M.Tech. (Extraction Metallurgy) / The discovery of gold at Langlaagte in 1886 led to the development of gold mining in the Far West Rand in 1934. When shafts were sunk, water from the dolomites posed a serious threat to mining. Despite cementation that sealed the many fissures, water still found its way into the underground workings. This led to the “uniform” policy of dewatering. The farming communities in the area that were dependent on the ground water had to be considered, as they had lost their livelihood. As the water levels lowered, dolines and sinkholes were formed, posing a serious threat to life and property. When the mines eventually cease to operate, be it due to high working costs, or the declining grade of the ore body, the re-watering of the dolomitic compartments will occur as a natural consequence. When water comes to within six metres of the original water level, ground instability, the formation of dolines and sinkholes, both new and existing, will occur, threatening the important rail link between Pretoria and Cape Town as it passes through Far West Rand, as well as the N12 between Johannesburg and Potchefstroom, as well as the N14 which lies to the east connecting the Gauteng Province and the North West Province. The dewatering of the compartments caused the soil which formed the roof of the cavities to dry. Re-watering will cause this dry, stable material to become wet and unstable. Where mixtures of slime and/or other material, which is not part of the geological composition of that area was used, the same phenomenon will apply. A further complication is caused by the slimes dams which are unlined. In fact, some of the slime dams were deliberately constructed over cavernous dolomite. This large mass of mine tailings over the dolomitic aquifers will “liquefy”. If the re-watering is not carefully managed the rising water table will undoubtedly trigger a rash of new sinkholes, with catastrophic consequences for unsuspecting communities that may have been established in sensitive areas. The results of previous investigations by the Departments Minerals, Energy and Water Affairs who, due to the loss of institutional memory, might not be able to find the relevant information. Other organizations such as the Council for Geoscience could be using the results for consultancy. The information should be digitized and be available to the broader South African public. FWRDWA is currently in charge of monitoring events in the area. Levelling observations have been carried out quarterly and, so far the movement of ground is minimal. The potential hazard of ground instability will recur with the re-watering of the dolomitic compartments of the Far West Rand. To support what could happen, reference is made to events which took place in the late seventies when the Far West Rand had an above average rainfall. The Donaldson Dam overflowed into the Wonderfontein Spruit and into the dewatered Venterspost compartment. As a result, the water level of the Venterspost Compartment rose rapidly which led to the re-activation of sinkholes and the formation of new ones in the Venterspost area. In the present work levelling has been carried out along most of the loops affected and the results of the levelling give an impression that the surface is currently relatively stable. This Dissertation is presented as an attempt to alert the authorities to the potential dangers if the post mining period is not carefully monitored and insufficient provision made to deal with potential contingencies.

Dams that comprise broadly and widely graded glacial materials, such as moraines, have been found to be susceptible to internal erosion, perhaps more than dams of other soil types. Internal erosion washes out fine-grained particles from the filling material; the erosion occurs within the material itself or at an interface to another dam zone, depending on the mode of initiation. Whether or not internal erosion proceeds depend on the adequacy of the filter material. If internal erosion is allowed, it may manifest itself as sinkholes on the crest, increased leakage and muddy seepage once it surfaces, which here is called surfacing internal erosion (i.e. internal erosion in the excessive erosion or continuation phase). In spite of significant developments since the 1980s in the field of internal erosion assessment, the validity of methods developed by others on broadly graded materials are still less clear because most available criteria are based on tests of narrowly graded granular soils. This thesis specifically addresses dams that are composed of broadly graded glacial soils and investigates typical indicators, signs and behaviors of internal erosion prone dams. Based on a review of 90+ existing moraine core dams, which are located mainly in Scandinavia as well as North America and Australia/New Zealand, this thesis will show that not only the filter’s coarseness needs to be reviewed when assessing the potential for internal erosion to surface (i.e., erosion in the excessive or continuing phase); in addition, the grading stability of the filter and the core material as well as non-homogeneities that are caused by filter segregation need to be studied. Cross-referencing between these aspects improves the assessment of potential for internal erosion in dams of broadly graded soils and furthermore it provides aid-to-judgment. / QC 20100715

No description available.

