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1.
Morphometric analysis of sinkholes in a karst coastal area of southern Apulia (Italy) 总被引：1，自引：1，他引：0
Salento, the southern portion of Apulia region (SE Italy), is a narrow and elongated peninsula in carbonate rocks, with prevailing low coastlines, locally interrupted by high rock cliffs. The long stretches of low coasts are marked by typical karst landforms consisting of collapse sinkholes. As observed in many other karst coastal settings worldwide, development of sinkholes may be particularly severe along the coasts, where both natural and anthropogenic processes contribute to accelerate the dissolution of carbonate rocks and subsidence processes, even influencing the coastline evolution. Following a previous study, where the main features of sinkholes at Torre Castiglione (Taranto province) were investigated and described, and a preliminary susceptibility map produced, at the light of updated data and elaborations in the present paper we perform a detailed morphometric analysis on the sample of identified sinkholes. The main morphometric parameters generally used for sinkhole characterization have been considered in this study: shape of the sinkhole, azimuth and length of maximum and minimum axes, depth, elongation ratio, and distance from the shorelines. Each of them is described, both as individual parameter and in conjunction with the others, in the attempt to identify the main factors controlling development of sinkholes in the area, and their evolution as well. With regard to this latter aspect, beside simple morphometry of the sample of sinkholes at Torre Castiglione, we also focused our attention on the likely relationships existing between distribution and shape of the sinkholes and the tectonic discontinuities. To investigate the matter, a three-stage analysis has been carried out in this study by means of: field measurements of the fractures bounding the sinkholes, field measurement of the long axes azimuth of the elongated sinkholes, comparison of the previously described sets with the strikes of the main regional geological structures. The obtained results show, in addition to the coincidence of the main regional discontinuity systems with the major axis of elongated sinkholes, a clear control exerted by development and evolution of the sinkholes on the formation of coastal inlets and bays. Eventually, the approach here presented may be applied in other karst coastal sinkhole-prone areas, to gain new knowledge on the genesis and evolution of coastal sinkholes, and to properly evaluate the hazard they pose to the anthropogenic environment. 相似文献
2.
Quantitative sinkhole hazard assessments in karst areas allow calculation of the potential sinkhole risk and the performance
of cost-benefit analyses. These estimations are of practical interest for planning, engineering, and insurance purposes. The
sinkhole hazard assessments should include two components: the probability of occurrence of sinkholes (sinkholes/km2 year) and the severity of the sinkholes, which mainly refers to the subsidence mechanisms (progressive passive bending or
catastrophic collapse) and the size of the sinkholes at the time of formation; a critical engineering design parameter. This
requires the compilation of an exhaustive database on recent sinkholes, including information on the: (1) location, (2) chronology
(precise date or age range), (3) size, and (4) subsidence mechanisms and rate. This work presents a hazard assessment from
an alluvial evaporite karst area (0.81 km2) located in the periphery of the city of Zaragoza (Ebro River valley, NE Spain). Five sinkholes and four locations with features
attributable to karstic subsidence where identified in an initial investigation phase providing a preliminary probability
of occurrence of 0.14 sinkholes/km2 year (11.34% in annual probability). A trenching program conducted in a subsequent investigation phase allowed us to rule
out the four probable sinkholes, reducing the probability of occurrence to 0.079 sinkholes/km2 year (6.4% in annual probability). The information on the severity indicates that collapse sinkholes 10–15 m in diameter
may occur in the area. A detailed study of the deposits and deformational structures exposed by trenching in one of the sinkholes
allowed us to infer a modern collapse sinkhole approximately 12 m in diameter and with a vertical throw of 8 m. This collapse
structure is superimposed on a subsidence sinkhole around 80 m across that records at least 1.7 m of synsedimentary subsidence.
Trenching, in combination with dating techniques, is proposed as a useful methodology to elucidate the origin of depressions
with uncertain diagnosis and to gather practical information with predictive utility about particular sinkholes in alluvial
karst settings: precise location, subsidence mechanisms and magnitude, and timing and rate of the subsidence episodes. 相似文献
3.
骔岭集镇—大箐脚一带危岩为喀斯特地区典型的缓倾层状危岩,由于自然环境脆弱,在受岩溶地质、人工活动、降雨诱发等多种因素作用下形成,具有单体规模大、带状长度大、崩落距离远、影响人数多之特点。基于危岩的稳定性及危害分析的基础上,划分危岩崩塌严重影响区及监测预警避让区,对喀斯特地区典型的缓倾层状危岩地质灾害隐患点的早期识别与防范,提高防灾减灾工作的认识具有理论与现实的意义。 相似文献
4.
