后者是在矿坑高强度疏排地下水导致地下水位大幅降低,形成以真空吸蚀为主要成因的岩溶塌陷。针对其成因机制,提出了防治建议,对矿区地质环境综合治理具有实际意义。 相似文献
11.
Environmental and engineering problems of karst Geology in China 总被引:1,自引:0,他引:1
Yuan Daoxian 《Environmental Geology》1988,12(2):79-87
Karst terrane is generally regarded as a fragile and vulnerable environment. Its underground drainage system can aggrevate
both drought and flood problems; the lack of filtration in an underground conduit makes waste disposal more difficult; and
the lack of soil cover in bare karstland can enhance deforestation. Moreover, karst terranes are quite often haunted by a
series of engineering problems, such as water gushing into mines or transportation tunnels; leakage from reservoirs; and failure
of building foundations. In China, there are more than 200 cases of karst collapse, which include many thousands of individual
collapse points. Some of these are paleo and natural collapses, but most of them are modern collapses induced by human activities
and they have caused serious damage. Many factors such as geologic structure, overburden thickness and character, lithologic
features of karstified rock, and intensity of karstification are related to development and distribution of modern collapses.
However, China's karst is mainly developed in pre-Triassic, old phase, hard, compact, carbonate rock. Consequently most modern
collapses have occurred only in the overlying soil. So it is understandable that the fluctuation of the water table in the
underlying karstified strata plays an important role in the process of collapse. Nevertheless, there are different explanations
as to how the groundwater activities can induce collapse. 相似文献
12.
贵州平寨水库左岸底层灌浆廊道大型充填溶洞及其形成机制 总被引:1,自引:0,他引:1
平寨水库坝址区以碳酸盐岩为主,岩溶较发育,水库左岸底层灌浆廊道大型充填溶洞,是水库地下工程施工开挖中揭露的规模最大、对水库渗漏影响最大、设计及施工处理难度最大的溶洞。本文以工程前期地质勘察工作为基础,在区域地貌、地质构造格局、地层岩性、地表及地下水系发育特征研究的基础上,结合工程防渗施工揭露的岩溶水文地质现象、洞穴充填物研究等,从可溶性岩层、地下水来源及运移途径、暗河冲刷与洞顶坍塌作用4个方面,对溶洞发育形成机制进行了研究。分析认为,鸡场背斜北西翼纵向张裂隙和横张裂隙及层间滑脱、断裂破碎带,为五里大洞鸡场洼地上坝洼地地下水向三岔河的径流提供了运移的原始空间与通道,形成溶洞的地下水为五里大洞鸡场洼地上坝洼地地下暗河,长期溶蚀作用使裂隙通道变为溶蚀宽缝并最终转化为岩溶管道,岩溶水沿此通道在左岸底层灌浆廊道桩号0+238~0+296m附近下中部岩体呈虹吸状循环,地下水的强烈冲刷与洞顶坍塌在溶洞形成过程中的作用巨大,后因深部径流条件改变,岩溶管道被逐渐堵塞,形成如今的大型充填溶洞。 相似文献
13.
Water from the Kombat mine was delivered to the Omatako dam via the 263-km-long Grootfontein-Omatako canal during test runs
in 1997. It is intended to supply water from Kombat and other underground mines in the Otavi Mountain Land to the capital
Windhoek. The Cu-Pb-Zn orebodies are hosted by carbonate rocks and the mine waters are supersaturated with respect to calcite
and CO2. Along the length of the canal, the CO2 partial pressure drops from 10−2.1 atm at the inlet of the Kombat mine to 10−3.5 atm at the end of the canal. This is accompanied by a drop in Ca concentration from about 60 to about 20 mg/l. The heavy
metal concentrations (Cd, Cu, Mn, Pb and Zn) drop along the course of the canal to values far below the national drinking-water
standard. Scavenging by calcium carbonate precipitation is the major depletion mechanism.
Received: 21 June 1999 · Accepted: 29 August 1999 相似文献
14.
Hydrochemical framework of the aquifer in and around East Kolkata Wetlands,West Bengal,India 总被引:1,自引:0,他引:1
The area lies between Hugli river in the northwest and Bidyadhari river in the east and includes the East Kolkata Wetlands.
The East Kolkata Wetlands is included in the List of Wetlands of International Importance (“Ramsar List”), as per the Convention
on Wetlands signed in Ramsar, Iran, in 1971. This wetland has been declared as a Ramsar site on the 19th August 2002 (Ramsar
site no. 1208) and therefore has acquired an international status. The area is a part of the lower deltaic plain of the Bhagirathi–Ganga
river system and is generally flat in nature. The sub-surface geology of the area is completely blanketed by the Quaternary
fluviatile sediments comprising a succession of clay, silty clay, sand and sand mixed with occasional gravel. The Quaternary
aquifer is sandwiched between two clay sequences. The confined aquifer is made up of moderately well sorted sand and reflects
fluviatile environment of deposition. The regional groundwater flow direction is from east to west. Detailed geochemical investigations
of 40 groundwater samples along with statistical analysis (for example, correlation and principal component analysis) on these
chemical data reveal: (i) four types of groundwater quality, for example, good, poor, very poor and water unsuitable for drinking
purpose, (ii) four hydrochemical facies which may be assigned to three broad types such as “fresh”, “blended”, and “brackish”
waters, (iii) the evolution of the “blended” water is possibly due to hydraulic mixing of “fresh” and “brackish” waters within
the aquifer matrix and/or in well mixing, and (iv) absence of Na–Cl facies indicates continuous flushing of the aquifer. 相似文献
15.