Improving Sinkhole Mapping Using LiDAR Data and Assessing Road Infrastructure at Risk in Johnson City, TN. Kingsley Fasesin1, Dr. Ingrid Luffman 1, Dr. Eileen Ernenwein 1 and Dr. Arpita Nandi1 1 Department of Geosciences, College of Arts and Sciences, East Tennessee State University, Johnson City, TN; Abstract Predicting infrastructure damage and economic impact of sinkholes along roadways requires mapping of sinkhole distribution and development of a model to predict future occurrences with high accuracy. The study is carried out to define the distribution of sinkholes in Johnson City, TN and risks they pose to roads in the city. The study made use of a 2.5 ft Digital Elevation Model (DEM) derived from Light Detection and Ranging (LiDAR) data acquired from Tennessee Geospatial clearing house (TNGIS) and an inventory of known sinkholes identified from topographic maps. Depressions were identified using the LiDAR-derived DEM by subtracting a filled-depressions DEM from the original study area DEM. Using a spatial join, mapped sinkholes were matched to depression polygons identified from the LiDAR-derived DEM. For all matched sinkhole-polygon pairs, three indices were calculated: circularity index, area ratio of minimum bounding rectangle, and proximity to train tracks and roads. The dataset was partitioned into training (70%) and validation (30%) subsets, and using the training dataset, thresholds for each index were selected using typical values for known sinkholes. These rules were calibrated using the 30% validation subset, and applied as filters to the remaining unmatched depression polygons to identify likely sinkholes. A portion of these suspected sinkholes were field checked. The future direction of this research is to generate a sinkhole formation model for the study area by examining the relationship between the mapped sinkhole distribution, and previously identified sinkhole formation risk factors. These factors include: proximity to fault lines, groundwater and streams; depth to bedrock; and soil and land cover type. Spatial Logistic Regression analysis will be used for model development, and results will be used to generate a sinkhole susceptibility map which will be overlain on the road network to identify the portions of interstate and state highways at risk of sinkhole destruction.

Made available in DSpace on 2015-02-24T19:48:43Z (GMT). No. of bitstreams: 1 PedroXN_ate_cap4.pdf: 4119464 bytes, checksum: afcae765da030e3171f973a2422290fb (MD5) Previous issue date: 2006-05-05 / In Fazenda Bel?m oil field (Potiguar Basin, Cear? State, Brazil) occur frequently sinkholes and sudden terrain collapses associated to an unconsolidated sedimentary cap covering the Janda?ra karst. This research was carried out in order to understand the mechanisms of generation of these collapses. The main tool used was Ground Penetrating Radar (GPR). This work is developed twofold: one aspect concerns methodology improvements in GPR data processing whilst another aspect concerns the geological study of the Janda?ra karst. This second aspect was strongly supported both by the analysis of outcropping karst structures (in another regions of Potiguar Basin) and by the interpretation of radargrams from the subsurface karst in Fazenda Bel?m. It was designed and tested an adequate flux to process GPR data which was adapted from an usual flux to process seismic data. The changes were introduced to take into account important differences between GPR and Reflection Seismic methods, in particular: poor coupling between source and ground, mixed phase of the wavelet, low signal-to-noise ratio, monochannel acquisition, and high influence of wave propagation effects, notably dispersion. High frequency components of the GPR pulse suffer more pronounced effects of attenuation than low frequency components resulting in resolution losses in radargrams. In Fazenda Bel?m, there is a stronger need of an suitable flux to process GPR data because both the presence of a very high level of aerial events and the complexity of the imaged subsurface karst structures. The key point of the processing flux was an improvement in the correction of the attenuation