A genetic classification of sinkholes illustrated from evaporite paleokarst exposures in Spain 总被引：2，自引：0，他引：2
This contribution analyses the processes involved in the generation of sinkholes from the study of paleokarst features exposed
in four Spanish Tertiary basins. Bedrock strata are subhorizontal evaporites, and in three of the basins they include halite
and glauberite in the subsurface. Our studies suggest that formation of dolines in these areas results from a wider range
of subsidence processes than those included in the most recently published sinkhole classifications; a new genetic classification
of sinkholes applicable to both carbonate and evaporite karst areas is thus proposed. With the exception of solution dolines,
it defines the main sinkhole types by use of two terms that refer to the material affected by downward gravitational movements
(cover, bedrock or caprock) and the main type of process involved (collapse, suffosion or sagging). Sinkholes that result
from the combination of several subsidence processes and affect more than one type of material are described by combinations
of the different terms with the dominant material or process followed by the secondary one (e.g. bedrock sagging and collapse
sinkhole). The mechanism of collapse includes any brittle gravitational deformation of cover and bedrock material, such as
upward stoping of cavities by roof failure, development of well-defined failure planes and rock brecciation. Suffosion is
the downward migration of cover deposits through dissolutional conduits accompanied with ductile settling. Sagging is the
ductile flexure of sediments caused by differential corrosional lowering of the rockhead or interstratal karstification of
the soluble bedrock. The paleokarsts we analysed suggest that the sagging mechanism (not included in previous genetic classifications)
plays an important role in the generation of sinkholes in evaporites. Moreover, collapse processes are more significant in
extent and rate in areas underlain by evaporites than in carbonate karst, primarily due to the greater solubility of the evaporites
and the lower mechanical strength and ductile rheology of gypsum and salt rocks. 相似文献
5.
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
6.
7.
The formation of sinkholes in karst mining areas in China and some methods of prevention 总被引：2，自引：0，他引：2
Zhou Wanfang 《Environmental Geology》1997,31(1-2):50-58
Mining of coal, lead and zinc, gold, and iron ore deposits in karst areas has been closely associated with sinkholes in China.
Surface collapse causes an increase in mine water drainage and the possibility of major water inflow from karst aquifers,
which threatens the environment in mining areas and endangers mine safety. The origin of such sinkholes is analyzed quantitatively
in this paper and a combination of factors including soil weight, buoyancy, suffosion process and vacuum suction can contribute
to surface subsidence. The key measures to prevent sinkholes in mining areas are to control the amount of mine drainage, reduce
water-level fluctuation, seal off karst conduits and subsurface cavities in the overlying soil, prevent water inflow, and
to increase gas pressure in the karst conduits.
Received: 2 May 1996 · Accepted: 29 July 1996 相似文献
8.
J.P. Galve J. Bonachea J. Remondo F. Gutirrez J. Guerrero P. Lucha A. Cendrero M. Gutirrez J.A. Snchez 《Engineering Geology》2008,99(3-4):185
A preliminary sinkhole susceptibility analysis has been carried out in a stretch 50 km2 in area of the Ebro valley alluvial evaporite karst (NE Spain). A spatial database consisting of a sinkhole layer and 27 thematic layers related to causal factors was constructed and implemented in a GIS. Three types of sinkholes were differentiated on the basis of their markedly different morphometry and geomorphic distribution: large subsidence depressions (24), large collapse sinkholes (23), and small cover-collapse sinkholes (447). The susceptibility models were produced analysing the statistical relationships between the mapped sinkholes and a set of conditioning factors using the Favourability Functions approach. The statistical analyses indicate that the best models are obtained with 6 conditioning factors out of the 27 available ones and that different factors and processes are involved in the generation of each type of sinkhole. The validation of two models by means of a random-split strategy shows that reasonably good predictions on the spatial distribution of future dolines may be produced with this approach; around 75% of the sinkholes of the validation sample occur on the 10% of the pixels with the highest susceptibility and about 45% of the area can be considered as safe. 相似文献
9.
文章总结泰安市城区—旧县水源地内岩溶塌陷的发生发展历程，综合前人研究成果及最新的野外调查统计结果，对影响研究区岩溶塌陷的分布及影响因素进行了剖析，探明了岩溶塌陷的发育条件及诱发因素。结果表明:(1)研究区内岩溶塌陷主要发生在岩溶发育较强、断裂带附近、土层厚度小于30 m的区域；发生塌陷区域的土层结构以二元结构为主，其次是多元结构；塌陷大多发生在汛期，尤其是在大型降雨之后；(2)强烈的地下水开采活动引发的岩溶水大幅度波动是塌陷发生的最主要诱发因素，且岩溶地下水位在基岩面附近波动时最易引发塌陷；外界对土体的扰动也对塌陷有一定的影响，泰安城区旧镇铁路交汇处的塌陷与列车行车震动有密不可分的联系。综合分析以往岩溶塌陷的研究方向和程度，建议今后的研究重点应为塌陷过程演化监测与模拟、塌陷预警预报方法探索及数据库建设。 相似文献
10.