《Environmental Earth Sciences》2012,65(3):805-812
Karst topography is a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually limestone and evaporites.
Karstification in the Sivas basin (Turkey) has sculpted a beautiful landscape with a distinctive beauty and appeal for both
local inhabitants and visitors. Dolines are very special geological landscape features found in karst regions, and the Sivas
basin has several giant dolines amongst its thousands of smaller dolines. The basin constitutes a distinctive karst architecture
with a system of collapse and/or dolines and caves. Anyone who walks along the shores of a lake resulting from the collapse,
in this gypsum terrain, will be amazed with the lake and rocks that surround them. In this paper, dolines in the gypsum terrain
are evaluated and discussed according to their value as a “Geological Heritage”. Three main characteristics of dolines, namely
their scientific, aesthetic and ecosystem importance are considered and discussed. Dolines and karstified areas as representative
examples of landform types possess the three attributes for them to be considered as a Geological Heritage in that they demonstrate
the effect of erosion on the landform, geomorphic processes that are still active and a range of features characteristic of
the rock unit involved. 相似文献
16.
N. A. Gnatus’ M. D. Khutorskoy V. K. Khmelevskoi 《Moscow University Geology Bulletin》2011,66(3):151-157
The geological-geophysical, methological, and economic aspects of extraction and utilization of petrothermal resources (“hot
dry rock thermal”) for thermal and electric energy production were considered. Heat collectors are hydraulic fracturing zones
of natural or artificially made cracks in the crystalline rocks of the basement; these rocks have higher temperature and can
be a kind of “thermal cauldron.” Detection of such “collectors” can be carried out by geophysical methods. When pumped out
of wells and warmed to 100–300°C, waters function as a heat transfer for thermal energy supply and electric energy generation.
If the technical problem of the rapid drilling of 6–10 km wells could be solved, then petrothermal energy will become competitive
with the traditional types of energy production and supply. 相似文献
17.
Numerous archaeological sites dating to the greek-roman period have been found in the underground of the city of Catania (eastern
Sicily, Italy). Their presence is a testimony of the several settlements that have followed in this area over time. In this
work we have conducted electromagnetic surveys, consisting of ten georadar profiles, inside the church of “S. Agata alla Badia”,
damaged during the earthquake occurred in eastern Sicily on 13 December 1990. The aim was to investigate the area where the
church is located to obtain information useful for its structural recovery. Mechanical drillings were also carried out to
reconstruct the local stratigraphy, which could be complicated by the presence of underground cavities and artefacts, as evidenced
by recent excavations beneath the Catania Cathedral, in the nearby Piazza Duomo. From the interpretation of the GPR data,
the presence of ancient masonry structures underlying the recent foundations was highlighted. In addition, the GPR survey
allowed us to identify and locate reflective horizons in the subsurface, probably due to the presence of materials with different
state of aggregation and/or to buried structures. 相似文献
18.
Analysis of Cracking in Rock Salt 总被引:4,自引:0,他引:4
Summary ?The use of underground mines in salt-rock formations for waste repositories makes the precise analysis of isolation properties
of rock salt very important. One of the main mechanisms responsible for a degradation of isolation ability of the rock salt
is the generation and development of cracks under influence of mining processes. Various aspects of cracking in salt rocks
are studied – both in situ and in laboratory tests – for rocks of the world's largest Verkhnekamskoe potash-ore deposit (Russia). It is shown that not
all the discontinuities (fractures) are closed in the course of the creep deformation of rocks. Parameters of cracking are
determined for various conditions: age of pillars, mining technology, etc. Different methods – filtration, electrometric,
nuclear magnetic resonance, mechanical tests – are used for crack observation and characterisation, both in specimens and
in situ. Traditional investigations (partly with specially designed equipment) are accomplished by the testing methods of fracture
mechanics for determination of critical values of stress intensity factors K
Ic and K
IIc. The problems and ways of the use of the obtained results in analysis of isolation properties for areas in vicinity of underground
mines and/or waste repositories are discussed. 相似文献
19.
The current status of mapping karst areas and availability of public sinkhole-risk resources in karst terrains of the United States 总被引:2,自引:0,他引:2
Subsidence from sinkhole collapse is a common occurrence in areas underlain by water-soluble rocks such as carbonate and evaporite rocks, typical of karst terrain. Almost all 50 States within the United States (excluding Delaware and Rhode Island) have karst areas, with sinkhole damage highest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. A conservative estimate of losses to all types of ground subsidence was $125 million per year in 1997. This estimate may now be low, as review of cost reports from the last 15 years indicates that the cost of karst collapses in the United States averages more than $300 million per year. Knowing when a catastrophic event will occur is not possible; however, understanding where such occurrences are likely is possible. The US Geological Survey has developed and maintains national-scale maps of karst areas and areas prone to sinkhole formation. Several States provide additional resources for their citizens; Alabama, Colorado, Florida, Indiana, Iowa, Kentucky, Minnesota, Missouri, Ohio, and Pennsylvania maintain databases of sinkholes or karst features, with Florida, Kentucky, Missouri, and Ohio providing sinkhole reporting mechanisms for the public. 相似文献
20.