effects on the GPR pulse based on their influence on the amplitude and phase spectra of GPR signals. In low and moderate losses dielectric media the propagated signal suffers significant changes only in its amplitude spectrum; that is, the phase spectrum of the propagated signal remains practically unaltered for the usual travel time ranges. Based on this fact, it is shown using real data that the judicious application of the well known tools of time gain and spectral balancing can efficiently correct the attenuation effects. The proposed approach can be applied in heterogeneous media and it does not require the precise knowledge of the attenuation parameters of the media. As an additional benefit, the judicious application of spectral balancing promotes a partial deconvolution of the data without changing its phase. In other words, the spectral balancing acts in a similar way to a zero phase deconvolution. In GPR data the resolution increase obtained with spectral balancing is greater than those obtained with spike and predictive deconvolutions. The evolution of the Janda?ra karst in Potiguar Basin is associated to at least three events of subaerial exposition of the carbonatic plataform during the Turonian, Santonian, and Campanian. In Fazenda Bel?m region, during the mid Miocene, the Janda?ra karst was covered by continental siliciclastic sediments. These sediments partially filled the void space associated to the dissolution structures and fractures. Therefore, the development of the karst in this region was attenuated in comparison to other places in Potiguar Basin where this karst is exposed. In Fazenda Bel?m, the generation of sinkholes and terrain collapses are controlled mainly by: (i) the presence of an unconsolidated sedimentary cap which is thick enough to cover completely the karst but with sediment volume lower than the available space associated to the dissolution structures in the karst; (ii) the existence of important structural of SW-NE and NW-SE alignments which promote a localized increase in the hydraulic connectivity allowing the channeling of underground water, thus facilitating the carbonatic dissolution; and (iii) the existence of a hydraulic barrier to the groundwater flow, associated to the A?u-4 Unity. The terrain collapse mechanisms in Fazenda Bel?m occur according to the following temporal evolution. The meteoric water infiltrates through the unconsolidated sedimentary cap and promotes its remobilization to the void space associated with the dissolution structures in Janda?ra Formation. This remobilization is initiated at the base of the sedimentary cap where the flow increases its abrasion due to a change from laminar to turbulent flow regime when the underground water flow reaches the open karst structures. The remobilized sediments progressively fill from bottom to top the void karst space. So, the void space is continuously migrated upwards ultimately reaching the surface and causing the sudden observed terrain collapses. This phenomenon is particularly active during the raining season, when the water table that normally is located in the karst may be temporarily located in the unconsolidated sedimentary cap / Esta tese apresenta resultados da pesquisa realizada no campo de petr?leo de Fazenda Bel?m-CE (Bacia Potiguar), com o objetivo de entender os mecanismos de gera??o de colapsos de terreno associados ? exist?ncia de um substrato carbon?tico intensamente fraturado e karstificado da Forma??o Janda?ra. A principal ferramenta utilizada foi o imageamento do karst soterrado com GPR (Ground Penetrating Radar). Dois eixos tem?ticos de pesquisa foram desenvolvidos: um eixo de natureza geof?sica, que consistiu no desenvolvimento de metodologias de processamento de dados de GPR, e um eixo de natureza geol?gica, que consistiu do estudo do karst Janda?ra e dos fatores condicionantes da sua evolu??o. Este segundo eixo foi fortemente apoiado no estudo de estruturas k?rsticas aflorantes e na interpreta??o de radargramas do karst soterrado. Um fluxo de processamento adequado para tratar dados de GPR ? proposto a partir da adapta??o de um fluxo usual de processamento s?smico. As principais modifica??es