综合运用跨孔地震CT、探地雷达、高密度电阻率法、浅层地震反射波、土壤氡浓度和波速测试6种物探方法,对广州市白云区金沙洲岩溶地面塌陷、地面沉降地质灾害进行探测,查明了该区的溶洞、土洞及构造破碎带的分布。介绍了各种方法技术,对综合物探成果进行总结,结合实例说明综合物探方法在该区的应用取得了显著效果,为地质灾害防治提供了基础地质资料。在广花盆地岩溶发育区,首次应用跨孔地震CT探测建筑物地下岩溶分布,为评价受岩溶地质灾害影响的建筑物安全提供依据。 相似文献
11.
高密度电法在柳州太阳村镇岩溶塌陷区调查中的应用研究 总被引：1，自引：0，他引：1
为了查明柳州太阳村镇岩溶塌陷形成的地质背景,本文采用高密度电法对该塌陷区进行调查研究。研究结果表明:高密度电法对于确定土层的厚度,区分土层和岩石的分界面具有较好的效果,通过电阻率的分布及变化趋势,可以较好的圈定地下岩溶裂隙带的发育位置,结合地质资料,对识别断裂破碎带也有较好的效果。三个塌陷区的致塌地质背景不尽相同:第Ⅰ,Ⅲ塌陷区塌陷的形成与人类活动密切相关,分别由机井抽水及输油管道铺设引发;第Ⅱ塌陷区塌陷的形成与自然因素相关,由断裂破碎带触发。通过高密度电法反演结果断面图,能较准确地查明塌陷的潜伏隐患区:第Ⅰ塌陷区的隐伏区为通过抽水井的近东西向的岩溶裂隙带,第Ⅱ塌陷区地质灾害的潜伏区为断层西侧的岩溶裂隙带,第Ⅲ塌陷区的隐患区为输油管道附近东侧的岩溶裂隙带,均位于人类活动频繁附近地段及构造发育带。 相似文献
12.
基于层次分析法的城市岩溶塌陷危险性评价——以武汉市南部为例 总被引：3，自引：1，他引：2
文章依据武汉市岩溶塌陷形成机理及影响因素,选取岩溶发育程度、土层厚度、覆盖层结构、岩溶水水位波动幅度、抽水井影响、工程施工强度等6个评价因子,构建研究区岩溶塌陷危险性层次分析评价模型,对武汉市南部可溶岩分布区183个岩溶塌陷危险性评价单元进行岩溶塌陷危险性综合指数计算,绘制出了研究区岩溶塌陷危险性等级分区图。结果表明,高危险区有3个,主要集中在研究区西北侧青菱乡毛坦港、长征村-光霞村一带;中危险区有92个,主要为第四系中更新统黏土覆盖型岩溶区;低危险区有88个,包括部分覆盖型岩溶区以及所有埋藏型岩溶区。 相似文献
13.
Subsidence hazard avoidance based on geomorphological mapping in the Ebro River valley mantled evaporite karst terrain (NE Spain) 总被引：1，自引：6，他引：1
F. Gutiérrez-Santolalla M. Gutiérrez-Elorza C. Marín C. Maldonado P. L. Younger 《Environmental Geology》2005,48(3):370-383
In the valley of the Ebro River to the southeast of the city of Zaragoza (NE Spain), the dissolution of evaporite sediments (gypsum, halite and Na-sulphates) which underlie alluvial deposits gives rise to numerous sinkholes. These sinkholes are a potential hazard to human safety, particularly where they develop in a catastrophic way. Even slow-developing sinkholes are problematic, as they damage urban and agricultural infrastructure, necessitating costly repairs and vigilant maintenance. To assist in developing avoidance strategies for these hazards, the factors controlling sinkhole occurrence have been assessed using geomorphological maps produced from aerial photographs for 1956 and 1981. Important controls on sinkhole development are found to include underlying geological structure (manifest in preferred orientations of sinkholes on the azimuths N130-150E and N30-40E), and the presence of glauberite in the groundwater flow path, which apparently promotes accelerated gypsum dissolution. Perhaps surprisingly, alluvium thickness does not appear to significantly correlate with the density of sinkholes on the floodplain in this area. The maps for 1956 and 1981 reveal that both human activity and natural processes can serve to obscure the true density of sinkhole development. For instance, a large number of sinkholes which were conspicuous in 1956 have since been back-filled by farmers. In the most fluvially active zone of the Ebro valley (the meander belt), the relatively low density of sinkholes compared with adjoining zones suggests that subsidence is being masked by morpho-sedimentary dynamic processes (aggradation and erosion). Careful geomorphological mapping for different time periods yields a much more accurate impression of the frequency of sinkhole development than would be gained from surveying currently visible sinkholes in the area of interest. 相似文献
14.