introduzidas est?o associadas com diferen?as fundamentais existentes entre GPR e S?smica, notadamente: pior condi??o de acoplamento entre fonte e solo, fase da wavelet (que ? mista, no GPR), grande n?vel de ru?do (inclusive a?reo), aquisi??o monocanal e maior import?ncia dos efeitos de propaga??o (principalmente dispers?o) na onda eletromagn?tica. A necessidade de um processamento adequado foi ainda mais premente em Fazenda Bel?m devido ? forte presen?a de ru?do a?reo, por se tratar de uma ?rea industrial, e grande complexidade das fei??es k?rsticas soterradas. A etapa chave do fluxo de processamento ? a corre??o dos efeitos de propaga??o. Em meios diel?tricos de perda baixa a moderada, verificou-se que a propaga??o do pulso de GPR impacta fortemente o seu espectro de amplitude, mas provoca muito pouca altera??o no seu espectro de fase. P?de-se assim corrigir os efeitos da propaga??o com uma aplica??o judiciosa de ganhos e balanceamento espectral. Os ganhos foram utilizados para recuperar a perda de amplitude e o balanceamento espectral, para recuperar as componentes da faixa superior de freq??ncia, que s?o mais fortemente afetadas pelos efeitos da propaga??o. Apesar da n?o estacionaridade do sinal do GPR, o balanceamento espectral promove um aumento de resolu??o, o que qualifica esta t?cnica como um bom substituto dos algoritmos de deconvolu??o, garantindo repetitividade e independ?ncia do meio geol?gico. A karstifica??o da plataforma carbon?tica Janda?ra est? associada a, pelo menos, tr?s eventos de exposi??o sub-a?rea relacionadas ?s discord?ncias do Turoniano, Santoniano e Campaniano. Em Fazenda Bel?m, a partir do Mioceno M?dio, o karst Janda?ra foi soterrado por sedimentos silicicl?sticos continentais. Este soterramento preencheu parte das cavidades de dissolu??o e fraturas e, assim, o desenvolvimento do processo de karstifica??o foi bastante atenuado, em compara??o com outros locais da Bacia Potiguar, onde o karst Janda?ra est? exposto. Nas condi??es vigentes em Fazenda Bel?m, identificou-se que os principais fatores condicionantes do surgimento das dolinas e do colapso de terreno s?o: (i) exist?ncia de uma cobertura inconsolidada espessa o suficiente para encobrir o calc?rio, por?m delgada o suficiente para que o seu volume possa ser acomodado nos espa?os vazios dessas estruturas; (ii) ocorr?ncia da interse??o de lineamentos estruturais SW-NE e NW-SE, que promovem um aumento localizado da condutividade hidr?ulica e condicionam a canaliza??o do fluxo hidr?ulico subterr?neo, facilitando a dissolu??o dos carbonatos; e (iii) exist?ncia de uma barreira hidr?ulica vertical, associada ? Unidade A?u-4, que condiciona a circula??o da ?gua subterr?nea a ser predominantemente lateral. Os colapsos de terreno em Fazenda Bel?m seguem o seguinte processo de evolu??o temporal. O fluxo de ?gua se infiltra atrav?s da cobertura sedimentar inconsolidada e promove sua mobiliza??o para o espa?o vazio das estruturas de dissolu??o na Forma??o Janda?ra. Este efeito ? iniciado na base da cobertura sedimentar, onde o fluxo aumenta o seu poder de abras?o, devido ? mudan?a brusca do regime laminar para o regime turbulento, ao entrar no karst. O material remobilizado vai preenchendo, as cavidades intra-acamamento e geram espa?o, de forma remontante, na cobertura sedimentar acima situada, que vai se afinando at? o ponto de colapso, quando ent?o ocorrem as dolinas. Este fen?meno ? especialmente ativo durante a esta??o chuvosa, quando o n?vel est?tico da ?gua, que normalmente est? situado dentro do calc?rio, pode estar temporariamente localizado dentro da cobertura sedimentar

Die zu bearbeitende Aufgabe ist darauf ausgerichtet, das zur Prognose und Deutung von Erdfällen wichtige Grundlagenwissen zu erweitern und mit Hilfe der neu gewonnenen Erkenntnisse einige wichtige konkrete Probleme der Erdfallentstehung zu diskutieren. Dabei stützen sich die Untersuchungen auf die regionale Verkarstungs- und geologische Situation in der Mansfelder Mulde. Die Untersuchungsergebnisse werden erweiternd diskutiert (Verkarstung im Sangerhäuser Revier, Effektivität geophysikalischer Überwachungen, Möglichkeiten und Grenzen der Erdfallprognose und -deutung).

English, Afrikaans and Zulu summaries / While there is increasing interest in the effect of landscape on ancient imagination, less attention has been paid to the impact of restless karst hydrology on ancient beliefs. By identifying shared themes, this study compares and contrasts the way Hittites and Aegean people in the Late Bronze and Early Iron Ages reshaped peripheral karst landscapes into physical and imagined transitional zones. Karst geology underpins much of the Aegean and Anatolian landscape, allowing subterranean zones to be visible and accessible above ground via caves, springs, sinking streams, sinkholes and other unusual natural formations. In both cultures, certain dynamic landscapes were considered to be sacred porous points where deities, daemons, heroes and mortals could transit between cosmic realms. Evidence suggests that Hittites and Aegean people interpreted dramatic karst landscapes as liminal thresholds and spaces situated between the world of humans and the world of deities. Part One investigates physical zones of transition via the karst ecosystems of rural sanctuaries. Part Two considers the creative interpretation in myth and iconography of karst phenomena into metaphysical zones of transition. The examples reveal the way in which Hittites and Aegean people built their concept of the sacred on the extraordinary characteristics of karst geology. Numinous karst landscapes provided validity and a familiar reference point for the creation of imagined worlds where mortal and divine could connect. / Vandag is daar toenemende belangstelling in die effek van die landskap op die verbeelding van die mensdom in die oudheid - maar minder aandag word bestee aan die impak van die rustelose karst landskap op die mens se gelowigheid in die oudheid. Deur die identifisering van sekere gemene temas, vergelyk hierdie verhandeling die manier waarop die Hetiete en die Egeïese volkere in die Laat Brons- en vroeë Ystertydperke die omliggende karstlandskap herskep het in fisiese en denkbeeldige oorgangszones. Die Egeïese en Anatoliese landskap bestaan grotendeels uit karst geologie, met tot gevolg dat ondergrondse zones bo die grond sigbaar en toeganklik is in die vorm van grotte, bronne, sinkgate en ander uitsonderlike natuurlike formasies. In beide bogenoemde kulture is sekere landskapstonele beskou as heilige en poreuse punte waar gode, demone, helde en sterwelinge tussen die kosmiese zones kon beweeg. Die getuienis van die tyd suggereer dat die Hetiete en die Egeïese volkere die dramatiese karst landskappe as grense of drempels tussen hulle wêreld en dié van die gode beskou het. Deel Een ondersoek die fisiese oorgangszones deur te kyk na die karst ecostelsels waarin plattelandse heiligdomme hulle bevind het. Deel Twee beskou die kreatiewe gebruik van karst verskynsels as voorstellings van metafisiese oorgangszones in die gekrewe bronne en ikonografie. Die geselekteerde voorbeelde dui aan die manier waarop die Hetiete en Egeïese volke hulle konsepte van heiligdom gebaseer het op die buitengewone verskynsels van karst geologie. Numineuse karst landskappe het hulle idees gestaaf en ‘n bekende verwysingspunt uitgemaak waar die menslike en die goddelike met mekaar in kontak kon kom. / Ngenkathi intshisekelo ekhulayo yethonya lokwakheka komhlaba emcabangweni wasendulo, kunakwe kancane umthelela we-karst hydrology engenazinkolelo ezinkolelweni zasendulo. Ngokukhomba izingqikithi okwabelwana ngazo, lo mqondo uqhathanisa futhi uqhathanise indlela amaHeti nabantu base-Aegean kweLate Bronze kanye ne-Early Iron Ages abuye abuye abumbe kabusha imigwaqo ye-karst yomngcele ibe yizingxenye zesikhashana zomzimba nezicatshangwe. I-Karst geology isekela kakhulu indawo yezwe i-Aegean ne-Anatolian evumela ukuthi izindawo ezingaphansi komhlaba zibonakale futhi zifinyeleleke ngaphezu komhlaba ngemigede, iziphethu, imifudlana ecwilayo, imigodi yokushona nokunye ukwakheka okungokwemvelo okungajwayelekile. Kuwo womabili amasiko izindawo ezithile eziguqukayo zazithathwa njengezindawo ezingcwele zokungena lapho onkulunkulu, amademoni, amaqhawe nabantu abafayo bengadlula phakathi kwezindawo zomhlaba. Ubufakazi bukhombisa ukuthi amaHeti nabantu base-Aegean bahumusha imidwebo emangazayo yekarst njengemikhawulo yemikhawulo nezikhala eziphakathi komhlaba wabantu nezwe lonkulunkulu. Ingxenye yokuqala iphenya izindawo eziguqukayo zomzimba ngokusebenzisa imvelo ye-karst yezindawo ezingcwele zasemakhaya. Ingxenye Yesibili ibheka ukutolikwa kokudala kunganekwane nakwizithonjana zezinto ze-karst kube izingxenye eziguqukayo zenguquko. Izibonelo ziveza indlela abantu abangamaHeti nabantu base- Aegean abawakha ngayo umqondo wabo ongcwele ngezimpawu ezingavamile ze-karst geology. Amathafa amahle we-karst ahlinzeka ngokusebenza kanye nephuzu elijwayelekile lesethenjwa lokwakhiwa kwamazwe acatshangelwe lapho abantu abafayo nabaphezulu bangaxhuma khona. / Biblical and Ancient Studies / M. A. (Ancient Near Eastern Studies)