山东省泰莱盆地岩溶塌陷发育特征及形成机理 总被引：12，自引：11，他引：1
泰莱盆地位于山东省中部,截止2013年底,盆地内共发生有记录岩溶塌陷97处,161点次,严重威胁人民生命财产安全。文章在总结前人研究基础上,结合最新调查、监测成果,研究了泰莱盆地岩溶塌陷的分布特征、地质结构模式及其形成机理。结果表明:盆地内岩溶塌陷点多集中分布于岩溶地下水降落漏斗及其影响范围内;塌陷点分布受构造控制明显;塌陷区第四系厚度一般小于30 m,下伏基岩主要为奥陶纪灰岩;80%以上的塌陷集中发生于汛期。根据岩溶塌陷点土层结构、地下水动力条件的不同,建立了3种岩溶塌陷的基本地质模式:单层、双层和多层结构土层岩溶塌陷,其中单层结构土层岩溶塌陷的形成历经“真空吸蚀-崩解剥落-塌陷”3个阶段;双层土层结构岩溶塌陷形成演化过程可概括为“渗透变形-崩解垮塌-塌陷”或“真空吸蚀-渗透变形-塌陷”3个阶段;多层结构土层岩溶塌陷历经“真空吸蚀-渗透变形-崩解垮塌-塌陷”4个阶段。 相似文献
15.
16.
广佛肇地区岩溶塌陷易发性分析 总被引：1，自引：1，他引：0
广州、佛山和肇庆市(广佛肇地区)作为经济发达地区,岩溶塌陷时有发生,给当地人民群众和经济发展带来较大威胁。依托区域地质调查成果,根据岩溶地质条件情况,选择岩溶塌陷分布特征、岩溶发育条件、覆盖层特征、地质构造、水文地质条件和土地利用类型6个因素,系统研究各个因素对岩溶塌陷形成的作用和各个因素之间的权重关系。在此基础上,运用地理信息系统技术和多元统计方法(层次分析法),建立岩溶塌陷发育的多因素判别模型,进而对广佛肇地区划分出高、中等和低易发区域,并根据岩溶塌陷易发区划,编制广佛肇地区重大基础设施岩溶塌陷易发区划应用图集,统计出重大基础设施所在易发区范围。 相似文献
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18.
广州市白云区岩溶塌陷风险初探 总被引：3，自引：0，他引：3
识别出广州白云区岩溶塌陷风险因素,构建岩溶塌陷层次递阶结构模型,运用层次分析法的相关原理计算出基本风险因素对岩溶塌陷风险事件的影响权重。定义极易塌陷区Ⅰ、易塌陷区Ⅱ、次易塌陷区Ⅲ、不易塌陷区Ⅳ和稳定区Ⅴ共5个岩溶塌陷等级分区,建立各基本风险因素5个等级与岩溶塌陷等级分区的对应关系。为实现岩溶塌陷风险的定量评价,定义单因素致塌概率pi,引入伯努利试验建立岩溶塌陷概率计算模型,选取覆盖层厚度、岩溶发育程度、地下水位埋深、基岩岩性、覆盖层结构与底板岩性、地下水开采强度、地下活动强度和地表施工加载与振动等8个基本风险因素参与评价单元塌陷概率计算,并据此确定岩溶塌陷风险等级狭义标准,为区域岩溶塌陷等级分区的划分提供参考依据。岩溶塌陷风险等级分区表明：极易塌陷区集中在分析区内的江村、古楼岗、泉溪、西湖、社岗一带;易塌陷区和次易塌陷区主要分布在江高镇和原石井镇等地带。风险等级分区与白云区已有岩溶塌陷历史统计资料及塌陷危害程度评价结果较为吻合,从而验证了评价方法的有效性。 相似文献
19.
F. Gutiérrez-Santolalla M. Gutiérrez-Elorza C. Marín G. Desir C. Maldonado 《Environmental Geology》2005,48(3):360-369
A highly active collapse sinkhole field in the evaporitic mantled karst of the Ebro river valley is studied (NE Spain). The subsidence is controlled by a NW-SE trending joint system and accelerated by the discharge of waste water from a nearby industrial state. The morphometry, spatial distribution and temporal evolution of the sinkholes have been analysed. The volume of the sinkholes yields a minimum estimate of average lowering of the surface by collapse subsidence of 46 cm. The clustering of the sinkholes and the tendency to form elongated uvalas and linear belts, in a NW–SE direction have a predictive utility and allow the establishment of criteria for a hazard zonation. With the precipitation record supplied by a pluviograph and periodic cartographic and photographic surveys the influence of heavy rainfall events on the triggering of collapses has been studied. 相似文献
20.